The cervical spine is a miracle in design and structure as it moves in various planes. It must support the head, and it must move the eyes and the ears for various sensory orientations.

Mechanically, the head teeters on the atlanto-occipital joints, shaped like cupped palms tipped slightly medially. Because the line of gravity falls anterior to these articulations, a force must be constantly provided in the upright posture by the posterior neck muscles to hold the head erect. Added to this gravitational stress is the action of the anterior muscles of the neck, essentially the masticatory, suprahyoid, and infrahyoid groups, which as a chain join the anterior cranium to the shoulder girdle.

Flexion, extension, rotation, lateral flexion, and circumduction are the basic movements of the cervical region. Movements of the head on the neck are generally confined to the occiput-atlas-axis complex and can be described separately from movements of the neck on the trunk. The prime movers and accessories involved in neck motion are listed in Table 7.1.

Joint Motion   Prime Movers                Accessories          
  Flexion      Sternocleidomastoid         Scalenes
               Longus colli                Hyoid muscles
               Longus capitis
               Rectus capitis anterior
               Rectus capitis lateralis

  Extension    Trapezius, upper            Transversospinalis group
               Splenius capitis            Levator scapulae
               Splenius cervicis
               Semispinalis capitis
               Semispinalis cervicis
               Erector spinae capitis
               Erector spinae cervicis

  Rotation     Sternocleidomastoid         Scalenes
               Trapezius, upper            Transversospinalis group
               Spenius capitis
               Spenius cervicis

  Lateral      Scalenes                    Transversospinalis group
  Flexion      Levator scapulae            Rectus capitis lateralis

Cervical motions are usually tested with the patient seated unless the patient is unable to hold his head erect. Passive motion should never be attempted if spinal fracture, dislocation, advanced arteriosclerosis, or severe instability is suspected.


Evaluating Gross Muscle Strength of the Neck

Muscle strength is recorded as from 5 to 0 or in a percentage and compared bilaterally whenever possible. Grading has been previously described. The major muscles of the neck, their primary function, and their innervation are listed in Table 7.2.

  Muscle                     Major Function       Spinal Segment
  Erector spinae, upper      Extension, rotation      C1–T1
  Longus colli               Flexion                  C2–C6
  Longus capitis             Flexion                  C1–C3
  Rectus capitis anterior    Flexion                  C1–C2
  Rectus capitis lateral     Flexion                  C1–C2
  Scalenes                   Flexion, rotation        C4–C8
  Semispinalis capitis       Extension, rotation      C1–T1
  Semispinalis cervicis      Extension, rotation      C1–T1
  Splenius capitis           Extension, rotation      C1–C8
  Splenius cervicis          Extension, rotation      C1–C8
  Sternocleidomastoid        Flexion, rotation        C2, XI
  Trapezius, upper           Extension, rotation      C3–C4

Blows to the head or neck may result in unconsciousness, but most blows do not. Rather, the effect is a "subconcussive" or "punch drunk" effect for a few moments. This state may be the effect of a severe blow to the head or the cumulative effects of many blows. It is assumed that the reader is well acquainted with the proper emergency procedures involved in head and neck trauma.

The anterior and lateral aspects of the neck contain a wide variety of vital structures that have no bony protection. Partial protection is provided by the cervical muscles, the mandible, and the shoulder girdle. After spinal injury, a careful neurologic evaluation must be conducted. Note any signs of impaired consciousness, inequality of pupils, or nystagmus. Do outstretched arms drift unilaterally when the eyes are closed? Standard coordination tests such as finger-to-nose, heel-to-toe, heel-to-knee, and for Romberg's sign should be conducted, along with superficial and tendon reflex tests. For reference, the segmental functions of the cervical nerves are listed in Table 7.3.

Cervical spine injuries can be classified as being:

(1) mild (eg, contusions, strains);

(2) moderate (eg, subluxations, sprains, occult fractures, nerve contusions, neurapraxias);

(3) severe (eg, axonotmesis, dislocation, stable fracture without neurologic deficit); and

(4) dangerous (eg, unstable fracturedislocation, spinal cord or nerve root injury).

Segment   Function

  CERVICAL PLEXUS (C1–C4)

  C1      Motor to head and neck extensors, infrahyoid, rectus capitis
          anterior and lateral, and longus capitis.

  C2      Sensory to lateral occiput and submandibular area; motor, 
          same as C1 plus longus colli.
 
  C3      Sensory to lateral occiput and lateral neck, overlapping
          C2 area; motor to head and neck extensors, infrahyoid,
          longus capitus, longus colli, levator scapulae, scaleni,
          and trapezius.

  C4      Sensory to lower lateral neck and medial shoulder area;
          motor to head and neck extensors, longus coli, levator
          scapulae, scaleni, trapezius, and diaphragm.

  BRACHIAL PLEXUS (C5–T1):

  C5      Sensory to clavicle level and lateral arm (axillary
          nerve); motor to  deltoid, biceps; biceps tendon reflex.
          Primary root in shoulder abduction, exits between
          C4–C5 discs.

  C6      Sensory to lateral forearm, thumb, index and half of
          2nd finger (sensory branches of musculocutaneous nerve);
          motor to biceps, wrist extensors; brachioradialis tendon
          reflex. Primary root in wrist extension, exits between
          C5–C6 discs.

  C7      Sensory to second finger; motor to wrist flexors, 
          finger extensors, triceps; triceps tendon reflex.
          Primary root in finger extension, exits between
          C6–C7 discs.

  C8      Sensory to medial forearm (medial antebrachial nerve),
          ring and little fingers (ulnar nerve); motor to finger
          flexors, interossei; no reflex applicable. Primary root
          in finger flexion, exits between C7–T1 discs.

  T1      Sensory to medial arm (medial brachial cutaneous nerve);
          motor to interossei; no reflex applicable. Primary root
          in finger abduction, exits between T1–T2 discs.

Injury Incidence

Due to its great mobility and relatively small structures, the cervical spine is the most frequent site of severe spinal nerve injury and subluxations. A wide variety of cervical contusions, Grade 1–3 strains and sprains, subluxations, disc syndromes, dislocations, and fractures will be seen as the result of trauma. The peak incidence of cervical injury occurs in the 3rd decade, with the vast majority of the accidents occurring in males. Body build does not appear to be a major factor. High-speed activities have the highest injury rate.

Considerable cervical spine injury can be attributed to the small, curved vertebral bodies, the wide range of movement in many planes, and the more laterally placed intervertebral articulations which require the nerve roots to leave the spinal canal in an anterolateral direction. There is greater space within the cervical canal than below, but this space is occupied by cord enlargement.

The axis and C6 are the most vulnerable to injury according to accident statistics. The atlas is the least involved of all cervical vertebrae. In terms of segmental structure, the vertebral arch (50%), vertebral body (30%), and IVD (30%) are most commonly involved in severe cervical trauma. While the anterior ligaments are only involved in 2% of injuries, the posterior ligaments are involved in 16% of injuries.


Basic Posttraumatic Roentgenographic Considerations of the Neck

A well-founded appreciation of normal variations, epiphyseal architecture, development defects, and congenital anomalies is a distinct aid in evaluating injuries of the cervical area. After the age of 8 years, the neck, with few exceptions, attains an adult form in which growth plates present few diagnostic problems.

On the standard lateral and A–P views, the anterior and posterior soft tissues deserve careful inspection. Signs of widened retrotracheal space, widened retropharyngeal space, displacement of the prevertebral fat stripe, laryngeal dislocation, or tracheal displacement should be sought. Abnormal vertebral alignment may be exhibited by a loss of the normal lordotic curve or even an acute kyphotic hyperangulation, vertebral body displacement, abnormal dens position, widened interspinous space, or rotation of the vertebral bodies. Abnormal joints may portray unusual IVD-space symmetry or widening of an apophyseal joint space. It is easy to miss lower cervical fractures inasmuch as they are often obscured on lateral views by the subject's shoulders if proper precautions are not taken.


Classic Effects of Severe Cervical Trauma

      COMPRESSION FORCES

Excessive compression forces on the neck commonly lead to facet jamming and fixation, isolated or multiple fractures of the atlantal ring, or vertical, oblique, or bursting fractures of the lower cervical bodies.

      HYPERFLEXION FORCES

Excessive anterior bending forces may produce hyperflexion sprain of the posterior ligaments, compressive wedging of the anterior anulus and vertebral body, anterior subluxation, anterior bilateral or unilateral dislocation with locked facets, and spinous process avulsion. Abnormal widening of a spinous interspace on a lateral roentgenograph should arouse suspicion of ruptured posterior ligaments.

      HYPEREXTENSION FORCES

The effects of posterior bending moments may include hyperflexion sprain of the anterior ligaments, wedging of the posterior anulus and vertebral body, posterior subluxation, horizontal fracture of the anterior arch of the atlas, fracture of the anteroinferior margin of a vertebral body, compression of the posterior arch and associated structures, posterior bilateral or unilateral dislocation, spinous process fracture, and traumatic spondylolisthesis.

      HYPERROTARY FORCES

Excessive segmental rotation about the longitudinal axis produces anterior or posterior ligament torsion overstress, rotary subluxation, spiral loosening of the nucleus pulposus, and unilateral or bilateral atlas-axis dislocation. The traumatic moments involved invariably include shear forces.

      SHEAR FORCES

Excessive shearing forces create disruption of the anterior or posterior ligaments, end-plate displacement, anterior or posterior subluxation or dislocation, anterior or posterior fracture displacement of the dens, and anterior compressive fracture of the anterior ring of the atlas or a vertebral body.

      LATERAL HYPERFLEXION FORCES

The effects of excessive lateral bending include transverse process fracture, uncinate process failure, lateral dislocation-fracture of the odontoid process, lateral wedging of the anulus and vertebral body, and brachial plexus trauma.


Soft-Tissue Injuries of the Posterolateral Neck

      CERVICAL CONTUSIONS

Contusions in the neck are similar to those of other areas. They often occur in the cervical muscles or spinous processes. Painful bruising and tender swelling will be found without difficulty, especially if the neck is flexed. They present little biomechanic significance unless severe scarring occurs.

      DIRECT NERVE TRAUMA

Nerve trauma occurs from contusion, crushing, or laceration.

Neurapraxia.   Recovery of nerve contusion usually occurs within 6 weeks. Nerve contusion may be the result of either a single blow or through persistent compression. Fractures and blunt trauma are often associated with nerve contusion and crush. Peripheral nerve contusions exhibit early symptoms when produced by falls or blows. Late symptoms arise from pressure by callus, scars, or supports. Mild cases produce pain, tingling, and numbness, with some degree of paresthesia. Moderate cases manifest these same symptoms with some degree of motor and/or sensory paralysis and atrophy4.

Axonotmesis.   After nerve crush, recovery rate is about an inch per month between the site of trauma and the next innervated muscle. If innervation is delayed from this schedule or if the distance is more than a few inches, surgical exploration should be considered.

Neurotmesis.   Laceration from sharp or penetrating wounds is less frequently seen than tears from a fractured bone's fragments. Surgery is usually required. Stretching injury typically features several sites of laceration along the nerve and is usually limited to the brachial plexus.

      GENERAL ASPECTS OF STRAINS AND SPRAINS

Anterior injuries are more common to the head and chest as they project further anteriorly, but a blunt blow from the front to the head or chest may result in an indirect extension or flexion injury of the cervical spine. In any spinal injury, rarely is the trauma the product of a single force. For example, while extension, flexion, and lateral flexion injuries are often described separately in this chapter, rotational, compressive, tensile, and shearing forces are invariably part of the picture.

Incidence.   Strains (Grades 1–3) or indirect muscle injuries are common, frequently involving the erectors. Flexion and extension cervical sprains are also common (Grades 1–3) and usually involve the anterior or posterior longitudinal ligaments, but the capsular ligaments may be involved. In the neck especially, strain and sprain may co-exist. Severity varies considerably from mild to dangerous. The C1 and C2 nerves are especially vulnerable because they do not enjoy the protection of an IVF.

Typical Signs and Symptoms.   Cervical sprain and disc rupture are often associated with severe pain and muscle spasm and are more common in adults because of the reduced elasticity of supporting tissues. Pain is often referred when the brachial plexus is involved. Cervical stiffness, muscle spasm, spinous process tenderness, and restricted motion are common. When pain is present, it is often poorly localized and referred to the occiput, shoulder, between the scapulae, arm or forearm (lower cervical lesion), and may be accompanied by paresthesiae. Radicular symptoms are rarely evident unless a herniation is present. Spasm of the sternocleidomastoideus and trapezius may be due to strain or irritation of the sensory fibers of the spinal accessory nerve as they exit with the C2–C4 spinal nerves.

Case Management.   Diagnosis and treatment are similar to that of any muscle strain-sprain, but concern must be given to induced subluxations during the initial strain. Palpation will reveal tenderness and spasm of specific muscles. In acute scalene strain, both tenderness and swelling will usually be found. When the longissimus capitis or the trapezius are strained, they stand out like stiff bands.

Prognosis.   Many cervical strains heal spontaneously but may leave a degree of fibrous thickening or trigger points within the injured muscle tissue. Residual joint restriction following acute care is more common in traditional medical care than under mobilizing chiropractic management.

      EXTENSION STRAIN/SPRAIN

The head may be flexed forward so that the chin strikes the sternum or thrown sidewards so that the ear strikes the shoulder and the neck can still be within the normal range of motion. It is most rare, however, that the occiput strikes the back and does not exceed normal cervical extension.

Mechanisms.   Other than those in automobile accidents, the forces in whiplash are usually administered from below upward; eg, an uppercut blow to the chin or a blow to the forehead while running forward. This is in contrast to the compressive type of hyperextension or hyperflexion injury where the force is usually from above downward. Thus, knowing the direction of force, even if the magnitude is unknown, is important in analyzing the effects. A facial injury usually suggests an accompanying extension injury of the cervical spine as the head is forced backward.

Kinematics.   In whiplash resulting from a mild automobile collision, the cervical trauma is due to indirect trauma from acceleration-deceleration forces. If the head does not strike anything, the injury is produced solely by inertia forces (Fig. 7.8). The body is moving as a whole at the same speed as the automobile. If the automobile is struck from the rear, the unrestrained head is whipped backward because the head is not restrained by the seat, and then rebound forward. If the automobile is struck from the front or hits a relatively immovable object, the head is thrown forward and then rebound backward. Thus, the inertia force displaces the head in the direction opposite to the automobile's acceleration. The first movement is that of translation which produces a shearing force at the base of the neck because the bending moment is greatest at that point.

The rebound is caused by several factors. In a front-end collision, for example, there is an initial flexion elongation of the cervical spine after impact that is followed by a rebound extension. The rebound is produced by the rapid deceleration of the automobile, the impact from the seat, and the stretch reflex produced within the stretched neck and upper dorsal muscles. This reflex can be quite severe, and because it occurs when the neck is at its full range of movement, the pull generates considerable compression as well as extension.

Effects.   When the head is violently thrown backwards (eg, whiplash), the damage may vary from minor to severe tearing of the anterior and posterior longitudinal ligaments. This flattens the cervical curve in about 80% of cases, and a degree of facet injury must exist even if not evident on film. Stretching to the point of hematoma may occur in the sternocleidomastoideus, longus capitis, longus cervicis, and scalene muscles (Fig. 7.9). Severe cord damage can occur that is usually attributed to momentary pressure by the dura, ligamentum flavum, and laminae posteriorly, even without roentgenologic evidence. Even without any cord deficit, severe damage to the nerve roots may occur as the facets jam together and close upon the IVF, especially if fracture occurs. Incidence is highest at the C4–C6 area. Severe stretching of the vertebral arteries and sympathetic trunk to some degree is inevitable.

Cailliet points out that it is difficult to visualize a sprain causing rupture of the ligaments of a joint without causing some derangement of the opposing joint surfaces, which by definition is an orthopedic subluxation. If a whiplash injury is considered a severe sprain, an orthopedic subluxation injury must be assumed to have occurred even if it has been spontaneously reduced. Such subluxations may occur during the initial movement and/or the rebound movement, and it is not unusual to have manifestations of a flexion sprain superimposed upon manifestations of an extension sprain. In the typical whiplash injury, whether it be from hyperextension or hyperflexion or both, the effects of traumatic elongation and compression are compounded by underlying fixations, arteriosclerosis, spondylosis, ankylosing spondylitis, etc.

Case Management.   Treatment of mild or moderate injuries not exhibiting severe neurologic trauma requires reduction of subluxation, physiotherapeutic remedial aid, a custom-fitted supporting collar for several weeks depending upon the clinical symptoms and signs, and graduated therapeutic exercises beginning with isometric contractions. Continuous traction, which reduces the cervical lordosis, may be helpful in extension injuries after the acute stage, but it would usually be contraindicated where the cervical curve has reversed (eg, flexion strain).

      FLEXION STRAIN/SPRAIN

Slight anterior subluxation is usually not serious, but neurologic symptoms may appear locally or extend down the arm.

Mechanisms.   An occipital injury usually suggests an accompanying flexion injury of the anterior cervical spine and posterior soft tissues as the skull is forced forward (Fig. 7.10). Flexion injury may also be a part of whiplash, superimposed upon an extension injury.

Effects.   The posterior paraspinal tissues are overstretched, the facets are sprung open, and the process of bleeding, edema, fibrosis, and adhesions is initiated. Fractures of end-plates may be difficult to assess early. Disc degeneration and posttraumatic osteoarthritis may follow, which leads to spondylosis.

Case Management.   Management is similar to that of extension injuries except that the period of necessary immobilization is often shorter (6–8 weeks).

      LATERAL FLEXION STRAIN/SPRAIN

Traumatic brachial plexus traction syndromes will be discussed later in this chapter. These usually occur when the neck is not only severely flexed sideward but also flexed forward and down so that the head is anterior to the shoulder.

      TRIGGER POINTS

The cervical and suprascapular areas of the trapezius, usually a few inches lateral to C7, frequently refer pain and deep tenderness to the lateral neck (especially the submastoid area), temple area, and angle of the jaw (Fig. 7.11). The sternal division of the sternocleidomastoideus refers pain chiefly to the eyebrow, cheek, tongue, chin, pharynx, throat, and sternum. The clavicular division refers pain mainly to the forehead (bilaterally), back of and/or deep within the ear, and rarely to the teeth. Other common trigger points involved in "stiff neck" are in the levator scapulae, the splenius cervicus lateral to the C4–C6 spinous processes, and the splenius capitis over the C1–C2 laminae (Fig. 7.12). These points are often not found unless the cervical muscles are relaxed during palpation.

Therapy.   Peripheral inhibitory afferent impulses can be generated to partially close the pre-synaptic gate by acupressure, acupuncture, or transcutaneous nerve stimulation. Most authorities feel deep sustained manual pressure on trigger points is the best method, but a few others prefer almost brutal short-duration pressure (1–2 seconds). Deep pressure is contraindicated in any patient receiving anti-inflammatory drugs (eg, cortisone) as subcutaneous hemorrhage may result.

      MYOFASCIAL TRIGGER POINTS IN THE NECK AND BACK

Visceral or somatic trigger-point irritation can produce a degree of spasm of the paravertebral muscles ipsilaterally in 2–3 segments on the same side as the entering afferent. However, if the irritation is severe, this effect will spread up, down, and contralateral (eg, as in renal colic). In this regard, Stoddard reminds us that the sharp "textbook" demarcation made between the somatic and autonomic nervous systems is erroneous.

      Common Sites

Although one or more trigger points may occur in any muscle, they usually form in clusters and certain muscles and muscle groups (eg, the antigravity muscles) appear to be more liable than others. See Table 7.4

     UPPER BODY

     Location                     Primary Reference Zone or Symptoms
     Infraspinatus                Posterior and lateral aspects of the shoulder.

     Intercostal muscles          Thoracodynia, especially during inspiration.

     Levator scapulae             Posterior neck, scalp, around the ear.

     Pectoralis major             Anteromedial shoulder, arm.

     Pectoralis minor             Muscle origin or insertion.

     Quadratus lumborum           Anterior abdominal wall, 12th rib, iliac crest.

     Rectus abdominus             Anterior abdominal wall.

     Semispinalis capitis         Headache, facial pain, dizziness.

     Splenius cervicis            Headache, facial pain, dizziness.

     Sternocleidomastoideus       Headache, dizziness, neck pain, ipsilateral ptosis,
                                  lacrimation, conjunctival reddening, earache,
                                  facial and forehead pain.

     Trapezius                    Lower neck and upper thoracic pain, headache.
     
LOWER BODY

     Location                     Primary Reference Zone or Symptoms
     Anterior tibialis            Anterior leg and posterior ankle.

     Gastrocnemius/soleus         Posterior leg, from popliteal space to heel. These
                                  trigger points may be involved in intermittent
                                  claudication.

     Gluteus medius               Quadratus lumborum, tensor fasciae latae, gluteus
                                  maximus and minimus, sacroiliac joints, hip,
                                  groin, posterior thigh and calf, cervical exten-
                                  sors, upper thoracic muscles.

     Tensor fasciae latae         Lateral aspect of the thigh, from ilium to the knee.

Reference patterns vary considerably according to the severity and chronicity of the trigger point phenomenon involved.

      ADJUNCTIVE THERAPIES

The reduction of spasm is often necessary prior to structural correction and to maintain a corrected position after adjustment.

Passive Stretch.   Mild passive stretch is an excellent method of reducing spasm in the long muscles. Heavy passive stretch, however, destroys the beneficial reflexes. One technique, for example, is to place the patient prone on an adjusting table in which the headpiece has been slightly lowered. The patient's head is turned toward the side of the spastic muscle. With head weight alone serving as the stretching tensile force, the spasm should relax within 2–3 minutes. Thumb pressure, placed on a trigger area, is then directed toward the muscle's attachment and held for a few moments until relaxation is complete.

Therapeutic Heat or Cold.   Heat is also helpful, but cold and vapocoolant sprays have shown to be more effective in acute cases.

Therapeutic Exercise.   Mild isotonic exercises are useful for improving circulation and inducing the stretch reflex, especially in the cervical extensors. These exercises should be done supine to reduce exteroceptive influences on the central nervous system. In chronic cases, relaxation training with biofeedback is helpful.

Traction.   The effects of cervical traction are often dramatic but sometimes short lived if a herniated disc is involved. Extreme care must be taken in posttraumatic cases to eliminate the possibility of instability prior to traction. For example, the use of traction following traumatic spondylolisthesis in which the anterior longitudinal ligament has been separated can produce severe displacement with catastrophic effects (Fig. 7.13).

In any vertebral, occipital, or pelvic subluxation, physiotherapy, traction, muscle relaxants, gross manipulations, muscle stretching, injections, or other methods will not offer much relief by themselves unless the fixated articulation is correctly adjusted so that intrinsic function can be normalized.

