Neuroconceptual Models of Chiropractic
Chapter 5 from: Basic Principles of Chiropractic Neuroscience
By Richard C. Schafer, D.C., FICC and the ACAPress
The structural spinal fault, the associated nerve involvement, and the ensuing functional alterations comprise classic chiropractic subluxation concepts. In contrast, limited concepts of spinal biomechanical faults, modes of possible nerve involvement, and etiologic rationales of functional changes promote narrow viewpoints, disciplines, and therapeutic approaches, as well as foster empiricism and dogma. Awareness of the varied concepts of structural lesions, neuroinsults, and the causes of abnormal functional changes promotes wider perspective for intuitive practices, multifaceted observations, and fewer practices with reliance on empiricism that is dictated by dogmatic frameworks.
What is Different About Spinal Pain?
Chiropractic & Manual Therapies 2012 (Jul 5); 20 