For study, it is best to divide the cervical spine into upper and lower regions because of its anatomic design and functional arrangement. The upper spine is composed of the occipital condyles, the atlas, and the axis. It is different morphologically and functionally from the lower cervical spine that is made up of vertebrae C3–C7. The axis is thus a transitional vertebra in that its superior aspect is part of the upper complex and its inferior aspect is part of the lower complex.


Regional Structural Characteristics

The spinal canal of the upper cervical region is relatively large to accommodate the cervical enlargement of the cord. The pedicles, apophyseal joints, uncinate processes, and transverse processes have characteristics peculiar and specific to the cervical spine.

      THE ATLAS

In several anatomic respects, the atlas can be considered a sesamoid between the occiput and axis that serves as a biomechanical washer or bearing between the occipital condyles and the axis (Fig. 7.14). The atlas is an elongated bony ring with right and left lateral masses, an anterior arch, a posterior arch, and bilateral transverse processes that extend from each lateral mass. The absent body of the atlas is represented by its anterior arch and the dens of the axis. The inner aspect of the anterior arch contains a facet for the dens. An IVD does not exist between the occiput and the atlas, nor does the atlas exhibit IVF's or a distinct spinous process.

The Lateral Masses and Articular Processes.   The lateral masses are oval in shape with an oblique anteromedial articulation. They must support the weight of the head, which comprises about 7% of body weight. The articular surfaces on the superior side of the lateral masses are biconcave to allow for the seating and movement of the biconvex occipital condyles and are relatively large to dissipate the weight of the head. The inferior articulating facets of the atlas have an inferomedial articulation with anteroposterior convexity to fit the articulation of the superior facets of the axis. These inferior facets of the atlas lie directly underneath the superior facets, unlike those of subjacent apophyseal joints whose inferior facets lie posterior to the superior facets.

The Posterior Arch.   The posterior arch of the atlas thickens posteriorly to where it forms the posterior tubercle (Fig. 7.15). The posterior arch is grooved to offer some bony protection for the vertebral artery which runs just behind the lateral mass. This groove is a frequent fracture site.

The Transverse Processes.   Only the lumbar vertebrae have transverse processes that extend further from the midline than the atlas. This great width increases the leverage of the muscles that insert at the transverse processes. Unlike other cervical vertebrae, the transverse processes of the atlas are not grooved to allow egress of a nerve root. The transverse processes of the atlas, as other cervical vertebrae, contain a conduit (foramen transversarium) for the vertebral artery.

      THE AXIS

The inferior facets of the atlas fit the superior facets of the axis like epaulets on sloping shoulders (Fig. 7.16). The plane is about 110° to the vertical. To allow maximum rotation of the upper cervical complex without stress to the contents of the vertebral canal, the instantaneous axis of rotation is placed close to the spinal cord (ie, near the atlanto-odontoid articulation).

The Anterior Arch.   The C1–C2 joint is an unusual joint in that the inner anterior arch of C1 has a small facet that is in contact with the odontoid process of C2, separated only by a small synovial cavity. A small synovial bursa also separates the posterior aspect of the odontoid from the cruciate ligament (Fig. 7.17). The osseous and ligament complex of this area allows great rotation and some flexion and extension. The anterior arch of C1 normally remains 1 mm from the odontoid in flexion and extension. If there is widening of this space greater than 3 mm in the adult or 4 mm in the child, damage to the transverse ligament of the atlas can be suspected.

Rotational Restriction.   Rotation of C2 on C3 is limited by a mechanical blocking mechanism that protects the vertebral artery from excessive torsion. The anterior tip of the superior articular process of C3 impinges on the lateral margin of the foramen transversarium of C2. This same blocking mechanism is also found in the subjacent cervical vertebrae (Fig. 7.18).

      THE OCCIPITOCERVICAL LIGAMENTS

The cross-shaped cruciate ligament completely secures the odontoid process. Its main portion is the triangular bilateral transverse ligament, which passes posteriorly on the dens and connects to the lateral masses of the atlas, transversing in front of the spinal cord. Its main function is to restrict anterior translation of the atlas. There are also two vertical bands. One rides from the dens up to the basiocciput, and the other extends from the dens posteriorly down to the body of the axis. Because these ligaments are often tough, the odontoid will usually fracture prior to ligament failure. In addition, accessory atlantoaxial ligaments extend superiorly and laterally from the base of the inferior vertical cruciate and join the base of the dens with the inferomedial aspect of the lateral mass of C1.

Anterior to the upper arm of the cruciate lie the apical and alar ligaments. The thin, elastic apical ligament connects the tip of the dens to the anterior margin of the foramen magnum, and the stronger lateral alar ligaments connect the medial aspect of the occipital condyles obliquely with the superolateral aspect of the odontoid (Fig. 7.19). These three guy-wire ligaments, collectively called the dentate ligaments of the dens, tend to limit rotation and lateral bending, but their capabilities are quite limited.

The atlantoepistrophic ligament runs between the anterior body of the axis and the inferior aspect of the anterior ring of the atlas, and the atlantooccipital ligament connects the superior aspect of the anterior ring of the atlas and the occipital tubercle.

The posterior longitudinal ligament terminates upward as the strong, broad, fan-shaped membrana tectoria which extends superiorly from the base of the odontoid, over the posterior dens, then obliquely angles forward to blend with the dura and the clivus of the basiocciput periosteum at the anterior aspect of the foramen magnum. Its most posterior aspect joins the occiput to the posterior ring of the atlas, and it serves to check excessive A–P motion. Its deep lateral part connects the posterior body of C2 with the anterolateral ring of the atlas.

The broad, dense, anterior longitudinal ligament blends posteriorly with the anterior atlanto-occipital membrane which extends superiorly from the upper body of the axis to connect the anterior tubercle of the atlas with the margin of the foramen magnum. It blends laterally with the facet capsules.

The ligamentum flavum terminates superiorly as the posterior atlantoaxial membrane that joins the posterior arch of the axis to the posterior ring of the atlas. It then arches over the vertebral artery above the atlas and attaches to the foramen magnum as the atlanto-occipital membrane to join the atlas with the occiput (Fig. 7.20).

Short, thin capsular ligaments surround the atlanto-occipital diarthrotic articulations; and short, thick, loose capsular ligaments surround the C1–C2 diarthrosis. Their fibers lie perpendicular to the facet planes, and they are remarkably lax when the articulations are in a position of rest. The capsules are reinforced laterally by the atlanto-occipital fibers extending from the jugular process of the occiput to the lateral masses of the atlas and the transverse processes of the axis. The capsular and lateral ligaments are normally loose enough in the A–P plane to allow nodding, but taut enough laterally so that the occiput and atlas move as a unit during moderate rotation and lateral flexion of the neck (Fig. 7.21).

The triangular nuchal ligament band runs in the midline from the posterior border of the occiput to the posterior tubercle of the atlas and the C2–C7 spinous processes, dividing the posterior aspect of the neck into right and left halves. It is not unusual to find evidence on a lateral roentgenograph of nuchial ossification, indicating an old spinous process fracture.


Kinematics of the Upper Cervical Spine

An understanding of the basic kinematics of the cervical spine is vital to accurate clinical diagnosis and therapeutic applications. All movements in the cervical spine are relatively free because of the saddle-like joints. The cervical spine is most flexible in flexion and rotation. The latter occurs most freely in the upper cervical area and is progressively restricted downward.

Note: The specific range of cervical motion differs quite widely among so many authorities that any range offered here should be considered hypothetical depending on individual planes of articulation, other variances in structural design (eg, congenital, aging degeneration, posttraumatic), and soft-tissue integrity. This wide variance in opinion is also true for the centers of motion described.

      BIOMECHANIC UPPER CERVICAL INSTABILITY

Moderately strong soft-tissue connections exist within the occiput-atlas-axis complex. Osseous, muscle, tendon, ligament, and lymph node abnormalities tend to restrict motion, while tissue tears and lax ligaments without associated muscle spasm all too much motion.

Stability is provided the C1–C2 joint by paravertebral ligaments and muscle attachments. When weakening of these supports occurs (eg, rheumatoid arthritis, trauma, postural stress), a dangerous state of instability can arise. Each infant presents a considerable degree of cervical instability because of the relatively large head weight superimposed on the small underdeveloped spine.

      FLEXION AND EXTENSION

A great deal of cervical motion is concentrated in specific spinal areas. About half of flexion and extension occurs at the atlanto-occipital joints, with the other half distributed among the remaining cervical joints. Inasmuch as the nucleus of the disc is nearer the anterior of a complete cervical vertebra, A–P motion is more discernible at the spinous process than at the anterior aspect of the vertebral body.

Flexion Range.   Without any neck participation, the head can be moved 10° in flexion between the occiput and atlas, according to Cailliet (Fig. 7.22). During strict upper neck flexion, the condyles roll backward and slide slightly posterior on the atlas while the atlas rolls anteriorly and somewhat superiorly, taking the odontoid with it so that the dens slightly approaches the clivus of the basiocciput. As the atlas slides anteriorly in relation to the condyles, the posterior arch of the atlas and occiput separate only slightly, but this is exaggerated if movement is virtually isolated at the atlanto-occipital joint (eg, ankylosing spondylitis). Also during flexion, the inferior lateral masses of the atlas roll upward posteriorly and slide backward on the superior facets of the axis for about 5°. Opening of the superior aspect of the atlanto-odontoid space is not appreciably restricted by the delicate cruciate ligament. Movement is restricted mainly by the apophyseal capsules, the ligamentum flavum, the interspinous ligament, the posterior nuchal muscles, and impact of the chin against the sternum.

Extension Range.   The skull can be extended on the atlas for about 15° without any participation by other cervical vertebrae. During normal extension of the neck, the condyles slide anteriorly on the atlas; the atlas rolls upward so that its posterior arch approximates the occiput. Slight opening of the inferior aspect of the atlanto-odontoid space occurs, but it is limited by the tectorial membrane. Similarly, the posterior arches of the atlas and axis also approximate. The range of extension of C1 on C2 is usually given as 10°. During forced extension, the posterior arch of the atlas is caught as in a vise between the occiput and axis.

Active Motion.   Regional active cervical flexion and extension motions are tested by having the patient raise and lower the chin as far as possible without moving the shoulders. Note smoothness of motion and degree of limitation bilaterally.

Passive Motion.   Passive cervical flexion and extension are examined by placing the hands on the sides of the patient's skull and rolling the skull anteroinferior so that the chin approximates the sternum and posterosuperior so that the nose is perpendicular to the ceiling.

      ROTATION

Approximately half of rotational movement takes place at the atlantoaxial joints about the odontoid process, with the remaining half distributed fairly evenly among the other cervical joints. During rotation, the odontoid represents a peg encased within a fairly enclosed ring or a stake surrounded by a horseshoe.

Range.   During rotation, the occipital condyles and the atlas initially move as one unit on the axis (Fig. 7.23). Approaching the end of the range of motion, the condyles can rotate several degrees (8°–10°) upon the atlas in the direction of movement. Only a few authorities contest this fact. C1 rotation occurs about the dens of C2 which serves as a pivot. As mentioned, 50% of total neck rotation occurs between C1 and C2 (capable of 80°–100° rotation) before any rotation is noted from C2 to C7 or at the atlantal-occipital joint. After about 30° of atlas rotation on the dens, the body of the axis begins to rotate, followed by progressively diminishing rotation in the remaining cervical segments. Because the atlantal-occipital and atlantoaxial apophyseal articulations are not horizontal, rotation must be accompanied by a degree of coupled tilting.

Active Rotation.   Regional active rotary motion is tested by having the patient move his nose as far as possible to the left and right without moving his shoulders. Note smoothness of motion and degree of limitation bilaterally.

Passive Rotation.   Passive rotation is examined by placing the hands on the patient's skull and turning the head first to one side and then to the other so that the chin is in line with the shoulder.

If a complete fixation occurs between C1 and C2, the remaining cervical segments tend to become hypermobile in compensation. Thus, gross inspection of neck rotation (or other motions) should never be used to evaluate the function of individual segments.

      LATERAL FLEXION

Cervical lateral flexion is essentially performed by the unilateral contraction of the neck flexors and extensors with motion occurring in the coronal plane. Such flexion is accompanied by rotational torsion below C2, distributed fairly equally in the normal cervical joints. That is, when the cervical spine as a whole bends laterally, it also tends to rotate anteriorly on the side of the concavity so that the vertebral bodies arc further laterally than the spinous processes.

Range.   Normally, about a 45° tilt can be observed between the skull and the shoulder. About 5° of this occurs at the atlanto-occipital joint (Fig. 7.24), following the arc of the condyles on the superior facets of the atlas; and 6° occurs at the atlantoaxial joint, following the arc of the inferior facets of the atlas on the superior facets of the axis. As the occiput and atlas shift laterally as one unit towards the concavity during lateral bending, the space between the dens and lateral mass of the atlas widens on the concave side. At the same time, the occipital condyles translate slightly laterally on the superior facets of the atlas toward the convexity and the atlas slips slightly toward the side of concavity. These movements are quite slight unless there is a degree of instability involved. If the atlanto-occipital capsular ligaments are weakened, the condyle on the side of lateral bending may strike the tip of the odontoid. The body of the axis tends to rotate towards the concavity while its spinous process shifts toward the convexity due to the coupling mechanism.

Active Lateral Flexion.   Regional active side bending is tested by having the patient attempt to touch each ear on the respective shoulder without moving the shoulders.

Passive Lateral Flexion.   Passive side bending is tested by placing your hands on the patient's skull and bending the head sideward toward the patient's fixed shoulder on each side.

      OCCIPITOATLANTAL MOVEMENT

The oblique cup-and-saucer atlanto-occipital joints are designed essentially for a limited range of A–P nodding movement. Translatory movements are slight; most action is a rolling movement. The long axes of the joints are obliquely set, but a slight curve in the coronal plane allows a few degrees of lateral tilt.

Flexion/Extension.   The prime mover of atlanto-occipital flexion is the rectus capitis anterior, aided by the longus capitis. The range is limited essentially by the elasticity of the posterior ligaments and by the tip of the dens meeting the bursa below the anterior rim of the foramen magnum. Extension is powered by the rectus capitis posterior group. Extension and lateral tilt of the upper cervical region is restricted by tension of the tectorial membrane and the posterior arch of the atlas becoming trapped between the occiput and the axis.

Lateral Flexion.   Lateral bending is produced by the rectus capitis lateralis, with assistance by the semispinalis, splenius capitis, sternomastoideus, and trapezius. The range is limited essentially by the alar ligaments. In mild coronal lateral flexion and transverse rotation of the head and neck, the occiput and atlas move as a unit because of the planes of the articular facets. Close observation will show that the occiput specifically abducts on the atlas without rotation about a vertical axis. Thus, the atlas is caught between trying to follow the motion of the occiput or the axis. This stress, according to Gillet, forces a slight amount of rotation of the occiput on the atlas even though the design of the condyles is not conducive to such rotation.

      ATLANTOAXIAL MOVEMENT

The loose articular capsules of the C1–C2 joint probably allow the greatest degree of inherent instability present in the cervical spine.

Flexion/Extension.   In addition to the rolling motion of the atlas on the occiput, the atlas is capable of some tilting where the anterior ring of the atlas moves upward on the odontoid and the posterior arch rides downward, or vice versa (Fig. 7.25). During severe flexion, there could be considerable separation of the anterior arch of the atlas from the odontoid, but it is checked by the weak transverse arms of the cruciate and by tension of the stronger tectorial membrane. Extension is more readily resisted when the anterior arch meets the odontoid and the interarticular tissues compress.

Rotation.   During normal movement, the occiput and atlas move as one about the odontoid process of the axis. Keep in mind that the odontoid of the axis is usually quite firmly attached to the occiput via the ligament complex. These ligaments (especially the alar ligaments, transverse cruciate, and the apophyseal capsules of the axis) tend to restrict axial rotation to 45° as compared to a 90° range by the atlas. Although the inferior facets of the atlas and the superior facets of the axis may both be concave, their articular cartilages offer a biconvex design. Atlantoaxial rotation is powered by the obliquus capitis and rectus capitis posterior major, with assistance offered by the ipsilateral splenius capitis and the contralateral sternocleidomastoid. During maximum atlantoaxial rotation in a supple spine, there is considerable kinking or stretching of the contralateral vertebral artery.

Lateral Flexion.   When lateral flexion is fairly restricted to the upper cervical area, the articulating facet spaces open on the side of convexity and compress on the side of concavity. However, when lateral flexion is fairly generalized throughout the cervical region, the lateral masses of the atlas sideslip towards the side of concavity so that the space between the lateral mass and the odontoid increases on the side of the concavity. Naturally, this is limited by the size of the bony crescent about the dens unless the cruciate is torn.

Disturbances in this area usually arise from muscular spasm of one or more of the six muscle bundles that have attachments on the occiput, atlas, or axis. Unequal tension and ultimate fibrotic changes within the paravertebral structures can readily influence the delicate nerve fibers and vascular flow. The vertebral artery is frequently involved by compression of the overlying muscles in the suboccipital triangle. In fact, West points out that the vertebral artery has been completely occluded by turning the head backward and to the opposite side during postmortem studies. Even without a degree of arteriosclerosis, the vertebral artery can be considered a quite firm tube in the adult that responds poorly to twisting and pressure.

      BACKGROUND

Neurologic disturbances may result from muscular and fibrotic changes along the cranial nerve pathways which exit from the skull and pass intimately between and under suboccipital fasciculi. Five of the cranial nerves are thus vulnerable: the facial, glossopharyngeal, vagus, spinal accessory, and hypoglossal. In addition, circulatory impairment of major and minor nerves of the neck may alter the function of those cranial nerves that do not exit from the skull proper, such as the olfactory, optic, oculomotor, trochlear, trigeminal, abducens, and auditory, but which are contained within the cranium and remote from vertebral subluxation encroachment effects. We should not overlook the fact that it is essentially muscle which produces and maintains the subluxation. Attention must be paid to the reasons why the subluxation has been produced and is maintained.

A careful study of most clinical subluxations will reveal that they are infrequently "unusual" positions. Commonly, they are normal positions in a state of fixation. In the neutral position, for example, an inferior atlas subluxation-fixation exhibits the posterior arch of the atlas approximating the spinous process of the axis –the normal position of the atlas during extension. The same is true of superior, posterior, and lateral listings: all are normal positions if found in flexion, rotation, or lateral bending, but abnormal if found in other positions.

In a discussion of spinal motion of any region or segment complex, it should be constantly kept in mind that minor pathologic changes and individual variances from the "norm" considerably alter the biodynamics involved. Neither static position on roentgenography and/or dynamic palpation alone can be used as the basis to determine the need or the results of adjustive therapy. Static palpation is often grossly in error because of the many anomalies in asymmetry found in the typical spine. The whole clinical picture must be utilized.

      COMMON OCCIPITAL SUBLUXATIONS

Inasmuch as all freely movable articulations are subject to subluxation, the atlanto-occipital diarthrosis is no exception. The stress at this point is unusual when one considers that the total weight of the cranium is supported by the ring of the atlas, about 1/20th the circumference of the skull, and a variety of spinal muscles, subject to spasm and hypertonicity, have their attachments on the occiput.

Being near the end of a kinematic chain, the atlanto-occipital joints are subject to numerable degrees of subluxation in flexion, extension, rotation, and laterality. Rotary subluxation is not uncommon, especially if the atlantal cups are shallow. Excessive rotation is allowed by the lax check ligaments and capsules. Head weight, the angle of force, the planes of articulation, and the integrity of the para-articular tissues determine the stability present.

Right/Left Condyle Inferior or Superior.   A unilateral suboccipital muscle spasm causes the affected condyle to be pulled deep into the articulating concavity of the atlantal lateral mass on one side (sunken condyle). This may not be attended by a degree of rotation. Inspection from the back shows a low, medially inclined mastoid process on the side of involvement (Fig. 7.26). Palpation discloses the mastoid riding close to the transverse process of the atlas, tension and tenderness in the groove between the mastoid and the lower jaw, and fullness in the groove between the occiput and the posterior ring of the atlas on the side of involvement. A right or left condyle superior may be considered the converse aspect of a right or left condyle inferior. That is, as one condyle is pulled inferior and anterior, the other condyle presents a superior and posterior picture, or vice versa. There are certain situations, however, that indicate a unilateral abnormality without converse adaptation. This latter condition usually follows a blow to the vertex downward when the head is somewhat laterally flexed and the condyle on the side of the concavity is jammed into the lateral mass of the atlas (eg, spearing tackle).

Right/Left Condyle Inferior with Associated Anterior Rotation.   All atlanto-occipital movements tend to be associated with a degree of rotation because the occipital condyles and the articulating surfaces of the lateral masses of the atlas approximate each other more at the anterior than the posterior. Thus, most sunken condyles will be associated with a relative amount of rotation. On the side of involvement, inspection from the back reveals a medial head tilt. Palpation reveals approximation of the mastoid and transverse process of the atlas and approximation of the inferior nuchal ridge and the posterior arch of the atlas on the involved side. These points are widened on the opposite side. A right or left superior condyle with associated posterior rotation is often considered the contralateral aspect of a right or left inferior condyle attended by an anterior rotation. Illi feels it is always attended by a degree of arthritis and determines the primary subluxation roentgenographically by the side showing the greatest degree of degenerative articular alteration.

Right/Left Condyle Inferior with Associated Posterior Rotation.   This type of subluxation or its contralateral representation is less common than that associated with anterior rotation. It usually results from vigorous twisting trauma such as in athletic contact activities. On the side of involvement:

(1) inspection from the back shows the head held in a stiff inferior position with some posterior deviation; and

(2) palpation discloses a mastoid that is inferior and posterior in relation to the transverse process of the atlas, and the inferior nuchal ridge approximating the posterior arch of the atlas.

Suboccipital Jamming.   This common subluxation, usually of a trigeminal (ophthalmic division) reflex nature, is often seen in people under severe visual or mental stress. Irritative impulses cause contraction of suboccipital muscles that pull the occiput upon the posterior arch of the atlas, creating a painful bilateral condylar jamming (Fig. 7.27). A compressive vertex blow is a rare cause. Palpation reveals suboccipital spasm, tenderness, nodular swellings, and a closing of the inferior nuchal ridge on the posterior arch of the atlas. Although the condition is usually bilateral, one side may be affected more than the other.

      COMMON ATLAS SUBLUXATIONS

Right or Left Lateral Atlas.   An atlantal sideslip between the atlas and axis articulations is usually attended by a degree of superiority and anteriority on the side of laterality because of the inclination of the articulating surfaces. Only in cases of severe twisting trauma will this not be the case. Ipsilaterally, palpation will reveal the transverse process of the atlas to be more lateral and slightly superior and anterior than its counterpart.

Bilateral Superior or Inferior Atlas.   In this type of subluxation, the atlas tilts up or down bilaterally in its transverse plane without an attending side-slip. Deep palpation may reveal the posterior arch of the atlas either approximating the occiput with a gap between the posterior tubercle of the atlas and the spinous of the axis or approximating the spinous process of the axis with a gap between the atlas' posterior tubercle and the occiput (Fig. 7.28).

Right or Left Fixed Anterior Rotation of the Atlas.   These subluxations are often associated with vagal syndromes because the anteriorly rotated transverse of the atlas may easily cause pressure on the vagus nerve. In such a rotatory state, the counterpart of an atlas listed right anterior would be left posterior. On the side of involvement, inspection from the back reveals suboccipital fullness. Bilateral palpation of the posterior ring of the atlas reveals a prominence on the side of posteriority, with the transverse process of the atlas being closer to the mastoid and its counterpart closer to the mandible.

A clinical test, suggested by Goodheart, is to have the patient lying supine, then passively rotating the head right and left. If an anterior atlas subluxation exists on the left, the atlas has already turned to the right so that the patient's head will turn much further to the right. But when it is turned from right to left, the atlas cannot come out of its fixed anterior position on the left, thus motion is relatively restricted. This test is a valid indication only in the absence of muscular spasm or some other type of motion barrier restricting rotation (eg, lower cervical unilateral fixation).

      COMMON AXIS SUBLUXATIONS

With the possible exception of L5, no other vertebra is subluxated more frequently than the transitional C2. The C2–C3 apophyseal joints are the most mobile and least stable of any in the vertebral column with the exception of the C1–C2 joints. The most common symptom is a unilateral suboccipital neuralgia on the side of rotational posteriority. On this side, palpation discloses a tender prominence over the articulating process and a deviation of the spinous process away from the midline (Fig. 7.29). Posterior axial subluxations are sometimes misdiagnosed as anterior atlantal subluxations.

Rotary subluxations of the axis are common structural causes of cervical migraine. This cervical neuralgia is invariably unilateral, beginning in the upper neck and extending over the skull into the temporal and possibly the orbital areas. The greater occipital nerve (C2) is affected (Fig. 7.30).

Rotary subluxations of one or more of the upper three vertebrae (particularly the axis) may cause pressure upon the superior cervical ganglion. The autonomic syndrome produced may incorporate excessive facial and forehead perspiration, dry mouth and nasal mucous membranes, dryness and tightness of the throat, dilated pupils tending toward exophthalmos, pseudomigrainous attacks due to unilateral angioneurotic edema, facial vasomotor disturbances with possible angioneurotic swelling, and moderate tachycardia with functional arrythmias.

      FRACTURES AND DISLOCATIONS OF THE ATLAS

Atlanto-occipital dislocations, often bilateral, are usually quickly incompatible with life. Any severe orthopedic subluxation in the upper cervical area can lead to quadriplegia or death, often with little warning and few symptoms to differentiate it initially from a mild strain. Thus, it is always better to be extra cautious (and be accused of being overly concerned in mild injuries) to insure against a possible disaster. Signs and symptoms vary from subtle to severe pain and gross motor involvement. Tenderness may be acute over the posterior atlas, aggravated by mild rotation and extension.

These severe disorders are presented here for two reasons. First, an acute patient may enter the office after suffering an accident. Second, an untreated fracture or spontaneously reduced dislocation may have healed without adequate professional care and reflect symptoms many months or years later.

Classes.   The atlas may be fractured at its posterior arch, ring, or anterior arch. There are six common types of severe injury, all of which are serious. Keep in mind that nontraumatic dislocations of the upper cervical complex are more common than traumatic dislocations (eg, congenital anomalies, arthritis, infection), and their possibility should never be overlooked.

1. Atlanto-occipital dislocation.   This usually, but not always, anterior displacement of the occiput on the atlas occurs from a severe horizontal force from behind that shears the skull across the atlas, rupturing the articular capsules, and damaging the medulla. This rare occurrence can often be accurately evaluated by computing Powers ratio on a lateral roentgenograph (Fig. 7.31).
   
   

2. Atlas dislocation with fractured dens.   The atlas may displace anteriorly on the axis or the occiput posteriorly on the atlas and fracture the odontoid process if the ligaments hold. The force may be hyperextensive or hyperflexive. The patient may survive if extreme care is taken in transportation to the hospital. If the transverse ligament is avulsed from the atlas, a small fragment of bone may lie between the odontoid and the cord. If the odontoid is displaced posteriorly, the situation is usually fatal because of injury to the cord. Posttraumatic spontaneous fusion of C1 to the occiput is always a potential complication if the patient survives.
   
   

3. Fractured posterior arch of the atlas.   This usually occurs from a severe vertical compression force during extension where the lateral masses are fixed between the condyles and the pillars of the axis and the posterior ring fractures and displaces outward. A base fracture of the odontoid is often associated. If a fracture line is not evident on lateral roentgenography (differentiated from congenital clefts), headache, suboccipital pain, stiffness, acute suboccipital jamming, and subtle signs of basilar insufficiency from compression of the vertebral artery should still stimulate suspicions.
   
   Of all atlantoid fractures, most literature states that those of the posterior arch are the most common yet easily overlooked as the displacement is usually mild. The common site is at the narrowest portion just posterior to each lateral mass, usually at the groove for the vertebral artery. Retropharygeal swelling is usually absent, and oblique views are often necessary for demonstration.
   
   

4. Jefferson fracture.   A more severe vertical compression blow may split the atlas and burst the lateral masses outward, disrupting both the anterior and posterior rings into several fragments (Fig. 7.32). Ring fractures are frequently produced by blows on top of the head where vertical forces are dispersed laterally. Keep in mind that if a severe axial force is produced through the skull downward, the inclined condyles of the occiput serve as a mechanical wedge upon the atlas. This is usually evident in an open-mouth x-ray view. Overhang of the atlantal lateral masses and widening of the paraodontoid space will be associated. Severity depends upon fragment displacement relative to the cord and other vital tissues. That is, if the ligaments do not retain these fragments, death from cord damage will be likely.
   
   Another point to consider is that the cervical spine has a natural lordosis which normally dissipates axial forces. However, as the neck moves from the extended to the flexed position, a position is reached where the vertebrae are fairly aligned vertically. A rapid compression overload in this position is most likely to result in an exploding-type fracture.
   
   Most authorities state that fractures of the anterior arch are rare, minimally displaced, usually comminuted, and frequently require tomography to be detected. However, Iversen/Clawson feel that fractures to the anterior arch are quite common and found either in the midline or just lateral to the midline.
   
   

5. Atlas-axis displacement.   In C1–C2 A–P dislocations, C1 most often displaces anteriorly relative to C2. If a force comes from the back, undoubtedly the muscles will be unprepared and the force will meet minimum resistance. Yet, anterior dislocation is rare, and posterior displacement is even more infrequently seen. Forward dislocation widens the predental space and alters a roentgenographic line connecting the cortices of the anterior parts of the spinous processes from C1 to C7, unless the process of C2 is fused or congenitally short. If this is suspected, careful flexion-extension views or a C1–C2 tomogram is recommended. The mechanism of injury is usually hyperflexion or hyperextension; and even in moderate cases, signs of trauma to the occipital nerve should be evident. In rare instances where there are sufficient traction forces to rupture the anterior longitudinal ligament, the anterior ring of the atlas may be lifted up and over the dens so that an intact odontoid is seen anterior to the anterior ring.
   
   

6. Orthopedic rotary subluxation of the atlas on the axis.   Forced rotation of the upper neck may produce a locked rotary displacement of a lateral mass of the atlas on the subjacent superior facet of the axis. This requires atlantal rotation in excess of 45° on the axis. A neurologic deficit is not commonly involved. The patient will appear with his head rotated to one side and cocked away from the side of rotation ("cock robin" position). Care must be taken to differentiate this sign which is also so common in acute torticollis.

      FRACTURES AND DISLOCATIONS OF THE AXIS

Odontoid fractures are often produced by severe forces directed to the head, and the direction of force usually determines the direction of displacement. Suboccipital tenderness may be present. A severe extension force may fracture the odontoid at its base, with possible odontoid posterior displacement. The danger of cord pressure is great.

Open-mouth and careful flexion-extension standard roentgenographic views or tomography may be necessary for accurate determination. The atlantal-dens interval should not exceed 2–3 mm in adults even during cervical flexion. The interval is slightly more (eg, as much as 4–5 mm during flexion) in children under the age of 8 years.

Types.   The classic order of Anderson/D'Alonzo is applicable:

Type I:   Avulsion of the upper part of the odontoid. This is rare.

Type II: Fracture through the base of the odontoid at or below the level of the superior articular facets of the axis. This is the most common type of axial fracture, and the cruciate ligaments may remain intact. Occasionally the odontoid will not be displaced but be slightly tipped as a result of a toggle effect shown on flexion-extension films. This type fracture is usually quite unstable and leads to nonunion.

Care must be taken not to confuse odontoid nonunion with os odontoideum. In os odontoideum, the process is about 50% smaller than normal, round, and separated from the hypoplastic odontoid by a wide gap. The remnant hypoplastic odontoid appears as a hill forming upward from the slope of the superior articular facets. The fracture line in nonunion is narrow and at or below the level of the superior articular facets, and the process is normal in size and shape.

Type III: Fracture of the body of the axis.   Displacement may not occur. A small bone chip separated from the anteroinferior rim of the axis at the point of rupture of the anterior longitudinal ligament (Fig. 7.33) may be a clue to hyperextension –associated with retropharyngeal soft-tissue swelling and/or dislocation of the prevertebral fat stripe. About 36% of axial fractures occur through the cancellous bone of the body of the axis, are stable, and heal without difficulty. End-plate fracture and displacement are invariably associated.

Hangman's Fracture.   This traumatic spondylolisthetic injury by distraction and extension causes fracture of the C2 when the chin is fixed and the forehead is struck. The classic damage is a bilateral fracture through the lateral posterior arch and into the intervertebral notch. The posterior elements of the axis dislocate in relation to C3, while the anterior elements dislocate in relation to the atlas and skull. Survival is not common, but when it occurs without overt spinal cord involvement, only minor complaints such as local pain, stiffness, and tenderness over the spinous process may be expressed.

Vertical Dislocation.   This is usually a secondary effect of a pathologic process where the odontoid enters the foramen magnum (eg, rheumatoid arthritis, spinal tuberculosis, osteogenesis imperfecta, or Paget's disease). The severity of neurologic involvement varies considerably from case to case regardless of roentgenographic findings.

Regional Structural Characteristics

Nature has made many structural adaptations in the cervical region because of the small structures, the required range of motion, and the enlarged cord in this region as compared to other spinal regions (Fig. 7.34). The laminae are slender and overlap, and this shingling increases with age. The osseous elevations on the posterolateral aspect that form the uncovertebral pseudojoints tend to protect the spinal canal from lateral IVD herniation, but hypertrophy of these joints added to IVD degeneration can readily lead to IVF encroachment.

The IVD's are broader anteriorly than posteriorly to accommodate the cervical lordosis. Authorities differ as to the typical location of the nucleus pulposus in the cervical region. Kapandji places it centrally. Cailliet places it slightly posterior (further anterior than a lumbar nucleus), and Jeffreys says it is distinctly posterior from the midline.

      THE INTERVERTEBRAL FORAMEN

The boundaries of the cervical IVF's are designed for motion rather than stability as compared with the dorsal and lumbar regions (Fig. 7.35). The greatest degree of functional IVF diameter narrowing occurs ipsilaterally in lateral bending with simultaneous extension.

      THE FACET JOINTS

The articular processes incline medially in the coronal plane and obliquely in the sagittal plane so that they are at about a 45° angle to the vertical.

Their bilateral articular surface area, which shares a good part of head weight with the vertebral body, is about 67% of that of the vertebral body.

The short, thick, dense capsular ligaments bind the articulating processes together, enclosing the articular cartilage and synovial tissue. Their fibers are firmly bound to the periosteum of the superior and inferior processes and arranged at a 90° angle to the plane of the facet. This allows maximum laxity when the facets are in a position of rest. They normally allow no more than 2–3 mm of movement from the neutral position per segment, and possibly provide more cervical stability than any other ligament. Capsulitis from overstretch in acute subluxation is common. The posterior joint capsules enjoy an abundance of nociceptors and mechanoreceptors, far more than any other area of the spine.

Within the capsule, small tongues of meniscus-like tissue flaps project from the articular surfaces into the synovial space. They are infrequently nipped" in severe jarring at an unguarded moment during the end of extension, rotation, or lateral bending, establishing a site of apophyseal bursitis (Fig. 7.36).

      THE LOWER CERVICAL LIGAMENTS

The five lower, relatively similar, cervical vertebrae possess eight intervertebral ligamentous tissues, four posterior and four anterior. The anterior ligaments are the anterior longitudinal ligament, the anulus fibrosus, the posterior longitudinal ligament, and the intertransverse ligament. The posterior ligaments are the ligamentum flavum, the capsular ligaments, and the interspinous and supraspinous ligaments.

The anterior longitudinal ligament rides close to the anterior vertebral bodies and blends with the anulus as it crosses the IVD space. It is quite thin, translucent, and thickest and widest over the anterior anulus. It tends to limit extension, as does the anulus.

The posterior longitudinal ligament is firmly attached to the IVD but separated from the vertebral bodies (except the lips) by the retrocorporeal nutrient vessels. By not following the concavity of the vertebral bodies, the posterior longitudinal ligament offers a smooth anterior wall for the spinal cord. However, thickening or ossification of this ligament can encroach upon the vertebral canal. It is much thicker than its anterior counterpart, but as its counterpart, it is widest as the disc level. It tends to limit flexion, as does the anulus.

The thin, fibrous, intertransverse ligament runs longitudinally between adjacent transverse processes, just anterior to the vertebral artery, joining the anteroinferior aspect of the transverse process above to the anterosuperior lip of the transverse process below. It serves to limit contralateral lateral bending and rotation.

The strong, thick, elastic ligamentum flavum connects the lamina of adjacent vertebrae, riding essentially within the vertebral canal. Its usually great elasticity prevents buckling that would impinge upon the contents of the spinal canal (Fig. 7.37).

The interspinous ligament and the supraspinous ligament are poorly developed in the upper cervical region. In the lower levels, the supraspinous ligament is continuous with the ligamentum nuchae posteriorly and continuous with the interspinalis ligaments anteriorly. The supraspinous ligaments overlap and obliquely cross the midline, attaching themselves to the cervical spinous processes. The interspinous and supraspinous ligaments tend to check flexion, rotation, and anterior displacement during flexion.

The inelastic ligamentum nuchae extends in the posterior midline from the vertebra prominens to the occiput, blending with the posterior edge of the interspinous ligament (Fig. 7.38). It is poorly developed in humans as compared to most other mammals, yet it serves as a cervical strap that is a mechanism of defense against flexion injuries of the intrinsic muscles and structural displacement. When it degenerates (eg, old age), the head droops forward from the trunk and the cervical curve straightens.


Kinematics of the Lower Cervical Spine

The IVD's contain an exceptional amount of elastin, which allows the IVD's to conform to the many possible planes of movement. Excessive flexion is limited by the ligamentous and muscular restraints on the separating posterior arches, and overextension is limited by bony apposition. Other factors include the resistance of the anular fibers to translation, the stiffness property of the anulus relative to its vertical height, and the physical barrier produced by the uncinate processes that are fully developed in late adolescence.

      BIOMECHANIC LOWER CERVICAL INSTABILITY

Subtle instability is rarely obvious in the ambulatory patient. The most important stabilizing agents in the mid and lower cervical spine are the anulus fibrosus, the anterior and posterior ligaments, and the muscles, especially, which serve as important contributing stabilizers. Upon dynamic palpation, any segmental motion exceeding 3 mm should arouse suspicions of lack of ligament restraint.

Segmental Angulation.   Angulation of one vertebral segment on a lateral roentgenograph in excess of 11° greater than an adjacent vertebra that is not chronically compressed is also indicative of instability and pathologic displacement (Fig. 7.39). While conservative traction may reduce the associated displacement, it is doubtful that a normal resting position can be guaranteed without surgical fusion in severe cases.

Neurologic Deficit.   There is a rough correlation between the degree of structural damage present and the extent of the neurologic deficit. This is more true in the lower cervical area than that of the upper region where severe damage may appear without overt neurologic signs. In either case, however, it is doubtful that such a deficit would exhibit without an unstable situation existing. It is not unusual for a patient to exhibit a neurologic deficit without static displacement; ie, the vertebral segment has rebounded back into a normal position of rest.

      FACET ACTION

In the middle and lower cervical areas, A–P motion is a distinctly gliding translation because of the 45° facet planes and the A–P biconcave discs and vertebral bodies. During flexion and extension, the superior vertebra's inferior facets slide anterosuperior and posteroinferior on the inferior vertebra's superior facets. During full flexion, the facets may be almost if not completely separated. It is for this reason that an adjustment force is usually contraindicated in the fully flexed position. The center of motion is often described as being in the superior aspect of the body of the subjacent vertebra.

Some pivotal tilting of the superior facets, backward in extension and forward in flexion, is also normal near the end of the range of motion. The facets also tend to separate (open) on the contralateral side of rotation and lateral bending. They approximate (jam) during extension and on the ipsilateral side of rotation and lateral bending. Likewise, the foramina normally open on flexion, narrow on extension, and close on the concave side of lateral flexion. Because of the anterosuperior slant of the lower cervical facets, an inferior facet that moves downward must also slide posterior, and vice versa.

Any corrective adjustment must take into consideration the overall degree of the cervical lordosis, the planes of articulation, the facet tilting present, and the degree of facet opening, as well as any underlying pathologic process involved, and applying just enough force to overcome the resistance of the fixation.

      COUPLING PATTERNS

During lateral bending, the vertebral bodies tend to rotate toward the concavity while the spinous processes swing in a greater arc towards the convexity. Note that this is exactly opposite to the coupling action in the lumbar spine. During cervical bending to the right, for example, the right facet of the superior vertebra slides down the 45° plane toward the right and posterior and the left facet slides up the 45° incline toward the left and anterior. This coupling phenomenon is seen in circumstances in which an unusual ratio of axial rotation and lateral bending produces a subluxation or unilateral facet dislocation.

The amount of cervical rotation that is coupled with lateral flexion varies with the segmental level. At C2, there is 1° of rotation with every 1.5° of lateral flexion. This 2:3 ratio changes caudally so that the degree of coupled rotation decreases. For example, at C7, there is 1° of rotation for every 7.5° of lateral flexion, a 2:15 ratio.

      RANGE OF MOTION

All cervical vertebrae from C2 to C7 partake in flexion, extension, rotation, and lateral flexion, but some segments (eg, C5) are more active than others. In the C3–C7 area, flexion and extension occur as slight gliding translation of the upper on the lower facets, accompanied by disc distortion. The site of greatest movement in flexion is near the C4–C5 level (39°), while extension movement is fairly well diffused. This fact probably accounts for the high incidence of arthritis at the midcervical area. Rotation is greatest near the C5–C6 level (34°), slightly less above (26°–28°) and considerably less below (13°–15°). Lateral bending in greatest near the C2–C3 level (20°) and is diminished caudally (15°–17°). The arc of lateral motion is determined by the planes of the covertebral joints (Fig. 7.40).

      MOTION OF THE TRANSITIONAL CERVICOTHORACIC AREA

In the cervicothoracic area, normal movement is somewhat similar to that in the lumbosacral area insofar as the type of stress (not magnitude of load) to which both areas are subjected is similar. L5 is relatively immobile on the sacrum and C7 is relatively immobile on T1, with the major amount of movement in the cervicothoracic junction being at C6–C7 and primarily that of rotation.

      REVERSAL OF THE NORMAL CERVICAL CURVE

As opposed to the primary thoracic kyphosis which is a structural curve, the cervical and lumbar anterior curves are functional arcs produced by their wedge-shaped IVD's and they normally flatten in the nonweightbearing supine position. Likewise, they quickly adapt to changes involving the direction of force.

A pathologic straightening of the normal anterior curve of the cervical spine, as viewed in a lateral weight-bearing x-ray film, results in mechanical alteration of normal physiologic and structural integrity (Fig. 7.41). The normal vertical A–P line of gravity, as viewed laterally, falls approximately through the odontoid and touches the anterior border of T2. As the cervical spine tends to flatten in the erect position, the gravity line passes closer to the center of the cervical discs.

Incidence.   Cervical kyphosis occurs most frequently after the age of 40, and the sexes appear equally affected. The cause is often the result of trauma-producing whiplash injury, herniated disc, subluxation, dislocation, fracture, and/or ligamentous (especially posterior) injury. Torticollis, arthritis, malignancy, tuberculosis, osteomyelitis, and other pathologies may be involved.

Etiology.   While the cervical curve is the first secondary curve to develop in the infant, its maintenance in the erect posture is essentially determined by the integrity of the lumbar curve. A flattened cervical spine that is not compensatory to a flattened lumbar spine is usually the result of a local disorder such as a subluxation syndrome caused by posterior shifting of one or more disc nuclei, hypertonicity of anterior musculature, or anterior ligamentous shortening as the result of local overstress, inflammation, occupational posture, or congenital anomaly.

Symptoms and Signs.   Cervical flattening is usually the result of paraspinal spasm secondary to an underlying injury, irritation, or inflammatory process. The acute clinical picture is one of torticollis. Other manifestations include headaches (occipital, occipital-frontal, supraorbital), vertigo, tenderness elicited on lateral C4–C6 nerve roots, neuritis involving branches of the brachial plexus due to nerve-root pressure, hyperesthesia of one or more fingers, and loss or lessening of the biceps reflex on the same or contralateral side. In rare cases, the triceps reflex may be involved. One or more symptoms are frequently aggravated by an abnormal position of the head such as during reading in bed, an awkward sleeping position, or long-distance driving.

Roentgenographic Considerations.   Rehberger reports the typical radiographic findings to include loss of the normal lordotic curve by the straightened cervical spine (78% cases), anterior and posterior subluxation on flexion and extension views, narrowing of IVD spaces at C4–C6 in 46% cases, discopathy at the affected vertebral level as the injury progresses, and osteoarthritic changes which are often accompanied by foraminal spurring.

Biomechanics.   A flattened cervical spine in the erect posture resembles a normal spine during flexion. To appreciate the mechanisms involved, it is well here to review the biomechanics involved. The nucleus of the disc serves as a fulcrum during flexion and return extension. When the spine is subjected to bending loads during flexion, half of the disc on the convex side suffers tension, widens, and contracts, while the other half of the disc on the concave side suffers compression, thins, and bulges. Concurrently, the nucleus bulges on the side of tension and contracts on the side of compression, which increases tension on the adjacent anulus. This creates a self-stabilizing counteracting flexion force to the motion unit that aids a return to the resting position.

Case Management.   Specific correction of offending vertebral subluxations should be accomplished. Adjunctive care includes massage and methods to reduce muscle spasm such as ultrasound, diathermy, hydrocollator packs, reflex spinal techniques, and a rolled towel placed under the neck in the supine position to increase the cervical curve. The individual should be instructed to sleep without a pillow. Cervical muscle re-education is quite helpful.

Prognosis.   Rehberger and Barge report that the prognosis is excellent if the condition is treated early and the case is not complicated by fracture or dislocation, but guarded if the trauma is severe. In cases of minimal cervical discopathy, at least symptomatic relief can be expected. Prognosis is poor in advanced degenerative osteoarthritis.

A classification of musculoskeletal disorders of the neck is given in Table 7.6.

Priority                                  Priority
Suspect                                   Suspect
Nerve(s)       Area of Localized Pain     Nerve(s)        Area of Localized Pain
Trigeminal     Anterior head and face     T5–12           Peritoneum
C1–2, T7–12    Occiput                    T6–10           Pancreas, spleen
C2–3           Forehead                   T7–9            Ascending colon
C3, T1–5       Neck                       T8–9            Gallbladder
C3–4, T1–3     Aortic arch                T9–10           Small intestines
C3–4, T1–5     Heart                      T9–11           Transverse colon
C3–4, T1–8     Head and face              T10–11          Umbilical area, ovary,
C3–4, T3–5     Lungs                                         testicle
C3–4, T6–7     Stomach, cardiac aspect    T10–12          Crown of head, scrotum,
C3–4, T8–10    Stomach, pyloric aspect                       lower limbs
C3–4, T7–9     Liver                      T10–12, S1–3    Prostate
C4             Shoulder girdle, temple    T10–L1          Kidney, uterine body
                 area                     T11–L1          Urethra, epididymis
C5             Deltoid area               T11–L2          Bladder neck, descend-
C6             Thumb                                         ing colon
C7             First or index finger      T11–L1          Suprarenal area
C8             Fourth finger              T12–L1, S1–4    Uterine neck
T1             Fifth finger               T12–L2          Ureter
T1–4           Thorax                     L1              Groin
T2             Nipple area                L1–3, S1–4      Bladder body, rectum,
T2–4           Bronchi                                       genital organs
T2–5           Upper limbs                L3              Knee, medial aspect
T2–12          Pleura                     L5              Great toe
T4–5           Mammae bodies              S1              Fifth toe
T4–7           Thoracic aorta             S2              Thigh, posterior aspect
T5–8           Esophagus (caudal)         S2–4            Cervix

Cervical Subluxation Syndromes

Subluxations, regardless of region, are difficult to classify under normal categories of trauma because they can involve bone, joint, muscle, ligament, disc, nerve, cord, lymphatic and vascular tissues. Thus, subluxation is a finding and a syndrome and not a diagnosis.

Once a vertebra loses its ideal relationship with contiguous structures and becomes relatively fixed at some point within its normal scope of movement, it is no longer competent to fully participate in ideal coordinated spinal movement. The affected area becomes the target for unusual weight bearing and traumatic stress. In addition to attending circulatory and static changes in the involved area, there is disturbed neural activity that may be exhibited as changes in superficial and deep reflexes, tremors and spasms, hyperkinesia, pupillary changes, and excessive lacrimation.

      PERTINENT FUNCTIONAL ANATOMY OF THE CERVICAL PLEXUS

The dura mater of the spinal cord is firmly fixed to the margin of the foramen magnum and to the 2nd and 3rd cervical vertebrae. In other spinal areas, it is separated from the vertebral canal by the epidural space. Since both the C1 nerve and the vertebral artery pass through this membrane and both are beneath the superior articulation of the atlas and under the overhanging occiput, atlanto-occipital distortion may cause traction of the dura mater producing irritation of the artery and nerve unilaterally and compressional occlusion contralaterally. De Rusha feels that this helps us understand those cases of suboccipital neuralgia where a patient upon turning his head to one side increases the headache and vertigo that are relieved when the head is turned to the opposite side.

There is also a synapse between the upper cervical nerves and the trigeminal nerve, which also supplies the dura mater. This may explain why irritation of C1 results in a neuralgia not only confined to the base of the skull but is also referred to the forehead or eye via the supraorbital branch of the trigeminal. The greater occipital (C2) nerve does not tend to do this. It exits between the posterior arch of the atlas and above the lamina of the axis (Fig. 7.48), referring pain to the atlanto-occipital area (Fig. 7.30) and often to the vertex of the head.

The superficial sensory cutaneous set of the cervical plexus (C1–C4) is frequently involved in subluxations of the upper four segments (refer to Table 7.4), particularly when there are predisposing spondylitic degenerative changes. Janse describes four resultant neuralgias:

(1) lesser occipital nerve neuralgia, involving the posterior area of the occipitofrontalis muscle, mastoid process, and upper posterior aspect of the auricle;

(2) greater auricular nerve neuralgia, extending in front and behind the auricle, skin over the parotid gland, paralleling the distribution of the auriculotemporal branch of the trigeminus and easily misdiagnosed as chronic trifacial neuralgia;

(3) cervical cutaneous nerve neuralgia, involving the area of the middle third of the platysma to the midline, possibly extending from the chin to the sternum;

(4) supraclavicular nerve neuralgia, depending upon which rami are affected, the neuralgia may involve the suprasternal area, pectoral area, or deltoid area. Thus, sternoclavicular and acromioclavicular neuralgias may originate in the spinal levels of the supraclavicular nerve.

De Rusha suggests that dysphagia and dysarthria may at times be due to upper cervical involvement rather than a central nervous system situation. The C1 joins the hypoglossal cranial nerve which supplies the intrinsic muscles of the tongue. It then descends to join the descending cervical which is derived from C2 and C3. A loop of nerves, the ansi hypoglossi, which supplies muscles necessary for deglutition and speaking, is derived from C1–C3.

Irritative lesions involving the cervical articulations may in turn irritate the sympathetic nerve plexuses ascending into the head via the vertebral and carotid arteries. Some cases of visual and aural symptoms are related to upper cervical distortion where the arch of the atlas snugly hugs the occiput, thus possibly irritating the sympathetic plexus near the vertebral artery as well as partially compressing the vessel. To appreciate this, note that the visual cortical area of the occipital lobe requires an ideal blood supply dependent on the sympathetics ascending the great vessels of the neck, and this holds true for the inner ear as well. To test this syndrome, De Rusha suggests having the supine patient read some printed matter while the examiner places gentle traction on the skull, separating the atlanto-occipital articulations. A positive sign is when the patient, often to his surprise, experiences momentarily enhanced visual acuity or a reduced tinnitus.

      CERVICAL NERVE ROOT INSULTS

Disturbances of nerve function associated with subluxation syndromes basically manifest as abnormalities in sensory interpretations and/or motor activities (Fig. 7.49). These disturbances may be through one of two primary mechanisms: direct nerve or nerve root disorders, or of a reflex nature.

Sensory Changes.   When direct nerve root involvement occurs on the posterior root of a specific neuromere, it manifests as an increase or decrease in sensitivity over the dermatome. A typical example includes foraminal occlusion or irritating factors exhibited clinically as hyperesthesia, particularly on the dorsal and lateral aspects of the thumb and radial side of the hand, when involvement occurs between C5–C6. Another example is on the dorsum of the hand, the index and middle fingers, and the ventroradial side of the forearm, thumb, index and middle fingers, when involvement occurs between C6–C7. In other instances, this nerve root involvement may cause hypertonicity and the sensation of deep pain in the musculature supplied by the neuromere. For example, in C6 involvement, there is deep pain in the biceps; or in C7 involvement, there is deep pain in the triceps and supinators of the forearm. Direct pressure near the nerve root or along its distribution may be particularly painful.

Motor Changes.   Nerve root insults from subluxations may also be evident as disturbances in motor reflexes and/or muscular strength. Examples of these reflexes include the deep tendon reflexes such as seen in the reduced biceps reflex when involvement occurs between C5–C6; or the reduced triceps reflex when involvement occurs between C6–C7. These reflexes must also be compared bilaterally to judge whether hyporeflexia is unilateral. Unilateral hyperreflexia is pathognomonic of an upper motor neuron lesion. Prolonged and/or severe nerve root irritation may also cause evidence of trophic changes in the tissues supplied.

Underlying Factors.   The common subluxation picture is rarely pure. It is often superimposed upon subclinical processes in the mature patient such as vertebral instability, osteochondrophytic ridges at the uncovertebral joints, apophyseal thickening and exostosis, or canal encroachment by a buckling ligamentum flavum, spinal stenosis, posterior vertebral body spurs, disc protrusions, dura and dentate thickening, arachnoid cysts, dura and arachnoid adhesions, and ossification of the posterior longitudinal ligament.

Loss of disc space, especially in the lower cervical area, may contribute as a source of chronic irritation to an already inflamed root by altering the angulation of the IVF tunnel. The sequence of inflammation, granulation, fibrosis, adhesion formation, and nerve root stricture may follow, along with a loss in root mobility and elasticity. These degenerative changes are not as pronounced during youth.

      SUBLUXATION–INDUCED REFLEX SYNDROMES

Certain spinosomatic and spinovisceral syndromes may result from cervical subluxation. For example, if the involvement is in the area of C1–C4, the cervical portion of the sympathetic gangliated chain or the 9th–12th cranial nerves as they exit from the base of the skull and pass into their compartments within the deep cervical fascia may be involved. The syndrome may include:

(1) suboccipital or postocular migraine;

(2) greater occipital nerve extension neuralgia;

(3) mandibular, cervical, auricular, pectoral, or precordial neuralgia;

(4) paroxysmal torticollis;

(5) congestion of the upper respiratory mucosa, paranasal sinuses, or eustachian tube with hearing loss;

(6) cardiorespiratory attacks;

(7) ocular muscle malfunction;

(8) pathologic hiccups;

(9) scalenus anticus syndrome; or

(10) painful spasms in the suboccipital area.

Phillips states that if a subluxation produces a stretching of the paravertebral musculature, there will be a continuous barrage of afferent impulses in the Group Ia fibers. "These afferent impulses monosynaptically bombard the alpha motor neurons causing the paravertebral musculature to go into tetany. There is a cessation of this afferent barrage when the stretch is released. The muscle stretching also initiates afferent impulses in the Group II afferents from flower spray endings which may reinforce the spastic muscle condition." He goes on to say that trauma to facet joints, disturbed articular relationships, spasms of closely related muscles, and overlying trigger points –all the result of a subluxation– set up a barrage of flexor-reflex afferent impulses via the Group II–IV fibers that converge upon the internuncial pool in lamina 7 of the spinal cord. "This abundant supply of flexor-reflex afferent impulses excites the alpha motor neurons through multisynaptic connections causing an excess of excitation of paravertebral muscles resulting in spasm."

      NEUROVASCULAR IMPLICATIONS OF UPPER CERVICAL SUBLUXATIONS

Loss of mobility of any one or more segments of the spine correspondingly influences circulation. The resulting partial anoxia has a harmful influence upon nerve function. The artery and vein supplying a spinal nerve are situated in the foramen between the nerve and the fibrous tissue in the anterior portion of the foramen. It is unlikely that circulation to the nerve would be disrupted without first irritating or compressing the nerve because the arteries and veins are much smaller, the blood pressure within the lumen makes them resistant to compression, and nerve tissue is much more responsive to encroachment irritation.

The Vagus Nerve.   As the vagus lies almost in immediate contact with the transverse process of the atlas, rotary subluxation of the atlas may cause pressure which produces a wide range of symptoms. The syndrome produced may exhibit as nasal and sinus congestion, swallowing and speech difficulties, cardiac arrythmias, functional coronary artery spasm, gastric and intestinal colic, and other symptoms of vagal disturbance.

The Medulla Oblongata.   The medulla oblongata extends well into the lower reaches of the foramen magnum and the ligamentous ring that connects it with the atlas, thus any type of occipital or atlantal subluxation may produce abnormal pressure on this portion of the brain stem. Bilateral posterior shifting of the occiput or atlas may cause pressure upon the pyramids or adjacent olivary bodies producing a syndrome of upper motor neuron involvement characterized by a degree of spastic paralysis or ataxia. A lateral shifting of the occiput may cause pressure upon the tubercle of Rolando producing pain in the area of trigeminal nerve distribution, headache, sinus discomforts, ocular neuralgias, and aches in the jaw.

The Vertebral Arteries.   Janse relates that any cervical subluxation (particularly atlantal, axial, or occipital) producing muscle spasm may produce unilateral or bilateral constriction of the vertebral arteries resulting in circulatory impairment. A large number of equilibrium, cardiac, respiratory, cranial nerve, extrapyramidal, vagal, visual, and auditory symptoms may follow. The vertebral nerve (sympathetic) runs along the vertebral artery within the arterial foramen of the cervical transverse processes. Irritation to this nerve is considered to occur from mechanical irritation to the vertebral artery anywhere along its course producing symptoms of a vasomotor nature; eg, headache, vertigo, tinnitus, nasal disturbances, facial pain, facial flushing, and pharyngeal paresthesias. Cailliet points out that although sympathetic fibers have not been found along the cervical roots, surgical decompression of an entrapped nerve root relieves symptoms attributed to the sympathetics. The mechanism for this effect is unclear.

The Vertebral Veins and Deep Cervical Veins.   Spasm of the suboccipital muscles may cause a decided impediment of venous drainage from the suboccipital area via vertebral and deep cervical veins, resulting in a passive congestion with consequent pressure upon the sensory nerve endings in the area. This is perceived by the patient as unilateral or bilateral pain and a throbbing discomfort, and may be palpated as knotty lumps within suboccipital muscles. The condition appears to be of a reflex nature more common among people under mental tension or those who work closely with their eyes over long periods.

Cerebrospinal Circulation.   Any event that would cause constriction in the connecting area between the cerebral subarachnoid space and the vertebral canal limits the escape of cerebrospinal fluid into the inferior vertebral canal. This results in a degree of increased intracranial pressure. An atlanto-occipital subluxation may cause the dura mater of the cisterna cerebellaris to be pressed against the posterior medullary velum and partially occlude the foramina of Luschka and Magendie and interfere with the flow from the 4th ventricle. The resulting increase of intraventricular fluid accumulation may create a large variety of symptoms such as deep-seated, stubborn, "internal pressure" headaches, nausea, a tendency toward projectile vomiting, bizzare and unusual visual disturbances, and protopathic ataxias.

Headaches of Cervical Origin

It has been the experience of Markovich, the renowned neurologist, that the most common headache is the type caused by neuromuscular skeletal imbalance. He points out that "the head in the human species has changed its position from the quadruped to the erect, thereby changing the basic relationship between the cervical spine and the head, with its important functional structures, and the rest of the body." For reference, he calls attention to the quite delicate interaction and highly sensitive biofeedback or servo-mechanisms that continually make adjustments in body balance, vision, pressure, and hearing with head and neck posture. "These regulatory, homeostatic mechanisms can be disturbed by a variety of conditions, originating at any level, including the inflammation and/or irritation of the cephalic projection of the upper cervical nerves (cervico-occipital neuralgias)."

Abnormal contraction of the muscles at the occipitocervical area appears to generate a type of "ischemic irritation" that includes the entrapment of the C2 nerves (greater and lesser occipital) as they pierce the thick muscle and ascend to the back of the head to supply the back of the scalp, the temples, and the ear lobes, sending branches to the top of the head, the back of the eye, and the angle of the jaw. Differentiation of various types of headaches is shown in Table 7.7, adapted from Markovich's data. However, keep in mind that a patient may not exhibit such a clear-cut picture. For example, vascular migraine may be superimposed on occipitocervical neuralgia or episodes may be interposed, depending upon the causes involved.

               Occipito-                                        Temporo-
               cervical         Trigeminal       Vascular       mandibular
Symptom/Sign   Neuralgia        Neuralgia        Migraine       Traction 
Pain           Throbbing,       Excruciating,    Severe,        Severe,
               paroxysmal       paroxysmal       paroxysmal     dull

Quality        Muscle spasms    Stabbing         Throbbing       Dull ache

Location       Occipital        Facial           Unilateral      Facial

Aura           None             None             Visual          None

Duration       Days             Brief            Hours           Chronic

Associated     Earache          Trigger zones    Vomiting        Bruxism
symptoms       Eye pain                          Photophobia     Malocclusion
and signs      Neck pain                         Irritability    Earache
               Paresthesias                                      Joint clicks
               Anxiety
               Tinnitus
               Nausea

Neurovascular Compression Syndromes

The cervicothoracic junction area is a unique spinal area that receives far less attention than it deserves in both medicine and chiropractic. It is a common site of developmental anomalies; it is a major site of arterial, lymphatic, and neurologic traffic; and it presents the juncture of the highly mobile cervical spine with the very limited thoracic spine. This latter point is biomechanically significant.

      BACKGROUND

There are several syndromes to consider under the classification of neurovascular compression syndromes (also termed thoracic outlet or inlet syndromes), each of which may produce the symptom complex of radiating pain over the shoulders and down the arms, atrophic disturbance, paresthesias, and vasomotor disturbances. These syndromes, however, do not necessarily indicate the specific cause of the problem.

The Cervicothoracic Junction Area.   The area of cervicothoracic transition is a complex of prevertebral and postvertebral fascia and ligaments subject to shortening. It offers a multitude of attaching and crossing muscles such as the longus colli, trapezius, scaleni, sternocleidomastoid, erector spinae, interspinous and intertransverse, multifidi and rotatores, splenius capitis, splenius cervicis, semispinalis capitis, semispinalis cervicis, longissimus capitis, longissimus cervicis, and the levator costarum and scapula –all of which are subject to spastic shortening and fibrotic changes that tether normal motion.

Incidence.   The 4th and 5th decades mark the highest incidence of trouble in this area, probably because of regressive muscular changes. The incidence of disorders is more frequent in females in the order of 3:1. This is probably due to heavier upper-extremity work.

Etiology.   Trauma to the head, neck, or shoulder girdle is a common factor. In some cases, poor posture, anomalies, or muscle contractures may be involved. Reduced tone in the muscles of the shoulder girdle, by itself, has been shown to allow depression of the clavicle that narrows the thoracic outlet and compresses the neurovascular bundle. In addition, subluxation syndromes (eg, retrolisthesis) may initiate these and other disturbances of the shoulder girdle and must be further evaluated. Cervical pathology such as spinal canal or IVF encroachment by a buckling ligamentum flavum, spinal stenosis, or spurs should be a consideration. During degeneration, the dura and dentates become thickened, dura and arachnoid adhesions become prevalent, osteochondrophytes may develop from the borders of the canal or foramen –all of which tend to restrict the cord and/or nerve root during cervical motions. Osteochondrophytes near the foramen can readily compress the vertebral artery and root together.

Differential diagnosis must exclude a cervical rib etiology from infectious neuritis, banding adhesions, arthritis of the shoulder joint, clavicle fracture callus, bifid clavicle, cervical arthritis, subacromial bursitis, 1st rib subluxation and posttraumatic deformities, spinal or shoulder girdle malignacies, Pancoast's tumor of the lung apex, and cardiac disease. Aneurysms of the subclavian artery are rare.

Grieve calls attention to "the poorly recognized part played by minor unilateral joint abnormalities of the upper three or four ribs, possibly often by tension of soft tissue attachments as a consequence of cervical joint irritability at higher segments, or due to the chronic sequelae of trauma...."

      SYMPTOMS AND SIGNS

Symptoms usually do not occur until after the ribs have ossified. Two groups of symptoms are seen, those of scalenus anticus syndrome and those due to cervical rib pressure. The symptoms of cervical rib and scalenus syndrome are similar, but the scalenus anticus muscle is the primary factor in the production of neurocirculatory compression whether a cervical rib is present or not.

When symptoms are present, they are usually from compression of the lower cord of the brachial plexus and subclavian vessels such as numbness and pain in the ulnar nerve distribution. Pain is worse at night because of pressure from the recumbent position, and its intensity varies throughout the day. Tiredness and weakness of the arm, finger cramps, numbness, tingling, coldness of the hand, areas of hyperesthesia, muscle degeneration in the hand, a lump at the base of the neck, tremor, and discoloration of the fingers are characteristic. Work and exercise accentuate symptoms, while rest and elevation of the extremity relieve symptoms. Adson's and other similar compression signs will usually be positive.

Differentiation of Neural vs Circulatory Symptoms.   Compression of nerve tissue results in numbness, pain, paralysis, and loss of function. Compression of vascular structures results in moderate pain and swelling. The obstruction of circulation can result in clotting within the vessels with possible consequent infarction in the tissues supplied. These unilateral phenomena are fairly limited to the cervicobrachial distribution.

Anatomic Considerations.   Working above and behind to produce shoulder abduction and retraction (eg, painting a ceiling, repairing a ceiling fixture) will definitely cause temporary clavicle encroachment on the brachial plexus and press the subclavian artery against the scalenus medius. For many years, the cause was attributed to costoclavicular compression from shoulder depression. However, postmortum stress tests have shown the following:

1. When the arm is depressed, the clavicle moves inferior and anterior, and this widens the space between the clavicle and 1st rib.
   
   

2. When the shoulder is depressed, the upper and middle trunks of the brachial plexus are stretched tightly over the tendinous edge of the scalenus medius and the lower trunks are pulled into the angle formed by the 1st rib and the scalenus medius tendon. Most symptoms found on shoulder depression will be the result of this traction. There is no compression of the subclavian artery against either scaleni.
   
   

3. When the shoulder is retracted, the clavicle does not impinge upon the subclavian vein but the tendon of the subclavius muscle compresses the vein against the 1st rib. The middle third of the clavicle pushes the neurovascular bundle against the anterior scalenus medius, and this could cause compression if a space-occupying lesion is also present (eg, cervical rib, extrafascial band).

Clinical Compression Tests

X-ray films should always be taken before performing a cervical compression test, especially when the patient has experienced trauma or shows physical signs of advanced degeneration. It is important to rule out possible conditions that would be aggravated by any testing procedure.

      ACTIVE CERVICAL ROTARY COMPRESSION TEST

With the patient seated, he should be observed while voluntarily laterally flexing his head toward the side being examined. With the neck flexed, the patient is then instructed to rotate his chin toward the same side, which narrows the IVF diameters on the side of concavity. Pain or reduplication of other symptoms probably indicates a physiologic narrowing of one or more IVF's.

      PASSIVE CERVICAL COMPRESSION TESTS

Two tests are involved. First, with the patient seated, the examiner stands behind the patient. The patient's head is laterally flexed and rotated slightly toward the side being examined. Interlocked fingers are placed on the patient's scalp and gently pressed caudally. If an IVF is physiologically narrowed, this maneuver will further insult the foramen by compressing the disc and narrowing the foramen, causing pain and reduplication of other symptoms. In the second test, the patient's neck is extended by the examiner who then places interlocked hands on the patient's scalp and gently presses caudally. If an IVF is physiologically narrowed, this maneuver mechanically compromises the foraminal diameters bilaterally and causes pain and reduplication of other symptoms.

      SPURLING'S TEST

This is a variation of the passive cervical compression test. The patient's head is turned to the maximum toward one side and then laterally flexed to the maximum. A fist is placed on the patient's scalp, and a moderate blow is delivered to it by the other fist. The patient's position produces reduced IVF spaces, and the blow causes a herniated disc to bulge further into the IVF space or an irritated nerve root to be aggravated, thus increasing the symptoms.

      SHOULDER DEPRESSION TEST

With the patient seated, the examiner stands behind the subject. The patient's head is laterally flexed away from the side being examined. The doctor stabilizes the patient's shoulder with one hand and applies pressure alongside the patient's head with the palm of the other hand; stretching the dural root sleeves and nerve roots or aggravating radicular pain if the nerve roots adhere to the foramina. Extravasations, edema, encroachments, and conversion of fibrinogen into fibrin may result in interfascicular, foraminal, and articular adhesions and inflammations that will restrict fascicular glide and the ingress and egress of the foraminal contents. Thus, pain and reduplication of other symptoms during the test suggest adhesions between the nerve's dura sleeve and other structures around the IVF.

      CERVICAL DISTRACTION TEST

With the patient seated, the examiner stands to the side of the patient and places one hand under the patient's chin and the other hand under the base of the occiput (Fig. 7.50). Slowly and gradually the patient's head is lifted to remove weight from the cervical spine. This maneuver elongates the IVF's, decreases the pressure on the joint capsules around the facet joints, and stretches the paravertebral musculature. If the maneuver decreases pain and relieves other symptoms, it is a probable indication of narrowing of one or more IVF's, cervical facet syndrome, or spastic paravertebral muscles.

      ADSON'S TEST

With the patient seated, the examiner palpates the radial pulse and advises the patient to bend his head obliquely backward to the opposite side being examined, take a deep breath, and tighten the neck and chest muscles on the side tested. The maneuver decreases the interscalene space (anterior and middle scalene muscles) and increases any existing compression of the subclavian artery and lower components (C8 and T1) of the brachial plexus against the 1st rib. Marked weakening of the pulse or increased paresthesiae indicate a positive sign of pressure on the neurovascular bundle, particularly of the subclavian artery as it passes between or through the scaleni musculature, thus indicating a probable cervical rib or scalenus anticus syndrome.

      EDEN'S TEST

With the patient seated, the examiner palpates the radial pulse and instructs the patient to pull the shoulders backward, throw the chest out in a "military posture," and hold a deep inspiration as the pulse is examined. The test is positive if weakening or loss of the pulse occurs, indicating pressure on the neurovascular bundle as it passes between the clavicle and the 1st rib, and thus a costoclavicular syndrome.

      WRIGHT'S TEST

With the patient seated, the radial pulse is palpated from the posterior in the downward position and as the arm is passively moved through an 180° arc. If the pulse diminishes or disappears in this arc or if neurologic symptoms develop, it may indicate pressure on the axillary artery and vein under the pectoralis minor tendon and coracoid process or compression in the retroclavicular spaces between the clavicle and 1st rib, and thus be a hyperabduction syndrome.


Vertebrobasilar System Patency Tests

Although cerebrovascular accidents are extremely rare following cervical manipulation, a few cases have been reported that justify careful evaluation prior to cervical manipulation. Bergmann describes four clinical tests to evaluate the patency of the vertebrobasilar system.

      MAIGNE'S TEST

The examiner places a seated patient's head in extension and rotation. This position is held for about 15–40 seconds on each side. A positive sign is indicated by nystagmus or symptoms of vertebrobasilar ischemia. NOTE: This test is no longer considered appropriate for assessmemt, because this head position is associated with onset of stroke.

      DeKLEYN'S TEST

The patient is placed supine on an adjusting table, and the head rest is lowered. The examiner extends and rotates the patient's head, and this position is held for about 15–40 seconds on each side. A positive sign is the same as that in Maigne's test.

      HAUTANT'S TEST

The examiner places a seated patient's upper limbs so that they are abducted forward with the palms turned upward (supination). The patient is instructed to close his eyes, and the examiner extends and rotates the patient's head. This position is held for about 15–40 seconds on each side. A positive sign is for one or both arms to drop into a pronated position.

      UNDERBURGER'S TEST

The patient is asked to stand with his upper limbs outstretched, his eyes closed, and then to march in place with his head extended and rotated. The examiner should stand close to the patient during the test because a positive sign is a loss of balance.


Visual Subluxation Patterns

Clinical postural patterns reflect an individual's biomechanics that are responsive to underlying physiologic processes. This is readily appreciated clinically in many acute conditions such as the antalgic positions of sciatica, extremity dislocation, the opisthotonus of spinal meningitis, the orthopnea of asthma, the emprosthotonus of tetanus, the pleurothotonus of strychnine poisoning, the rigid abdominal spasm of peritonitis, and other postures that a patient might assume to gain relief. However, the postures reflected in chronic subluxations are much more subtle and often assumed unconsciously via proprioceptive mechanisms.

The analysis of "body language" opens the way for much subjective interpretation, and there is a tendency to point to signs that confirm one's interpretation and ignore those that do not. Nevertheless, as shown in our previous discussion of gait, many specific neuromusculoskeletal disorders can be accurately judged by observing the body in stance and in action. The interpretation of spinal distortion patterns is likewise an art, and, as in any diagnostic art, its effectiveness is in knowing the normal from the abnormal and knowing where the normal or abnormal begins and ends.

Several chiropractic researchers feel that many postural distortions are essentially massive movement of structure held in fixation by impulse bombardment initiated by neural excitement. In this sense, a visual pattern is a clue that must be confirmed by other diagnostic methods such as static and dynamic palpation and roentgenography. Other researchers feel that it is most difficult to relate specific subluxations to gross postural patterns.

In this section and especially in the future chapters on the thoracic spine and the lumbar spine and pelvis, we will offer some of the basic premises of visual subluxation patterns with the hope that it will stimulate further research in spinal analysis.

      CERVICAL SUBLUXATION PATTERNS

In normal neutral posture, the ears (semicircular canals) and eyes will be held level and parallel to the shoulders for resting orientation. Inspection is best made by using a double plumb line or a transparent grid and a foot-stabilizing device. De Jarnette feels that practically all subluxation patterns have some effect upon the occiput and upper cervical spine. Any shifting of the cranial mass (eg, tilt) will have an affect upon the cervical muscles which, in turn, alter the stabilization of the position of the head upon the cervical spine. When the occiput, atlas, and axis are in good relationship, the ears will appear level and equally prominent, reflecting equal weight distribution bilaterally and good functioning of the righting mechanism (Fig. 7.51).

      OCCIPITAL SUBLUXATION PATTERNS

When viewed from the posterior, an occiput inferior on the right due to a compressed condyle, for example, will present a head tilt low on the right. The ears will be equally prominent. A purely rotational subluxation of the occiput on the atlas will exhibit a level skull with the ear on the side of relative posteriority more prominent (Fig. 7.52).

      ATLAS SUBLUXATION PATTERNS

It is theorized by many that every atlas subluxation changes the way that the skull adapts to body posture. When there is an occipital tilt and the ear is more prominent (rotated posteriorly) on the side of occipital superiority, an ipsilateral posterior or contralateral anterior atlas subluxation is suspect (Fig. 7.53).

When the atlas is fixed in a posterior rotation on the right or an anterior rotation on the left, the right ear and mandible will be more prominent (rotated posteriorly) than the left when viewed from the posterior. The prominence of the mandible is said to be due to the subluxation's effect upon the axis.

An atlas fixed in abnormal lateral flexion will present a tipped occiput shown by unlevel ears, but the ears will be equally prominent. This is the same picture of that of a contralateral sunken condyle. With such a subluxation, reports De Jarnette, the shoulders will be level or one will be slightly low on the side of atlas inferiority if shoulder problems are associated. That is, the arm will be carried low on the side of atlas side slip.

      AXIS SUBLUXATION PATTERNS

Rotary subluxations of the axis also appear to present a typical picture. An axis subluxation changes the way the skull balances upon the atlas. If the axis is fixed posterior and inferior on the right, for example, the right ear will be rotated posteriorly and be more prominent, and the skull will be tipped inferior on the right when viewed from behind (Fig. 7.54). A unilaterally prominent mandible is thought to be an effect only in axis subluxations or when the axis influences an atlas subluxation.

      CERVICAL SUBLUXATIONS WITH SCIATICA SYNDROMES

It is not unusual to see cervical complaints associated with a case of true sciatica. In right sciatica, for example, the patient's stance may exhibit very little distortion when viewed from the posterior. If the patient is asked to raise his left heel, however, a pronounced inferior tilt of the skull on the left may appear with the dorsolumbar spine forming a mild left scoliosis. When the patient is asked to lower his left heel and raise his right heel, the dorsolumbar curve increases, an acute right dorsocervical scoliosis develops, and the occipital tilt is increased (Fig. 7.55). The raising of the right heel invariably increases right sciatic pain, according to De Jarnette, and also produces cervical pain. This manifestation is said to indicate a primary or secondary cervical subluxation, but other means will be necessary to isolate the exact segmental level of involvement.


Postural Realignment

Because the center of gravity of the head lies anterior to the occipital condyles, definite force must be applied by the posterior muscles of the neck to hold the head erect. In addition, several groups of muscles are attached directly or indirectly to the anterior part of the head, and their function adds to the force of gravity to increase the load on the posterior cervical musculature. Gelb feels that the most important anterior neck muscles are the masticatory and supra- and infra-hyoid groups, which constitute a sort of chain with the hyoid bone and mandible to which they are attached. They join the head to the shoulder girdle anteriorly.

Deformity of cervical posture can be associated with or without neck pain. As discussed, the deformity may depict curvature exaggeration, flattening, occipital tilt, rotation, and areas of complete or partial segmental fixation. If pain is present, deviation may be toward or away from the site of pain, depending upon the primary site of irritation. Keep in mind that spinal stability is essentially under the control of neuromuscular mechanisms rather than the ligaments.

Although segmental spasm or instability may not be detectable by observation, it usually becomes evident by alert dynamic palpation. Careful localization of motion and muscle strength is necessary prior to prescribing any exercise program to assist postural realignment.

      PROPRIOCEPTION

In general, the abundant proprioceptors of the vertebral column enable the brain to know where each segment is and what it is doing at any given time without visual confirmation. More specifically, data are relayed as to the degree of muscle tension and/or the length of muscles via the muscle spindles and Golgi tendon organs. Tension messages are moved through fast-conducting nerves from annulospiral endings and through higher threshold nerves from flower spray receptors in the muscle spindle. The less complex Golgi tendon organs near the musculotendinous junctions discharge impulses initiated by either muscle contraction or stretch. Other receptors near the articular surfaces relate messages about joint speed and direction of motion.

In postural realignment, as Gelb points out, restoring muscles to their physiologic resting length is a three-dimensional concept, requiring placing the origin and insertion of muscles in a correct three-dimensional relationship.

As mentioned previously, Lieb shows a number of full spine x-ray prints of severe spinal distortions greatly improved through improvement of dental occlusion. If the temporomandibular joint has such a proprioceptive influence upon posture, it is no wonder that chiropractors who specialize in solely upper- cervical or sacral correction exhibit a likewise abundance of such before-and- after exhibits inasmuch as each spinal segment is richly endowed with equal or greater receptors than that of the jaw.

      THE CERVICAL SPINAL RECEPTORS

The apophyseal joints of the cervical spine are richly innervated with mechanoreceptors and afferent fibers, endowed more than any other spinal region. Activity from the cervical articular receptors exerts significant facilitatory and inhibitory reflex effects on the muscles of the neck and both the upper and lower extremities.

Wyke points out that the patterns of "normal cervical articular mechanoreceptor reflexes are profoundly distorted when cervical articular nociceptive afferent activity is added to that derived from the normally functioning cervical mechanoreceptors." To underscore this point, he states that:

(1) manipulation of the head on the neck can produce coordinated flexion and extension movements on the paralyzed arm and leg of a hemiplegic patient,

(2) arm movement control in the absence of visual aid is considerably affected by rotation of the head, and

(3) induced unilateral local anesthesia of the cervical joints in healthy subjects produces severe postural instability, dizziness, nystagmus, and muscular incoordination. These signs and symptoms are similar to those experienced by some patients who suffer from cervical spondylosis, ankylosing spondylitis, gross fixations, and some while wearing an orthopedic cervical collar.

      RIGHTING MECHANISMS

Several head extensors arise from the lower cervical and upper thoracic vertebrae that exert an oblique posteroinferior pull on the occiput. If the line of pull falls behind the atlanto-occipital joint, a rotary movement results that tilts the occiput posteriorly and lifts the face so that the neck is hyperextended. However, if this posterior rotation of the head is inhibited by the cervical flexors (which is normal), the oblique pull tends to have a posterior translatory component when the head is anterior to the midline. This serves to bring the head back toward the vertical gravity line and into better alignment.

In addition, the longus group exerts a bowstring action on the anterior cervicals that assists in axial extension of the neck. Thus, the extensors essentially serve to return the head to the midline following flexion, but axial extension is really completed by a straightening of the cervical lordosis produced by segmental flexion. If this segmental flexion did not occur during extension, the head would rest in the neutral position facing superiorly. Simultaneously, the thoracic extensors tend to straighten the dorsal curve so that the alignment of the entire cervicothoracic region is improved (Fig. 7.56).

Chronic flexion of the lower cervicals tends to produce elongation of the posterior upper thoracic soft tissues and adaptive shortening of the anterior elements (eg, anterior longitudinal ligament, anterior disc anulus, pectorals, intercostals). This is often seen in aging where it is contributed to by degeneration of the normally fibroelastic ligamentum nuchae which helps to resist anterior deviation of the head. If this chronic flexion state occurs, cervical extension to the midline following flexion is fairly limited to increasing the cervical lordosis with little axial extension of the neck by segmental flexion. The neck angles forward, and the jaw juts out as the occiput rolls backward.

      WEAK FLEXOR STRENGTH

If weak neck flexion is evident (Fig. 7.57), emphasis should be on developing the sternocleidomastoideus, longus group, and rectus capitis anterior and lateralis. The longus group and rectus capitis group are direct antagonists to the posterior cervical muscles. They principally serve to right the neck after extension but have some activity in flexion from the neutral position. Hyperflexion, viewed as a flattened or kyphotic cervical curve, may be a manifestation of prevertebral hypertonicity, weak extensors, or a posteriorly displaced disc nucleus.

      WEAK EXTENSOR STRENGTH

Clinical development of the trapezius, semispinalis capitis, splenius group, and erector spinae should be made if weak extension strength is evident. Only in the thoracic region do the erector spinae act solely as erectors. Their contraction in the cervical region produces hyperextension with a posterior rotation of the occiput so that the chin points upward. Hyperextension, viewed as hyperlordosis, may be a manifestation of extensor hypertonicity or weak prevertebral muscles.

With two exceptions, specific isotonic exercises will not be mentioned here as the literature abounds with many good regimens. However, the rationale behind isotonic exercises following trauma deserves attention.

      THE CERVICOTHORACIC INTERRELATIONSHIP

The lateral gravity line of the body falls quite anterior to the mid thoracic region. With fatigue, there is a tendency for thoracic kyphosis to increase. Thus when cervical alignment is poor, equal concern must be given to reduce an exaggerated thoracic kyphosis for the positions of the cervical and thoracic regions are interrelated; ie, a thoracic kyphosis is usually accompanied by a compensatory cervical lordosis, and vice versa.

      EXERCISES FOLLOWING CERVICAL TRAUMA

Fisk points out that the reflex response to pain is an increase in isometric muscle activity by the small gamma fibers and a decrease in isotonic activity for the purpose of continuous resting (splinting) an irritated area. This inactivity tends to reduce impulses from the large fibers of the muscle and joint proprioceptors so that the spinal cord's "gate" is kept open, according to the theory. As prolonged inactivity leads to muscle weakness and atrophy, shortening of related connective tissues, and deterioration of articular cartilage, restoring motion and strength of a stressed region is an important clinical and biomechanical objective.

Grieve states that posttraumatic soft-tissue changes that are secondary to joint derangement or irritability become progressively prominent with age –mild during youth, severe in the elderly. The periarticular connective tissues adapt by shortening on one side of the joint and lengthening on the other side, resulting in a relatively permanent lateral flexion often accompanied by a degree of rotation. This makes chronic subluxations difficult to hold in a corrected position. However, prior to this chronic state is the state of prolonged isometric contraction mentioned above, which is readily amenable if comprehensive therapy is applied. Gillet and many others confirm this.

During the posttraumatic acute stage where there is neural excitation from the inflamed area, temporary impulse activity over the large-fibered proprioception circuits can be encouraged by movement, pressure, stretching, heat, and cold stimuli. However, heat at this stage increases swelling and movement provokes spasms, and thus are contraindicated. The logical alternative is to apply isometric exercises soon after the danger of recurrent hemorrhage has passed. This offers stretching without motion that increases circulation without engorgement and activates the large-fiber circuits, allowing a more rapid recovery. Even in chronic disorders, vigorous active motion increases intradisc pressure and can aggravate inelastic degenerated soft tissues. This would not be true for isometric exercises.

Following are several isometric exercises recommended by Fisk for the cervical spine that can readily be modified to meet varying clinical situations. They are designed to increase strength, but they also teach the patient the different perceptions of contraction and relaxation (eg, helpful in controlling chronic tension). As the head is held in the neutral position, these exercises are not contraindicated even in cases of uncomplicated hypermobility or arthritis if the patient is carefully instructed. Two or three exercise bouts daily are recommended.

Resisted Flexion.   The patient sits erect with the head straight. The patient is instructed to place clasped hands against the forehead, breathe normally, and attempt to push the head forward against the resisting hand contact (Fig. 7.58). This position should be held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise a few times.

In the alternative prone position, the patient lies face down with his forehead on a large folded towel to allow breathing in this position. The patient is instructed to tuck the chin in and firm the forehead against the towel while breathing normally. Pressure should be held for about 7 seconds; then the patient relaxes for several seconds, and repeats the exercise about twice.

Resisted Extension.   The patient sits erect with the head straight and is instructed to clasp the hands behind the head above the cervical spine (Fig. 7.59). The patient is then asked to breathe normally, keep the head straight, and attempt to push the head back against the resisting hand contact. This position should be held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise a few more times.

This exercise can also be conducted in the supine position by having the patient lie face up on a firm surface. A small firm pillow or cushion should be placed under the neck to support the head. The patient is instructed to firm the head against the pillow and firmly tuck the chin in while breathing normally. This position should be held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise a few more times.

Resisted Lateral Flexion.   The patient sits erect with the head straight. The patient places the right hand over the right ear with the fingers extending over the scalp (Fig. 7.60). The patient is then asked to breathe normally and attempt to bend the neck toward the side of contact while resisting the effort with the contact hand. Again, this position should be held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise about two or three times again. The hand positions are then interchanged, and the exercise is conducted for the other side.

This exercise can also be conducted in the lateral recumbent position. The patient lies on the side with the underside of the face against a firm pillow so that the spine is aligned in a straight line. The patient firms the head against the pillow while breathing normally. The position is held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise a few times. The patient is then instructed to lie on the other side and to repeat the exercise.

Resisted Rotation.   The patient sits erect with the head straight. The patient is instructed to place the right hand on the right temple, and then asked to breathe normally and attempt to look over the right shoulder while resisting the movement with the hand contact (Fig. 7.61). This position is also held for about 7 seconds; then the patient relaxes for several seconds and repeats the exercise two or more times. The left hand is then applied to the left temple and the exercise is conducted for the left side. This exercise can also be conducted in the supine position.

Two mild active isotonic exercises can be incorporated into the regimen when pain begins to diminish. These involve related shoulder and scapulae muscles that are often chronically tensed following cervical trauma.

Shoulder–Shrugging.   The patient stands or sits erect with the head straight, the neck aligned vertically, and the arms hanging loosely at the sides. The patient is instructed to breathe normally, elevate the shoulders as far as possible for several seconds, hold this position while the shoulders are retracted as far as possible for several seconds, and then to drop the shoulders in the retracted position and hold them there for several seconds (Fig. 7.62). The patient then relaxes for several seconds and repeats the exercise for several minutes until fatigued.

Arm Circling.   Have the patient stand erect with the head straight, the arms hanging loosely at the sides, and the feet slightly apart to widen the base of support. The patient is instructed to breathe normally, flex forward at the waist, and then bring the arms back and up in an arc from the anterior to the posterior as far as can comfortably be managed (Fig. 7.63). This arm circling should be repeated without resting intervals for as many times as fatigue will allow.

Traumatic Brachial Plexus Traction

Trauma to the brachial plexus is often seen following severe cervical lateroflexion. The effects vary from mild to severe depending upon the extent of nerve contusion, crush, or laceration. Nerve "pinch" or "stretch" syndromes may be involved which respond well to conservative care, unless nerve severance or root avulsion has occurred. The specific symptomatology, physical findings, roentgenography, and electromyography offer clues to the extent of damage, indicated therapy, and prognosis.

In brachial plexus trauma, the entire plexus or any of its fibers may be injured (refer to Table 7.5). The lateral branches of the brachial plexus lie just anterior to the glenohumeral joint. The axillary nerve lies just below the joint.

As the roots of the plexus are fixed at their origin in the spinal cord, any sudden or severe traction of the upper extremity may avulse roots from the cord or stretch the plexus to the point of tearing. Stretching injuries are common; tearing injuries are rare. Such injuries may be divided into three general types: total arm palsies, upper arm palsies (most common), and lower arm palsies. The major sensory, motor, and reflex changes involved with the brachial radiculopathies are listed in Table 7.8.

Nerve
Root        Major Sensory Disorder    Major Motor Disorder     Reflex Changes
Affected    (Hypalgesia)              (Weakness)               (Reflexes)
 C5         Lateral arm               Biceps, supraspina-      Biceps
                                       tus, infraspinatus,
                                       infraspinatus,
                                       deltoid

 C6         Lateral forearm and       Brachioradialis          Brachioradialis
            thumb

 C7         Middle finger             Triceps                  Triceps

 C8         Little finger             Wrist and finger         None
                                       flexors


 T1         Medial forearm            Intrinsic hand mus-      Finger flexors
                                       cles

      NERVE PINCH OR STRETCH SYNDROMES

Nerve "pinch" or "stretch" syndromes are common. They are often seen in the lower neck from overflexion, but the syndromes appear throughout the cranium, spine, pelvis, and extremities in many accidents. Hardly any peripheral nerve is exempt. Terms used synonymously include nerve compression, nerve contusion, nerve lesion, nerve pinch syndrome, nerve root syndrome, nerve stretch syndrome, radiculopathy, or traumatic neuritis.

A nerve stretch syndrome is commonly associated with sprains, excessive lateral cervical flexion with shoulder depression, or dislocations4. Nerve fibers may be stretched, partially torn, or ruptured almost anywhere in the nervous system from the cord to peripheral nerve terminals.

A nerve pinch syndrome may be due to direct trauma (contusion), subluxation, a protruded disc which results in nerve compression, or fracture (callus formation and associated posttraumatic adhesions). Any telescoping, hyperflexion, hyperextension, or hyperrotational blow or force to the spine may result in a nerve "pinch" syndrome where pain may be local or extending distally. Nerve pinch syndromes are less common than nerve stretch syndromes but are more serious.

      MILD OR MODERATE BRACHIAL TRACTION

After lateroflexion injuries of the neck (Fig. 7.64), a sharp burning pain may radiate along the course of one or more cervical nerves, the result of nerve contusion due to stretching. Scalenus anticus syndrome may be exhibited. This nerve stretch is often referred to as a "hot shot" by athletes. Recurring injury is common, especially in contact sports. It is not limited to sports, however, for any severe cervical lateral flexion can produce the syndrome4.

Immediate pain may radiate to the back of the head, behind the ear, around the neck, or down toward the clavicle, shoulder, arm or hand. Frequently, there is arm paresthesiae, severe arm weakness, diminished active motion, decreased biceps and triceps reflexes, forearm numbness, and cervical movement restriction. These signs and symptoms may disappear and reappear with greater severity.

Ipsilateral vs Contralateral Symptoms.   If the symptoms appear on the opposite side of the forceful bending, undoubtedly a nerve has been "pinched" within the powerful muscles dorsal to the sternocleidomastoid. If this is the case, the symptoms usually subside in a few minutes with only slight residual tenderness and paresthesia, which disappears within a few hours. On the other hand, if symptoms appear on the same side as the direction of the forceful bending, deep skeletal injury such as severe rotary subluxation, fracture, dislocation, or nerve compression may be involved4.

      ROOT AVULSION

A similar but more severe nerve injury is that to the brachial plexus or its roots which is usually caused by a fall on the shoulder, a blow to the side of the neck, forceful arm traction, or a combination of these mechanisms. The injury is essentially caused by acute shoulder depression that stretches the brachial plexus especially in the supraclavicular area. The effect may be root tear near the vertebral foramen, spinal cord damage, dural cuff leaks of cerebrospinal fluid, and/or vertebral fracture or dislocation. During avulsion, the spinal cord itself is infrequently damaged and contralateral cord symptoms are found. Such severe manifestations are rarely seen in the well-conditioned patient where the picture is usually limited to pain radiating into the arm and/or hand.

      PHYSICAL FINDINGS

Painstaking examination is required as multiple nerve injury, related tendon or other soft-tissue damage, and fractured bones may complicate the picture. The immediate site of injury should be first investigated, followed by the part's general appearance, voluntary motion, reflexes, and vasomotor changes. Trophic lesions of the joints, muscles (atrophy), skin, and nails are common in the late stage4. They usually blend and are explained as the results of vasomotor changes. In addition to motor and sensory loss, the response to electrical stimulation should be evaluated.

Damage to an individual peripheral nerve (eg, trauma) is characterized by:

(1) flaccid, atrophic paralysis of the muscles supplied by the involved nerve and

(2) loss of all sensation, including proprioception, in the skin areas distal to the lesion. When partial destruction to various peripheral nerves occurs, the effects are usually more prominent in the distal extremities. The condition is characterized by muscular weakness and atrophy and poorly demarcated areas of sensory changes. Unless severe nerve injury has occurred to the nerve or its attachment at the cord, chiropractic care offers a conservative approach to case management.

In ulnar nerve damage, sensation is lost on the medial side of the hand, including the little finger and medial half of the ring finger. In median nerve damage, sensation of the remainder of the anterior surface of the hand is lost. However, motor involvement is the main feature as sensory loss is often obscured by overlapping innervation. As time goes by after severe nerve injury, the affected part assumes a posture and atrophy peculiar to the particular nerve involved; for example, "wrist drop" with the radial nerve, "claw hand" with the ulnar nerve, "flat hand" with the median nerve, and "ape hand" with the ulnar and median nerves.

      ROENTGENOGRAPHY

Films are often negative in mild to moderate cases. In severe cases, a unilaterally locked facet may be viewed as a positive sign of dislocation. This is caused by one facet displacing while the opposite side remains in position. It is easy to miss on physical examination because normal neck movements usually do not increase the dislocation4.

On the standard A–P view, the spinous processes above the luxation will be out of alignment with the processes below the lesion. Displacement will be ipsilateral on the side of the locked facet.

On the lateral view, displacement is usually obvious even though it may not be pronounced. The facets inferior to the lesion are superimposed (often seen as one). Superior to the lesion, the facets are offset and viewed as being one in front of the other (bow-tie sign). In recurring cases, such as in football players, symptomatic or asymptomatic spur formation on cervical vertebrae is common.

      CASE MANAGEMENT

The effect of treatment depends largely upon early recognition of the nerve injury with removal of aggravating factors. Management consists of support to the affected part in the functional position and normal regimens for severe nerve contusion. As with most injuries, associated or concomitant subluxations or fixations must be adjusted to aid recovery, and sites of abnormal reflexes and stasis must be normalized.

Cold packs and/or especially ice massage are applicable in the acute stage to reduce adjacent swelling and bleeding. Vapocoolant sprays to isolated trigger points and meridian therapy often produce rapid spasm reduction of affected areas. After the acute stage subsides, massage, electric stimulation, progressive exercises, and reflex technics may be utilized. Heat, massage, passive exercises, and nutritional control are also helpful during rehabilitation.

Prevention of aggravation requires correction of associated subluxations, strengthening cervical muscles, wearing a plastic roll within a stockinet as a cervical collar or applying a Thomas-type collar, and avoiding dangerous movements at work or play.

A reaction of nerve degeneration added to typical sensory and motor loss is indicative of complete anatomic or physiologic nerve damage usually requiring surgical intervention. If surgery is required, careful attention must be given to postoperative chiropractic care directed to maintaining as much as possible normal joint flexibility, fascia and ligamentous resiliency, muscle elasticity, and adequate nutrition to all tissues involved. Some postoperative improvement can be anticipated. Approximately one month before it can be detected clinically, an electromyogram will exhibit reinnervation.

      PROGNOSIS

If the lesion is due to stretching, contusion, or partial tearing, the prognosis is good and complete recovery may usually be anticipated. The prognosis is usually poor in avulsion from the cord. Fortunately, most injuries are neurapraxias, and full recovery can be anticipated in time.

When a peripheral nerve fiber is permanently destroyed by either trauma or disease, the portion distal to the nerve cell body completely degenerates, and the fiber loses its myelin sheath in the process. In time, the isolated fiber stump tries to sprout in random directions in an attempt to make a bridge with the severed portion of the nerve. Some of these sprouts may, apparently by chance, cross the gap and enter neurolemmal tubes leading to a peripheral motor or sensory terminal. Function may be restored if the connection is a suitable match. Fibers in the spinal cord and brain do not regenerate effectively; however, recent evidence discloses that some regeneration can occur.


Structural Fixations

A vertebra may be fixed in a position it could normally occupy during any phase of physiologic movement; thus a fixated segment is hypomobile, enjoying a less than full range of movement but still occupying a position possible to a normal motion unit. In a typical vertebral fixation, nothing may be subluxated or "out of place." On the contrary, the involved segment is too much "in place"; ie, the full expression of movement is blocked. Such states are the most common form of chronic subluxation seen in chiropractic.

While fixations are not visible on static x-ray films, motion palpation reveals the subtleties of incomplete fixations as a loss of "joint play," an erratic jumpy motion at some point during the arc of movement, or as a paradoxical movement where the involved segment moves in the opposite or divergent direction to the overall spinal movement.

      JOINT PLAY

Every healthy articulation (spinal or extraspinal) can be moved through its planes of normal motion actively and passively without causing pain. In addition to this, there is an accessory movement called "joint play" that cannot be influenced except passively. Joint play can be defined as that degree of joint movement allowed passively that cannot be achieved through voluntary effort (refer to Fig. 6.77).

Although joint play cannot be produced by phasic muscle contraction, voluntary action is greatly influenced by normal joint play. This is because the loss of joint play results in a painful joint that becomes involuntarily protected by secondary muscle spasm (splinting). Thus, motion palpation to detect restricted joint play is an important part of the biomechanical examination of any painful and spastic axial or appendicular joint.

When normal joint play is restored to a joint via corrective manipulation, the pain caused by restricted joint play soon subsides and the associated muscle spasm relaxes. This manipulation usually requires a carefully directed dynamic thrust in the plane of restricted motion.


      MOTION PALPATION OF THE CERVICAL SPINE

The objectives of dynamic palpation are to note:

(1) normal and abnormal segmental motion and

(2) motion restrictions, "jumps," erratic gliding, and motion smoothness. Thus, bilateral motion quantity and quality are concerns.

During motion palpation, each cervical vertebra is palpated during flexion, extension, rotation, and lateral flexion to assess segmental mobility. The amount of motion in any particular joint depends upon:

(1) the shape of the joint surface,

(2) the laxity or tautness of supporting ligaments, and

(3) the condition of the related musculature. Essentially, the extent of movement below the axis is dependent upon ligamentous and muscular laxity and the distortion and compressibility of the IVD's.

Atlanto-occipital Palpation.   Spinal motion palpation usually starts with the articulation between the occiput and the atlas. Flexion, extension, rotation, and lateral flexion should be evaluated.

1. Flexion-extension.   In cervical extension, the atlas projects forward as a unit; in flexion, the atlas rolls backward. The examiner's palpating finger is placed within the space between the tip of the transverse of the atlas and the ramus of the jaw, while the supporting hand on the patient's scalp forces the patient's head into extension so that the chin moves up and forward and then into flexion so that the chin moves down and inward. Note the change in space underneath the palpating fingertip. The space should normally open on extension and close on flexion. These movements, conducted several times, should be restricted as much as possible to the upper cervical area and tested bilaterally.
   
   

2. Rotation.   In rotating the atlas horizontally anterior without flexion or extension, there is normally a wider separation between the jaw and the transverse process. That is, the transverse-jaw space opens as the head is turned away from the palpating finger and closes as the head moves towards the palpating finger. This is a difficult motion to palpate because of the bulging of the sternocleidomastoideus.
   
   

3. Lateral flexion.   The tip of the palpating finger is placed deep within the small space between the tip of the C1 transverse process and the mastoid process of the occiput. As the support hand rocks the patient's scalp laterally, the space change should be noted as the ipsilateral occipital condyle rolls laterally up and out on the atlas as the scalp moves away from the palpating finger and down and in as the head is laterally flexed toward the palpating finger. On flexion to the right, the transverse-mastoid space should open on the left and close on the right.

Differentiating Atlanto-occipital Muscular and Ligamentous Fixations. The tip of the palpating finger is placed under the posterior occiput, midway between the occipital notch and the mastoid process. Some examiners prefer to cup the atlas in the web of the palpating hand so that the thumb palpates one side while the first finger palpates the other side. The supporting hand rocks the patient's head into flexion and extension. If a stubborn ligamentous fixation is present, the fibrous tissues will palpate as a hard mass that does not change texture during motion.

Posterior and Anterior Atlanto-occipital Fixations.   During A–P examination, the ramus of the jaw may be felt to flip distinctly superior rather than rolling anterior. Gillet believes this hinge-type motion (rather than a rolling motion) is the result of hypertonicity of the rectus posterior minor muscle, either unilateral or bilateral, that produces restricted motion of the posterior atlas but free motion of the anterior atlas. If this is the case, forced motion will produce a shear force. On the other hand, if the anterior muscles are hypertonic, the anterior aspect of the condyle(s) will be compressed against the anterior lateral mass(es) of the atlas, while the posterior aspect opens. This can be palpated on forced motion by placing the palpating finger in the posterior aspect of the transverse-mastoid space while the patient's head is forced into extension and flexion.

Atlantoaxial Palpation.   The most important movements to evaluate here are rotation and lateral bending:

1. Flexion-extension.   The palpating finger is placed in the space between the posterior tubercle of the atlas and the spinous of the axis. This space should open on flexion and close on extension, and the posterior tubercle should become more apparent on flexion and be lost to touch on extension.
   
   

2. Rotation.   The tips of the first three fingers are placed horizontally in the suboccipital space so that the first finger firmly presses against the occipital notch and the third finger rests lightly on the tip of the C2 spinous process. The free hand is used to rotate the head. During rotation, several degrees of atlas rotation should take place before the axis begins to move. Normally, the third finger will slip upon the spinous process of the axis as the head is rotated because the head moves 1 cm or more prior to axial motion. Bilateral atlantoaxial fixation is indicated if the axis immediately follows the movement of the head (essentially the atlas), noted by the third finger not gliding over the process of the axis. If unilateral (pivotal) fixation is present, this situation will occur during rotation to one side but not to the other, and the center of movement will be at the point of fixation rather than at the odontoid. If the axis is fixed unilaterally, rotary movement will also be felt on the free side during A–P motion.
   
   

3. Lateral flexion.   It has been Gillet's experience that abnormal lateral flexion of the atlas on the axis is affected most by hypertonicity of the intertansversarii and/or the upper aspect of the longus coli. Motion restricted can be determined by placing the tip of the palpating finger in the posterolateral space between the transverse processes of the atlas and axis. Space changes are checked during both lateral flexion and A–P motion. While intertransversarii hypertonicity restricts lateral bending, a small degree of lateral gliding of the atlas on the axis is usually allowed. This does not appear to be true when hypertonus of the longus coli exists.

Axis and Lower Cervical Palpation.   Flexion, extension, rotation, and lateral bending motions should be evaluated for each segment when possible.

1. Flexion-extension.   In flexion and extension, the interspinous spaces should be felt to open and close.
   
   To check A–P joint play of any cervical vertebrae, place the thumb and middle finger on the articular pillars of the vertebra being examined. With the other hand (stabilizer), cup the patient's forehead in the palm. Place the patient's neck in full passive flexion and then extension, and check for additional joint play at the end of each passive motion by applying digital pressure with the contact hand.
   
   

2. Rotation.   Areas of rotary fixation are quite easily determined except in the athlete with extremely heavy posterior neck muscles. The patient rotates the head as far as possible in one direction. Then the palpating fingers slide down the posterolateral aspect of the transverse processes. The contact is made by the tips of the palpating fingers pushing the belly of the sternocleidomastoideus anterior. A firm "bulge" will be evident over the restricted transverse, and this is usually attributed to a hypertonus multifidus or intertransversarii muscle.
   
   To check rotational joint play of any cervical vertebrae, take the same contacts as above. Rotate the patient's head to one side and then to the other, checking for additional joint play at the end of maximum passive rotation.
   
   

3. Lateral flexion.   The axis is palpated in lateral bending as moving away from the flexion. To evaluate lateral gliding of the axis, the examiner's thumb is firmly pressed against the posterolateral aspect of the C2 spinous process, while the supporting hand moves the patient's scalp in wide lateral flexion.

The third cervical may be palpated during lateral bending, flexion, and extension much like the axis, noting the separation and closure of the spinous process on A–P motion and rotation and lateral bending by palpating the posterolateral space between the transverse processes. Rotation reveals minimum motion and is difficult to palpate. The same procedure is applied to the rest of the cervical spine. However, palpation in the middle and lower cervical region is difficult because the palpating finger is usually against tender nerves. Some examiners prefer an interlaminae contact.

To check lateral flexion joint play of any cervical vertebrae, take an index finger contact on the lateral aspect of the vertebra being examined. Laterally flex the patient's head over the contact finger, and check for additional joint play at the end of passive motion.


Common Types of Middle and Lower Cervical Fixation.   The two most common types of fixation in this area are those of the interspinous and covertebral areas:

1. Interspinous fixation.   Hypertonicity of one or more extensors tends to bind spinous processes together so that a local lordosis is formed. This condition, often found at the C3–C4 level, is palpable when the spinous processes refuse to open during forced flexion. It is also often evident on lateral flexion roentgenographs where two or more vertebrae do not follow the curve of the neck as a whole.
   
   

2. Covertebral articular fixation.   Fixation is common at the lips of the joints of Luschka by longus colli hypertonicity, ligamentous shortening, and exostosis. Restricted motion can often be determined during A–P motion from the anterolateral by carefully pushing the esophagus lateral with two palpating fingers and evaluating the motion of the vertebral bodies. If during passive extension it is found that the patient's neck stops sharply at a point far short of normal extension, Gillet refers to this "brick wall" sign of strong restriction as an indication of cervical osteophytes. This is a classic sign of chronic degeneration found in the cervical joints of the elderly presenting a thin, "dry" cervical spine. These fixations usually produce a chronic brachialgia.

      UPPER CERVICAL FIXATIONS FROM HYPERTONICITY

Because the cervical muscles are directly involved with the righting reflex, their stretch reflexes are normally relatively hyperactive. Chronic multimuscular contractions in the suboccipital area will often palpate as an area of tough ligamentous fixation, and, if this is the case, they should be considered as ligaments therapeutically.

Common Sites of Muscular Fixation.   There are six major pairs of anterior and posterior muscles operating in the atlanto-occipital area to produce A–P rocking of the occiput on the atlas and atlas rotation. Any one or more of these muscles can be in a state of hypertonicity, thus maintaining the numerous types of upper cervical subluxation.

1. Obliquus capitis superior.   This muscle joins the transverse process of the atlas to the occiput. Hypertonicity restricts contralateral extension and lateral flexion (Fig. 7.65).
   
   

2. Obliquus capitis inferior.   This muscle spans between the spinous process of the axis and the transverse process of the atlas. Hypertonicity will tend to fixate the atlas-axis articulation, especially on rotation toward the opposite side. The spinous process of the axis will often be palpated as being distinctly pulled laterally.
   
   

3. Rectus capitis posterior (minor and major).   The minor arises from the posterior tubercle of the atlas and the major from the spinous process of the axis. Both insert at the occiput and function in extension of the head upon the neck. Hypertonicity produces approximation of the C2 spinous process and the occiput, thus increasing upper cervical lordosis and restricting flexion mobility. Gillet feels this state is usually the manifestation of a lower fixation (eg, anterior thoracic).
   
   

4. Rectus capitis anterior and lateralis.   The anterior part originates on the lateral mass of the atlas and inserts in the basilar part of the occiput. The lateral aspect arises from the transverse process of the atlas and inserts at the jugular process of the occiput (See Fig. 7.9). Both serve to flex and support the head. Hypertonicity restricts extension.
   
   

5. Longus colli.   Hypertonicity of the cervical branches of this muscle produces a greater fixed space between the C2 spinous process and the occiput. The picture is the converse of rectus capitis posterior shortening.
   
   

6. Longus capitis.   This muscle arises from the transverse processes of the C3–C6 vertebrae and inserts at the basilar portion of the occiput. It functions in head flexion.

Occipitoaxial Locking.   Although the occiput and axis are not contiguous, hypertonicity of the rectus capitis major posteriorly and/or longus colli anteriorly will tend to firmly bind these structures together. In the neutral position, a hypertonic rectus capitis major pulls the occiput against the spinous of C2, as seen in normal extension. This state remains palpable even in forced flexion by placing a palpating finger in the space behind the usually unpalpable posterior tubercle of the atlas. Conversely, a hypertonic longus colli tends to force the occipitoaxial space open, frequently allowing the posterior tubercle of the atlas to be palpated in the neutral position. This space does not appreciably close on forced extension, as the occiput and axis will move as a fixed unit if locked.

Secondary Fixations.   Gillet feels that, although upper and lower cervical hypertonicities of the short muscles (eg, occipitoaxial locking) are quite common, they are often secondary effects from lower sites of fixation. Thus, they return quite quickly after correction unless the primary fixation is released.

      LOWER CERVICAL FIXATIONS FROM HYPERTONICITY

The A–P Prime Movers.   Hypertonicity of the sternocleidomastoideus (Fig. 7.66) and related flexors forces increased mobility upon the posterior arches, a decrease in height of the anterior anulus, and restricts extension. The disorder may be either unilateral or bilateral. This is the converse of generalized posterior cervical muscle shortening that restricts flexion, decreases posterior IVD thickness, and forces increased mobility upon the anterior anular fibers. Either anterior or posterior hypertonicity tends to decrease the normal range of rotation but less so than hypertonicity of the rotatores (Fig. 7.67).

The Intertransverse Muscles.   Due to the plane of the cervical facets, unilateral hypertonicity produces lateral flexion of the superior vertebra and a degree of rotation of the inferior vertebra. Bilateral hypertonicity exaggerates the cervical lordosis. If the curve has previously flattened, the kyphosis will be exaggerated.

The Interspinous Muscles.   These muscles are often well developed in the cervical area. Bilateral hypertonicity produces a motion-unit lordosis that, more often than not, is asymptomatic except on deep palpation.

The Multifidi and Rotatores.   The weak cervical multifidi are especially prone to fixation in the C4–C6 cervical area, while the rotatores are frequent sites at the C2–C3 levels.

      LOWER CERVICAL FIXATIONS FROM LIGAMENT SHORTENING

The Anterior Longitudinal Ligament.   This appears to be the only frequent site of adverse ligamentous fixation in the lower cervical region (See Fig. 7.21).

The Intertransverse Ligaments.   These ligaments are infrequent sites of pathologic fixation. They are usually palpable when the relaxed neck is laterally flexed.

      MOTION MEASUREMENTS IN CERVICAL FIXATIONS

Several investigators of cervical mobility have noticed that it is quite difficult to determine the effects of specific fixations on the overall mobility of the cervical region because each fixation is accompanied by an area of hypermobility. It appears on cineroentgenography that a degree of exaggerated mobility is capable of compensating for fixation restriction wherein the overall measurement appears normal.

Gillet states that when the degree and number of fixations are such that there is no place for areas of consequent hypermobility, the overall ranges of movement are much more visibly restricted. This is especially true when the fixations are bilateral; in which case, more gross methods can be used in assessment.

The degree of extension possible is calculated by Gillet by pulling the head and neck backward to a maximum degree short of pain and inspecting the patient in profile. An imaginary line is then made at the posterior edge of the ear, and a mark is made with a skin pencil at the point where this line cuts the shoulder. There will usually be a gain in mobility of a few centimeters after an adjustment. In nonosteophytic types of fixations of principally a muscular nature, the postadjustive change will be much greater.

The examiner measures the degree of anterior flexion by placing his chest against the patient's mid dorsals to prevent thoracic movement and then directing the patient's head down and forward to a maximum short of pain. While the patient is in this position, the C7 spinous process is marked with a skin pencil. Then with a spirit level placed horizontally from that point to the ear, another mark is made where the horizontal line cuts the imaginary ear line. In a normally mobile neck, this point should meet the top of the auricle while the line in a stiff neck will cut its base.

This offers the examiner two measures, one indicating restriction caused by fixation at the anterior aspect of the cervical spine and the other at the posterior aspect. One of these is usually greater than the other.

Gillet's research has shown that nearly all partial fixations found in the cervical region are secondary to more primary fixations in the remainder of the spine or in extraspinal joints (disappearing upon correction of the primary factors). The effects of these extracervical primary factors upon cervical rotation and lateral flexion mobility can also be measured. The examiner sits directly behind the patient and reaches forward, grasping the occiput of the patient in one hand and the chin in the other. The head of the patient is then rotated to an easy maximum with care taken not to force the patient's shoulders around at the same time. The examiner may hold the patient's shoulders back with his forearm. Then, holding the head in rotation with one hand, a point is drawn with a skin pencil on the patient's shoulder exactly under an arbitrary point to the ear. The head is then turned to the opposite side and a point is made on the other shoulder, exactly under the one made on the same point of the other ear. A third point is then marked on the C7 process, and the space between the two exterior points and the C7 will indicate the relative degree of mobility in rotation of the whole cervical spine. In a fairly supple neck, this distance should not be more than a centimeter; in a stiff neck, it may be up to 4 cm. These measurements can be used for all fixations in the cervical area; but because of the lesser degree of normal movement between the occiput and atlas, it will not be influenced as much by fixation there.

Some partial fixations hinder lateral flexion more than any other movement. This is especially true of the uncovertebral fixations which are quite frequent in the C4–C6 region. To measure these fixations, the patient's head is flexed to the side to an easy maximum with one hand on the skull and the other on the ipsilateral shoulder to prevent it from following the movement. Again, an arbitrary point on the ear is selected and a mark is made on the shoulder directly under it while the patient's neck is in maximum lateral flexion. The same is done in lateral flexion of the opposite side, and, as in rotation, the space between the two shoulder points and the C7 process is measured. In a supple neck, the points should be quite close to the C7 spinous and may overlap it. In a stiff neck, this space may measure up to 3 cm on either side, but this is rare. Naturally, painful conditions of the neck influence the above measurements. In fact, they may be very difficult to measure in cases of acute torticollis.

Gillet found that most patients seemed to turn their heads less to the right than to the left, and no fixation could be found to be responsible for this anomaly in mobility. It appears to be normal for right-handed people, and the opposite appears true for left-handed people.


Cervical Disc Disorders

Grieve points out that the clinical picture of cervical disc disorders is typically a combination of "a hard osseocartilaginous spur, produced by the disc together with the adjacent margins of the vertebral bodies." Furthermore, "the mechanism by which pain and disability originate in the neck region," contends Cailliet, "can be considered broadly to result from encroachment of space or faulty movement in the region of the neck through which the nerves or blood vessels pass." This encroachment of space or faulty movement commonly comprise apophyseal subluxation with osteophyte formation, contributing to, or superimposed upon disc degeneration and/or protrusion. This occurs most frequently in the C4–C6 area.

      DISC DEGENERATION

The cervical spine is readily subject to degenerative disc disease because of its great mobility and because it serves as a common site for various congenital defects. Bone changes are more common posteriorly in the upper cervicals and anteriorly in the lower cervicals. Cervical degenerative changes can be demonstrated in about half the population at 40 years of age and 70% of those at 65 years, many of which may be asymptomatic.

Various factors, individually or in combination, may be involved in initiating the process. These factors include trauma, postural and occupational stress, biochemical abnormalities (eg, hydration, mucopolysaccharide, collagen, lipid changes), biologic changes (eg, aging), autoimmune responses, psychophysiologic effects (eg, the sodium retention of depression), and genetic predisposition (eg, identical development in twins).

      DISC ENCROACHMENT

Pure encroachment of a disc upon the spinal canal or IVF as seen in the lumbar region is not frequently seen in the cervical area. This is due to several reasons. First, the posterior longitudinal ligament completely covers the dorsal aspect of the disc and not just its central aspect as in the lumbar region. This ligament is also stronger and thicker (double-layered) in the cervical area. Second, the thickness of the cervical disc is so designed that it is wider anteriorly and narrower posteriorly, and horizontally wider and stronger in its posterior aspect. This tends to somewhat minimize posteriorly directed movement of the nucleus. Third, the dorsolateral disc herniation necessary for nerve root compression is minimized by the lips of the covertebral joints, which form a hard wall between the anulus and the exiting nerve.

      CLINICAL SIGNS AND SYMPTOMS

The discs below C3 exhibit a higher incidence and the greatest severity of herniation. The C5 disc is the most frequently involved, followed by the C6 disc. The C2 disc is the least frequently involved.

In acute disorders, interspace narrowing, straightening of the cervical curve, and instability may be the only roentgenographic signs present. Instability will be most evident as aberrant segmental movement in comparative lateral films made during full flexion and extension. If the protrusion is central, cord signs and symptoms present such as lower extremity spasticity and hyperactive reflexes. Sensory changes are rarely evident. The gait may be ataxic. If the protrusion is posterolateral, the nerve root will be involved rather than the cord.

Several structural changes occur in chronic disorders. The vertebral bodies involved become elongated, the normal cervical lordosis flattens, the anterosuperior angle of the vertebral bodies becomes rounded, the involved body interspace narrows, the total height of the neck is reduced, and the inferior apophyseal facet above tends to subluxate posteriorly on the superior facet below and erode the lamina. Posterior osteophytes form at the disc attachment peripherally, often compromising the IVF's and vertebral canal. This may be noted by narrowing of the A–P dimension of the spinal canal in lateral films and foraminal encroachment on oblique films. These signs most frequently occur at the C6–C7 level. Anterior osteophytes are considered the result of abnormal ligamentous stress rather than part of the disc degeneration process. They occur most frequently below the C4 level, as do alterations of the covertebral joints.

Neurovascular Signs.   The specific neurovascular manifestations of acute cervical disc herniation are:

C2 disc protrusion (C3 nerve root level):   posterior neck numbness and pain radiating to the mastoid and ear. The reflexes test normal.

C3 disc protrusion (C4 nerve root level):   posterior neck numbness and pain radiating along the levator scapulae muscle and sometimes to the pectorals. The reflexes are normal.

C4 disc protrusion (C5 nerve root level):   lateral neck, shoulder, and arm pain and paresthesia, deltoid weakness and possible atrophy, hypesthesia of C5 root distribution over middle deltoid area (axillary nerve distribution). The reflexes test normal.

C5 disc protrusion (C6 nerve root level):   pain radiating down the lateral arm and forearm into the thumb and index finger, hypesthesia of the lateral forearm and thumb, decreased biceps reflex, biceps and supinator weakness.

C6 disc protrusion (C7 nerve root level):   pain radiating down the middle forearm to the middle fingers, hypesthesia of the middle fingers, decreased triceps and radial reflexes, triceps and grip weakness.

C7 disc protrusion (C8 nerve root level):   possible pain radiating down the medial forearm and hand, ulnar hypesthesia, intrinsic muscle weakness of the hand. However, these symptoms are uncommon. The reflexes are normal.

The above symptoms will vary depending upon the direction of the disc bulge; eg, upon the nerve root, IVF vessels, spinal cord, or combinations of involvement. In some acute and many chronic cases, numbness may manifest without pain. In acute disorders, these cervical signs may be confused with those of shoulder or elbow bursitis, epicondylitis, or subluxation, especially when no local cervical symptoms exist.

Vertebral Artery Compression.   Associated subluxation and osteophyte development may produce vertebral artery compression, especially if a degree of arteriosclerosis is present (See Fig. 6.12). Symptoms of unsteadiness, dizziness, and fainting spells will occur especially when the head is rotated to the opposite side.

Autonomic Involvement.   Vague autonomic symptoms may be exhibited such as dizziness, blurred vision, and hearing difficulties. These can usually be attributed to involvement of the plexus around the vertebral artery or intermittent disruption of the blood flow.

Lhermitte's Sign: With the patient seated, flexing of the patient's neck and hips simultaneously with the patient's knees in full extension may produce sharp pain radiating down the spine and into the upper or lower extremities. When pain is elicited, it is a sign suggesting irritation of the spinal dura matter either by a protruded cervical disc, tumor, fracture, or multiple sclerosis.

      THERAPEUTIC CONSIDERATIONS

Adjustive treatment consists of specific manipulation performed with manual or mechanical traction at the involved motion units to free impinged synovial fringes, reduce articular and disc displacements, and free areas of fixation. This should not be performed with the neck in extension, and extreme care must be taken to avoid joint, nerve, cord, or vascular insult.

Adjunctive therapy includes immobilization of the neck with a cervical collar, sleeping with the head between sand bags or in traction, heat (diathermy, ultrasound, infrared, moist hot packs) to reduce pain from muscle ischemia, trigger point therapy, and periodic bed rest with cervical traction by an orthopedic pillow. Gross vibrations (eg, long-distance automobile riding) and neck extension (eg, overhead work) must be avoided. Goodheart feels that nutritional supplementation with 140 mg of manganese glycerophosphate six times daily has proven helpful. Isometric exercises during rehabilitation to lengthen the cervical spine and strengthen the cervical muscles are extremely beneficial.

Referral for radical treatment is generally made if one of the following occurs:

(1) conservative treatment fails to produce remission of symptoms;

(2) attacks reappear after a short period; (3) severe nerve root compression with paralysis, indicated by muscle wasting and/or a persistent sensory deficit, has developed.

Cervical Spondylosis

Three not infrequent diseases of the cervical spine with biomechanic implications are spondylosis, rheumatic spondylitis, and ankylosing spondylitis. In each of these conditions, severe subluxation is a cardinal manifestation.

Cervical spondylosis is a chronic condition in which there is progressive degeneration of the IVD's leading to secondary changes in the surrounding vertebral structures, including the posterior apophyseal joints. It is the result of direct trauma (ie, disc injury), occupational stress, aging degeneration, or found in association with and adjacent to congenitally defective vertebrae.

      PATHOLOGY

Spondylosis may produce compression of either the nerve root or spinal cord. During the degenerative process, intradisc pressure decreases, the anulus protrudes, and the end plates approximate due to reduction of disc thickness. As the disc protrudes, it loosens the attachment of the posterior longitudinal ligament and this allows the anulus to extrude into the cavity formed between the posterior vertebral body and the ligament. This portion of the anulus, in time, becomes fibrous and then calcifies (Fig. 7.68). It is for this process that posterior osteophytes prevail in the cervical and lumbar regions, while anterior spurs are more common to the dorsal spine.

      INCIDENCE

Incidence is high in the second half of life with increasing severity in advancing years; 60% at 45 years, 85% at 65 years. The degenerative process, which may or may not progress, appears greatest in those segments below the maximum point of the lordosis because of the static and kinetic forces in the upright posture. It is most often seen at the C5 level, and next in frequency at the C6 level.

      ETIOLOGY

Pre-existing spinal stenosis, a thickened ligamentum flavum, a protruding disc, and spur formation not uncommonly complicate the picture of cervical spondylosis. There is almost no correlation between the degree of perceived pain in the neck and the degree of arthritic changes noted in x-ray films. The weight of the head in faulty posture (eg, exaggerated dorsal kyphosis and cervical lordosis) along with activity stress may contribute to chronic degenerative spondylosis often superimposed upon asymptomatic anomalies. Clinically, a vicious cycle is seen in which subluxation contributes to degenerative processes and these processes contribute to subluxation fixation.

Jeffreys points out that there appears to be a correlation of cervical spondylosis to carpal tunnel syndrome, lateral humeral epicondylitis, cervical stenosis, and low back and/or lower extremity osteoarthritis.

      SIGNS AND SYMPTOMS

The onset is usually rapid and insidious but may be subjectively and objectively asymptomatic. The classic picture is one of a middle-aged person with greatly restricted cervical motion with marked muscle spasm, positive cervical compression test, insidious neck and arm pain and paresthesia aggravated by sneezing or coughing, acute radiculopathy from disc herniation, and usually some muscle weakness and fasciculations. Generally, central herniation produces local neck pain while lateral herniation produces upper extremity pain.

Whiting lists the manifestations that develop in spondylosis to also include neck crepitus, subjective or objective; local neck tenderness; headaches; neck pain radiating to the scapulae, trapezius, upper extremities, occiput, or anterior thorax; extremity muscle weakness; paresthesia of the upper and/or lower extremities; dizziness and fainting; impaired vibration sense at the ankle; hyperactive patellar and Achilles reflexes; and positive Babinski responses.

      ROENTGENOGRAPHIC CONSIDERATIONS

Due to the constant weight of the head, postural strains, occupational in sults, degrees of congenital anomalies, and posttraumatic or postinfection effects with or without an associated disc involvement, the development of chronic degenerative spondylosis offers some distinct progressive characteristics:

(1) flattening of the cervical spine from muscular spasm and adhesion development,
(2) A–P fixation and restricted mobility,
(3) thinning of the atlanto-occipital and atlantoaxial articular plates resulting in motion restriction,
(4) middle and lower cervical disc wearing and thinning which narrows the IVF's,
(5) disc weakness encouraging nuclear shifting and herniation contributing to nerve encroachment,
(6) osseous lipping and spurs with extensions into the IVF's, and
(7) infiltration and ossification of paravertebral ligaments adding to inflexibility and pain upon movement.

The Davis series may suffice, but special views, tomography, myelography, or discography may be necessary for firm diagnosis.

Nelson believes that head weight and postural strains are overemphasized as it has often been established clinically that "unless overt trauma can be shown, most neck problems are the result of reflex vasospasm where the reflex originates in the viscera below the diaphragm. Everyone would be affected if weight of the head and postural strains were common causes." Regardless of the merit of this controversial concept, it is important to avoid the pitfall of assuming that all the patient's symptoms involving the neck and upper extremities are caused by a cervical spondylosis when it is found radiographically. Cervical spondylosis is common, and symptoms may thus be associated with unrelated neurologic disease which may coexist with the spondylosis, making the diagnosis more difficult.

      CASE MANAGEMENT AND PROGNOSIS

Whiting brings out that it is fortunate that most people with cervical spondylosis are asymptomatic because there is no correction per se. Treatment is aimed at reducing symptoms of neurologic and vasoneurologic involvement or treating the soft-tissue injury superimposed on the pre-existing spondylosis. A trial of conservative treatment is preferred in cases demonstrating signs of either cervical radiculopathy and/or myelopathy.

There is a natural tendency for a patient suffering with symptoms of radiculopathy related to cervical spondylosis to improve regardless of the treatment regimen. Unfortunately, the degenerative changes of the IVD's, vertebral bodies, and associated diarthrodial joints are permanent and, in most cases, progressive. Treatment is therefore aimed at reducing symptoms and future attacks by proper case management and prophylaxis. Exacerbation of symptoms is quite common, and months or years may elapse between attacks. With age and the gradual increase in degenerative changes, attacks are more closely spaced, and recovery from each attack is prolonged. Any trauma superimposed on silent cervical spondylosis can result in permanent partial disability of the cervical spine with symptoms far out of proportion to the severity of the injury.

In cervical myelopathy, there is a gradual increase in the neurologic signs and symptoms until a leveling off occurs and symptoms remain stationary, unless superimposed trauma ensues. Although conservative care does produce remission of subjective symptoms, especially in early diagnosed cases, objective signs are rarely changed and sensory symptoms often return and progress to a plateau. Thus, suggests Whiting, surgical intervention is probably the treatment of choice in myelopathy once symptoms return following a trial of conservative care, especially if there is evidence of paralysis.


Cervical Scoliosis

When viewed from the back, the vertical lateral line of gravity passes through the occipital protuberance and the vertebrae's spinous processes. In cervical scoliosis, the midcervical spinous processes will especially tend to deviate laterally from this line.

      BACKGROUND

Cervical scoliosis is often mechanically predisposed by flattening rather than exaggeration of the cervical lordosis. This is quite common during youth. As mentioned previously, the posterior joints become relatively lax during flattening of the cervical spine. This encourages retropositioning and posterior subluxations that are frequently the first step toward cervical scoliosis.

In the common rotary cervical scoliosis, the spinous processes tend to rotate toward the convex side of the lateral curve, the vertebral bodies rotate toward the concave side, and the discs and articular facets become subjected to abnormal stretching forces as they open on the side of convexity and compressive forces on the side of concavity. This type of cervical scoliosis is usually the compensatory effect of a lower scoliosis to the other side and a common cause of recurring episodes of nontraumatic torticollis.

      BIOMECHANICS

It is important here to review how normal discs react to asymmetrical forces. When a cervical disc is loaded unilaterally, the disc initially becomes wedge-shaped and the normally parallel vertebral plateaus form an angle. This vertically stretches the anular fibers that are opposite the weight-bearing side, but this action is quickly counteracted by forces transmitted laterally from the resilient nucleus to help the disc return to its normal shape. This self-stabilization factor is the product of a healthy nucleus and anulus working as a mechanical couple.

In cervical scoliosis, there are also disc reactions to rotary forces that must be considered. As the apposing layers of anular fibers run alternately oblique in opposite directions, the oblique disc fibers angled toward the direction of twist become stretched when a vertebra rotates, and the oblique fibers running against the direction of rotation tend to relax. The greatest tension from stretch is seen centrally where the fibers are nearly horizontal. This increases nuclear pressure by compression in proportion to the amount of rotation. If severe, the nucleus can be dislodged from its central position.

Cervical scoliotic rotation is also associated with a lateral tilt that increases the distance between the lateral margins of the vertebral bodies on the convex side of the curve. This stretches the lateral anulus which produces a contraction of that part of the disc and a compensatory bulging of its contralateral (thinned) aspect. If the anular filaments become stretched, weakened, and the disc loses some of its stiffness property, the nucleus may shift from its central position so that the vertebral segment is unable to return to its normal position. A firmly locked rotational subluxation can result.

Thus, vertebral tilting as seen in subluxations with disc wedging alters the relationship of apposing articular surfaces to produce a change in the direction of compressive forces on these joints and the nucleus of the disc. In addition to tilting, severe rotation produces abnormal jamming compression forces on ipsilateral facets and stretching tension forces on contralateral opened facets.

When continuous compression is applied to any active and mobile joint, cartilaginous erosion followed by arthritis can be expected. When continuous stretching is applied to any active and mobile synovial joint, capsulitis can be expected.

When scoliotic rotation takes place evenly among the cervical segments and the cervical nuclei hold their relatively central position in the discs, the situation is usually asymptomatic even though erosion and arthritis can be demonstrated on roentgenographs. However, if a nucleus fails to hold its central position and shifts laterally away from the point of maximum compression, the superimposed vertebra will be encouraged to present a fixed clinical subluxation.


Torticollis

Regardless of the cause of torticollis, the neck is rigid and tender, the head tilts laterally toward the side of spasticity, and the chin is usually rotated to the contralateral side. Care must be taken to determine the etiology and differentiate its many possible causes.

      BACKGROUND

Besides traumatic causes, torticollis may have an inflammatory, a congenital, or a neuropathic origin, or be of various superimposed factors.

Severe Trauma.   Traumatic dislocations of upper cervical vertebrae cause a distortion of the neck much like that of torticollis. A rotary fracture-dislocation of a cervical vertebra, especially of the atlas on the axis or the axis on C3, will produce neck rigidity and a fast pulse, but fever is absent. Local and remote trigger points are frequently involved. Even in mildly suspicious cases, the neck should always be x-rayed in two or more planes before it is physically examined.

Inflammation.   "Wry neck" spasm (tonic, rarely clonic) of the sternocleidomastoideus and trapezius may be due to irritation of the spinal accessory nerve or other cervical nerves by swollen glands, abscess, acute upper respiratory infections, scar, or tumor. A spontaneous subluxation of the atlas may follow severe throat infection (eg, pharyngitis). Neck rigidity may also be the result of a sterile meningitis from blood in the cerebrospinal fluid. Thus, if a patient has slight fever, rapid pulse, and rigid neck muscles, subarachnoid hemorrhage should be suspected. Lateralizing signs are often indefinite.

Congenital, Neuropathic, and Idiopathic Forms.   The congenital form is commonly associated with Klippel–Feil syndrome, atlanto-occipital fusion, and pterygium colli. Focal neuropathic causes include ocular dysfunctions, syringomyelia, and tumors of the spinal cord or brain. Idiopathic forms are seen in acute calcification of a cervical disc, rheumatic arthritis, tuberculosis, or "nervous" individuals. Nelson feels that wry neck may also be the result of subdiaphragmatic or subclinical visceral irritation being mediated reflexly into the trapezius and cervical muscles.

Maigne's Test.   The examiner places a seated patient's head in extension and rotation. This position is held for about 15–40 seconds on each side. A positive sign is indicated by nystagmus or symptoms of vertebrobasilar ischemia.

DeKleyn's Test.   The patient is placed supine on an adjusting table, and the head rest is lowered. The examiner extends and rotates the patient's head, and this position is held for about 15–40 seconds on each side. A positive sign is the same as that seen in Maigne's test.

Hautant's Test.   The examiner places a seated patient's upper limbs so that they are abducted forward with the palms turned upward. The patient is instructed to close his eyes, and the examiner extends and rotates the patient's head. This position is held for about 15–40 seconds on each side. A positive sign is seen when one or both arms drop into a pronated position, suggesting a vertebrobasilar disorder.

Underburger's Test.   The patient is asked to stand with his upper limbs outstretched, his eyes closed, and then to march in place with his head extended and rotated. The examiner should stand close to the patient during the test because a positive sign is a loss of balance. If this should happen, a vertebrobasilar disorder should be suspected.

Subluxation.   The most common direct cause is that from irritating cervical subluxation (eg, trauma, rotational overstress, unilateral chilling, unilateral lifting, instability). Subluxation may also be an asymptomatic complicating factor to those etiologic factors mentioned above.

Barge states that the structural cause of torticollis is a rotatory vertebral malposition and abnormal disc wedging, where the nucleus of an involved disc has been forced to shift away from compressive forces. The patient's symptoms are often self-limiting with time and rest that allows the disc to expand in its nonweightbearing (decompressed) state and the vertebral facets to be relieved of their jammed position. It can be theorized, however, that if the neck does not achieve this subluxation correction through disc imbibition a rotatory scoliosis is produced in adaptation so that the victim may at least have a straight eye level. But, as the now chronic subluxation has not been fully corrected, it can serve as a focus for morbid neurologic and degenerative processes, especially at the zygapophyses, covertebral joints, and IVF's.

The pain associated with acute torticollis is thought to be attributed essentially to zygapophyseal capsulitis and covertebral joint inflammation. This can generally be confirmed by palpation and should not be confused with the pain of stretching the rigid muscles on the side of the concavity.

      APPLIED ANATOMY

In the healthy cervical (or lumbar) spine that presents a moderate degree of lordosis, a good share of weight bearing is upon the zygapophyses because the line of cumulative loading of compressive forces is quite posterior to the center of the vertebral bodies. This produces a considerable degree of normal articular jamming as the result of loading that tends to restrict excessive rotation. That is, the rotary motion that occurs at the zygapophyses does so upon relatively compressed facets.

There is structural adaptation for this. For the normal adult spine, the cervical discs average 3 mm in thickness, there is a 2:5 disc/body ratio, a 4:7 nucleus/anulus ratio, and the nucleus sits in a position that is slightly posterior to the center of the disc. In addition, the surface area of the cervical facets is larger in proportion to the surface area of the vertebral body than at any other region of the spine. This contributes greatly to the overall segmental base of support in the neck. In fact, the weight-bearing surfaces of the two facets equal more than half (67%) that of the centrum. In addition, the superior facets below the axis face posterosuperior and medial to compensate for the normal anteroinferior tilt of the vertebral bodies.

The more the cervical curve becomes flattened, the more superimposed weight is shifted to the discs. With the shifting of the normal compressive force at the posterior toward the anterior of the motion unit, the discs are forced to carry more weight and a greater responsibility in cervical stability. In time, this unusual compressive force on the nucleus can produce degenerative anular thinning, spurs, ebernation, and Schmorl's nodes. The posterior joints become relatively lax and predispose retropositioning and posterior subluxations.

      CLINICAL CLASSIFICATIONS

Following is a classification, based on Barge's findings, of three major types of torticollis that are the result of disc lesions.

Type I: Lateral Torticollis.   The patient's neck is rigidly flexed laterally and locked, and usually accompanied by a degree of rotation of the chin away from the side of tilt. The spinous process of the involved vertebra will often palpate as being distinctly lateral as compared to its neighbor above and below.

From either traumatic or degenerative causes, the stiffness property of anular filaments may be so weakened as to allow considerable nuclear shifting within the disc. Barge feels that lateral shifting of the firm nucleus and consequent inferior tilting of the superimposed vertebra as it falls on a weakened anulus is the primary cause of lateral torticollis. Thus, a lateral nuclear shift to one side would be accompanied by disc compression on the other side, and the vertebral body above would tend to rotate away from the relatively higher side of the disc (nuclear site), following the plane of its base of support. It should be remembered that the nucleus serves as a ball-bearing-like fulcrum of movement of the superimposed vertebra.

The lateral tipping of the centrum causes the inferior apophyseal facet of the vertebra to ride down on the side of the thinned disc and up on the side to which the nucleus has shifted. This is usually within the range of physiologic movement. However, the added rotation of the centrum causes the inferior facet of the vertebra to separate (open) on the side of rotation, stretching the apophyseal capsule and covertebral synovial tissues beyond their normal limit, while the inferior facet on the other side merely rides up and serves as a pivot point for subluxation. This would encourage apophyseal capsulitis and covertebral inflammation, with profound reflex spasm to splint the affected area locked by the displaced nucleus.


Type II: Anterior Torticollis.   The subject's cervical area is rigidly projected forward. In severe cases, all cervical motions are restricted. In mild cases, the complaint may be only a "stiff neck."

It should be kept in mind that the relatively small atlas must provide an upward push equal to the weight of the head. This is about a 14–lb static resistance force for a 200–lb individual. If the head is tilted so that its center of mass is not in line with both atlantal articulations, the cervical muscles opposite to the direction of tilt must contract to maintain equilibrium. If the muscles and ligaments at the base of the skull do not check the compressive and shear forces, failure can readily produce a degree of subluxation.

Using the same reasoning as given for lateral torticollis, anterior torticollis is predisposed by a flattened area in the cervical spine that allows laxity of the zygapophyseal check ligaments, a posterior shifting of a nucleus, posterior disc bulge, and anteroinferior displacement of the superimposed vertebra (following the plane of its base of support) as its inferior facets ride up the superior facets of the subjacent vertebra. The spinous process can frequently be palpated as being distinctly superior.

As the inferior facets of the involved vertebra tip anteroinferior on the superior facets below, a pivot action occurs that overstretches the apophyseal capsules posteriorly. If severe, this will produce an apophyseal capsulitis and local tenderness will be acute. If the atlas has displaced anteriorly on the axis, a capsulitis may also occur at the atlantal-dens articulation and/or less frequently at the dens-cruciate junction.


Type III. Anterolateral Torticollis.   This form of torticollis, the most frequently seen type, presents a combined lateral and anterior torticollis subluxation. The patient's neck is grossly projected forward and to one side, and the symptoms are usually intense. The disc mechanism involved is the same as that for lateral and anterior torticollis except that the involved nucleus is thought to shift obliquely in a posterolateral direction.

The above described types of torticollis are merely points of study. Within a clinical case, any type may occur singularly or in combination and may involve one or more segments. If only one vertebra within an area is essentially involved, a nuclear shift should be suspected after fracture and dislocation have been ruled out. Barge also explains contralateral attacks as being the result of a horizontal shifting of a nucleus from one side to the other.

In chronic cases, the patient may be asymptomatic if the sites of acute inflammation have become fibrotic. Most of the symptoms presented will usually be neurologic or vascular in nature such as the paresthesiae and referred pain of brachial plexus syndromes.

      SELECTED EFFECTS OF CERVICAL AREA HYPERTONICITY

Excessive hypertonicity of a muscle, confirmed by palpatory tone and soreness, will tend to subluxate its site of osseous attachment. Below is a listing of common problem areas in the neck.

1. Splenius capitis.   Increased tone tends to pull the C5–T3 spinous processes lateral, superior, and anterior and to subluxate the occiput inferior, medial, and posterior.
   
   

2. Scalenus anterior.   Hypertonicity tends to pull the C3–C6 transverse processes inferior, lateral, and anterior and the 1st rib superior and medial.
   
   

3. Scalenus medius.   Excessive tone tends to pull the C1–C7 transverse processes inferior, lateral, and anterior and the 1st rib superior and medial.
   
   

4. Scalenus posterior.   Hypertonicity tends to pull the C4–C6 transverse processes inferior, lateral, and anterior and the 2nd rib superior and medial.
   
   

5. Obliquus capitis superior.   Increased tone tends to roll the occiput anterior and inferior and pull the atlas posterior and superior to produce a lateral occiput tilt and condyle jamming.
   
   

6. Obliquus capitis inferior.   Increased tone tends to produce a rotary torque of the atlas-axis motion unit.
   
   

7. Rectus capitis posterior major.   Hypertonicity tends to pull the occiput posterior, inferior, and medial and the spinous of the axis superior, lateral, and anterior. Strong hypertonicity will lock the occiput and axis together so that they appear to act as one unit even though they are not contiguous.
   
   

8. Interspinales.   Excessive muscle tone between the spinous processes tends to hyperextend the motion unit.
   
   

9. Sternocleidomastoideus.   Increased tone tends to pull the sternum and clavicle posterior and superior and the occiput inferior and anterior.
   
   

10. Upper trapezius.   Hypertonicity tends to pull the occiput posteroinferior, the C7–T5 spinous processes lateral, and the shoulder girdle medial and superior.

The Troublesome Fifth Cervical Area

In the previous discussion on cervical fixation, it was pointed out that the multifidi are especially prone to fixation at the C4–C6 area. In the discussion on cervical disc disorders, it was stated that the encroachment of space, faulty movement, apophyseal subluxation, osteophyte formation, and disc degeneration and protrusion occurs most frequently at the C4–C6 level. It was also stated that the highest incidence of cervical spondylosis is found at the C4–C6 level. This is also true for early osteoarthritis in the neck, IVD narrowing, apophyseal compression fracture, dislocation pivot point, traumatic brachial traction, extension whiplash injury, lower cervical fixation, a dislodged disc nucleus, and ankylosing spondylitis. A common trigger point in "stiff neck" is found in the splenius cervicus, lateral to the C4–C6 spinous processes. These facts were derived from the research of a large number of separate researchers with various backgrounds (chiropractic, allopathic, osteopathic, bioengineering).

The clinical importance of the 5th cervical vertebra was brought out by pioneer chiropractor Clarence Reaver in the 1930's, and it has been emphasized recently by Pierce. The biomechanical importance of the C5 vertebra becomes logical when we realize that the cervical curve often extends from C1 to T2, with its apex at C5. It is not functionally restricted to the C1–C7 vertebrae as depicted in most anatomy textbooks, where the classic apex of the lordosis is located at C4.

Range of Motion.   In the previous chapter, it was mentioned that normal spinal motion in the pure horizontal plane occurs only at the center of the curves (Fig. 6.9). While 50% of A–P motion of the cervical spine takes place between the occiput and the atlas, the remainder is distributed among the other cervical vertebrae with C5 and C6 making the greatest contribution. This is also true in lateral bending and rotation below the axis. Thus, if C5 becomes fixed, compensatory effects (and symptoms) will be exhibited at the upper cervical and upper dorsal areas. This is readily confirmed empirically. In abnormal cervical kyphosis, it will be found that C5 is most frequently the center vertebra of the affected segmental region and symptomatic picture.

Neurology.   We note in practice that upper extremity symptoms are far more frequently exhibited on the lateral (radial) aspect of the shoulder and arm than on the medial (ulnar) aspect. Abduction weakness of the shoulder is much more common than adduction weakness. A causative hypothesis is that this occurs because the C5 and C6 nerves comprise the upper aspect of the brachial plexus, supplying fibers to the musculocutaneous, axillary, radial, and median nerves – all but the ulnar. The deltoid muscle is innervated almost entirely by the C5 nerve. The biceps muscle receives dual innervation from the C5 and C6 nerves. Thus the strength of the deltoid and biceps are excellent sources to determine the motor integrity of midcervical innervation. It should also be noted that the C5 afferent pathway supplies sensation from the lateral arm, especially that over the deltoid –the site of the common "silver dollar sign" of hypesthesia. Another important test is the biceps reflex, essentially determined by the C5 pathway with a lesser C6 component. Cervical compression tests usually stress the C5 segment more than any other area because of its horizontal plane.

Rheumatic Disease of the Cervical Spine

This common and highly deforming disorder is a generalized disease of connective tissue that initiates in joint synovium. Even when cervical symptoms are absent, periodic cervical roentgenographs should be taken to assess progress.

The initial target areas in the cervical spine are the apophyseal joints and the synovial tissues anterior and posterior to the dens where it articulates with the anterior arch of the atlas and the cruciate ligament. Other tissues affected include the IVD's, spinal ligaments, and extradural alveolar tissue. A genetic susceptibility factor has been shown to be involved in most cases.

The length of the cervical cord and cervical discs is greatest during flexion and least during extension in the normal spine. The opposite is true in the rheumatic spine due to loss of disc and vertebral body height from destruction and absorption.

      RHEUMATIC ATLANTOAXIAL SUBLUXATION

Orthopedic subluxation is always a danger, proceeding from the synovitis, apophyseal erosion, and erosion of the vertebral bodies involved which lead to instability from joint destruction and ligamentous laxity. As apophyseal erosion progresses, the dens migrates into the foramen magnum and the atlas becomes fixed to the axis to reduce the possibility of dislocation. These signs determine the severity and prognosis of the general disease.

The characteristic anterior subluxation of the atlas on the axis is generally considered to be an adaptation change to help increase the capacity of the spinal canal as rheumatoid tissue accumulates. If this is true, the decision for clinical reduction presents a dilemma. This anterior subluxation usually occurs only in flexion unless granulation tissue between the atlas and dens prevents reduction during extension. Thus, direct reduction of the orthopedic rheumatic subluxation by either manipulation or traction is usually contraindicated. Jeffreys states: "The incidence of neurological damage in subluxated (rheumatic) spines is very low" and "not infrequently the cord only becomes compromised when the subluxation is reduced."

      NEUROLOGIC DAMAGE

Nerve roots may become entrapped within one or more IVF's from a combination of subluxation, perivascular adhesions, dural adhesions, rheumatoid nodules, granulation tissue, and sequestrated disc tissue. Neck pain, with or without radiation to the arms, weakness, feelings of instability, ataxia, and paresthesiae are common symptoms. However, these cervical symptoms are difficult to differentiate if the disease initiates in the peripheral joints where signs of peripheral entrapment, myositis, tenosynovitis, and subluxated joints from tendon rupture exist. Related giddiness and fainting spells suggest an associated vertebral artery ischemia that is usually associated with the upward migration of the dens producing a kinking of the vertebral artery at the atlas level.

      DIFFERENTIATION FROM SPONDYLOSIS

In both degenerative and rheumatic spondylosis, involvement of the cervical cord first involves the anterolateral tracts and central gray matter of the cord. The effect is signs of an upper motor (pressure ischemia) lesion with a degree of tetraparesis produced by the reduced A–P dimension of the vertebral canal.

Degenerative spondylosis is differentiated from rheumatoid spondylosis in that the later frequently involves the upper cervical area and osteophyte formation and end-plate sclerosis are usually absent, unless the two disorders are superimposed. The small peripheral joints are usually also involved in rheumatoid arthritis.


Ankylosing Spondylitis of the Cervical Spine

In ankylosing spondylitis, the tissues subjacent to articular cartilage are the first to be affected. Thus, the cartilage is invaded and erodes from below as contrasted to the surface erosion of rheumatoid arthritis.

Early diagnosis and management is important to reduce gross deformity. The first signs are not usually cervical but found in the dorsal spine (reduced chest expansion), lumbar spine (vertebral body "squaring"), and sacroiliac joints (erosion). The first cervical sign is usually that of reduced lateral flexion, followed by increasing gross neck flexion at rest and upper cervical subluxation. However, deformity is usually greatest at the lumbar spine and hips.

In addition to the disease process itself, a great danger in the ankylosing spine is the addition of trauma. Because the neck is unable to properly extend, any anteriorly directed force to the head can easily inflict a vertebral fracture. This usually occurs through a fused disc area, with or without residual displacement. Regardless, instability is great. Cord damage can result from impact if the shear forces produce posterior displacement.


Cervical Deformities and Anomalies

Congenital deformities of the cervical spine are extremely frequent but not frequently extreme. Those that have biomechanical significance vary in severity from minor to severe and occur multiply or singly. The cause is purely genetic transmission in about 35% of cases, and the remainder is due to environmental factors or a mixture of genetic and environmental factors.

Gross anomalies are rarely seen in chiropractic practice unless well adapted to the individual's life-style. However, subtle and asymptomatic anomalies in the cervical area frequently predispose subluxations from minor stress and underlie a pathologic process. Many anomalies do not become symptomatic unless the effects of trauma or degeneration are added. The primary concerns are whether the deformity will increase with growth and normal activity and how much does the deformity contribute to the degree of cervical instability and neurologic deficit present.

      BONY ANOMALIES OF THE CERVICAL SPINE

Three general classifications can be made:

   1.  Cranio-occipital anomalies
          a. Basilar coarction.
          b. Occipital vertebrae
          c. Atlantoid assimilation.
          d. Occipital dysplasia
          e. Condylar hypoplasia.

   2.  Anomalies of the atlas and axis
          a. Atlas arch dysplasia
          b. Odontoid dysplasia.

   3.  Lower cervical anomalies (C3–C7)
          a. Failure of segmentation (eg, Klippel-Feil syndrome)
          b. Fusion failure (eg, spina bifida, spondylolisthesis)
          c. Cervical rib.

The above deformities are described in detail in standard radiologic atlases and do not require repetition here. However, a few points are worthy of review in this section.

      CRANIOVERTEBRAL MALFORMATIONS

These many and varied anomalies arise from occipital malformations characterized by an abnormal shift upward of the atlas and axis with the odontoid protruding above Chamberlain's line (Fig. 7.69). Such anomalies are frequently associated with congenital neural malformations and with other osseous deformities (eg, Klippel-Feil syndrome). As these anomalies may remain asymptomatic unless precipitated by compressive forces following trauma or of degeneration, a concern is that these anomalies may easily be confused with the root/cord signs and symptoms of lower cervical spondylosis. Headache, sensory loss, limb pain, and ataxia are often associated.

Congenital Basilar Coarctation and Platybasia.   Basilar coarctation is the state where the tip of the odontoid lies abnormally high above Chamberlain's or McGregor's line. The disorder should not be confused with platybasia, an anthropometric flattening of the base of the skull as seen in Down's syndrome. This is often associated with congenital atlantoaxial subluxation, which occurs in 20% of mongoloid children. Platybasia is measured by the angle extending from the clivus and the episthion that is greater than 130°. Such development deformity must be differentiated from basilar impression.

Basilar Impression.   This rare deformity is the result of a congenital or an acquired invagination of the odontoid process into the foramen magnum, measured by the height of the odontoid above Chamberlain's or McGregor's line on a lateral film. The diagnostic A–P line of Fischgold-Metzger is used to differentiate basilar impression from an abnormally long dens and/or high palate (Fig. 7.70). In basilar impression, the atlas appears to indent the base of the skull on an A–P film as the odontoid approaches the brain stem. During inspection, the ears will be closer to the shoulders even though the length of the cervical spine is normal. The congenital form is usually associated with other defects such as atlanto-occipital fusion, aplasia of the posterior arch of the atlas, and atlantoaxial dislocation. The acquired form is a sign seen in Paget's disease and osteomalacia or rickets. It is the result of head weight superimposed on softened structures at the base of the skull. Often, symptoms do not appear until later life and then can mimic a number of acquired neurologic disturbances.

Occipitalization.   Atlanto-occipital fusion (atlantal assimilation) is the most common anomaly of this joint, and C2–C3 fusion is associated in 70% of the cases. The gross features are those of Klippel-Feil syndrome.

Aplasia of the Arch of the Atlas.   This rare deformity may vary from a slight opening to a complete loss of the anterior arch. Quite often the anomaly is asymptomatic unless precipitated by trauma.

Odontoid Anomalies.   These rare deformities vary from an abnormally small size (hypoplasia) to a bifid odontoid, os odontoideum (suggesting congenital dysplasia or traumatic nonunion), or complete absence (agenesis). It is easy to confuse congenital absence to that of absorbed nonunion after fracture in early life.

Congenital Atlantoaxial Instability.   Various precipitating factors may be involved in congenital predisposition to atlantoaxial instability. Most common are an abnormal odontoid, a loose cruciate ligament, and atlanto-occipital fusion –all of which can produce transient narrowing of the spinal canal and compression of its contents. The normal anterior atlas-dens interval is 3 mm in the adult and 4 mm in the child, particularly during flexion (Fig. 7.71). A distance greater than this indicates a ruptured or stretched transverse cruciate ligament following acute trauma. It should be kept in mind that a hypermobile odontoid is also seen in mongoloids and rheumatoid arthritis. Of equal importance is the corresponding posterior dens-atlas interval that indicates the space available for the tissues within the spinal canal. It is rare to find an adult patient with less than 19 mm of posterior dens-atlas space who is asymptomatic, and cord compression is possible when the space is less than 17 mm.

      CONGENITAL TORTICOLLIS

The clinical picture of this deformity is one of contracture of the sternocleidomastoidius, where the head tilts toward the involved side and the chin rotates towards the contralateral side. A related facial deformity is often exhibited in later life.

Coventry/Harris have reported that 90% of their infant patients respond to stretching exercises alone, yet undoubtedly a degree of subluxation exists (usually C1–C2) that should be corrected. The birth history will often portray a forceps delivery.

In skeletal torticollis, compensatory scoliosis below the defect may hide the physical picture or asymmetry of the occipital condyles that cause tilting of the atlanto-occipital and atlantoaxial joints. Exclusion must be made from acquired muscular torticollis.

      KLIPPEL-FEIL SYNDROME

This syndrome, which varies in degree of severity, classically consists of a short neck, a low hair line, and severe neck stiffness associated with fusion of the cervical (and possibly upper thoracic) vertebrae into bony blocks. It is sometimes referred to as congenital cervical synostosis. A case may be structurally severe yet asymptomatic of neurologic signs (eg, paresthesia, mirror movements of hands from an underlying neural defect) unless precipitated by trauma. Idiopathic deafness occurs in 30% of cases.

Associated deformities frequently include degrees of scoliosis and kyphosis; hemivertebrae; cervical rib; spina bifida; Sprengel's deformity, which is a small, elevated scapula often connected to the cervical spine; and Turner's syndrome, featuring webbing of the neck, gonadal hypoplasia, and cubitus valgus.

Acquired fusions are differentiated by the facts that:

(1) in acquired fusions, the margins of the vertebral body tend to be irregular, disc lines are wider than the adjacent vertebral bodies, the posterior arches are frequently subluxated,

(2) congenital fusions are narrow, the disc remnants are no wider than the adjacent bodies, bony trabeculae tend to cross the disc line, and

(3) associated deformities are not found.

      CONGENITAL SPINAL STENOSIS

A degree of congenital narrowing of the cervical vertebral canal, for some reason seen only in males, will easily mimic cervical spondylosis in the young. Progressive thickening of the laminae is often initially diagnosed as multiple sclerosis due to the progressive tetraplegic spasticity produced.

      CERVICAL RIB

Anomalous development of extra ribs in the region of the cervical vertebrae may be a single unilateral rib, bilateral, or multiple bilaterally. The condition is usually seen at C7, but may arise as high as C4, and the cause is a variation in the position of the limb buds. The anomaly may vary from a small nubbin to a fully developed rib. A small rudimentary rib may give rise to more symptoms than a well-developed rib because of a fibrous band attached between the cervical rib and sternum or 1st thoracic rib.

Significance.   A cervical rib arising from C7 and ending free or attached to the T1 rib appears in the neck as an angular fullness which may pulsate owing to the presence of the subclavian artery above it. It rarely produces symptoms, and it is often first noticed when percussing the apex of the lung. The bone can be felt behind the artery by careful palpation in the supraclavicular fossa and demonstrated by roentgenography. Pain or wasting in the arm and occasionally thrombosis may occur from impaired circulation.

Grieve points out that some clinicians are far too anxious to blame upper limb paresthesiae on the presence of a cervical rib just because it is there. Many patients with a cervical rib have no complaints, many without a cervical rib have similar complaints, and many patients with complaints have symptoms on the contralateral side of a unilateral cervical rib. However, when any anomaly such as a cervical rib is seen roentgenographically, the examiner should be suspicious that other anomalies not as evident may be associated.

Differential Considerations.   The etiologic theories of the cervicobrachial syndrome are compression of the nerve trunks, trauma to nerve trunks, injuries to the sympathetic and vasomotor nerves, trauma to the scalenus anterior muscle, embryologic defects, postural or functional defects, narrowing of the upper thoracic cap as a result of adjacent infections or anatomic defects, acute infection producing myositis, intermittent trauma to the subclavian artery, or a cervical rib.

Case Management.   Palliative relief can be obtained in many cases by correction of posture and specific subluxations, gentle manipulation of the upper dorsal and lower cervical spine, cervical traction and other relaxing physiotherapy. Those cases treated conservatively usually show a recurrence of symptoms periodically, and those cases that do not respond to conservative treatment frequently require surgery.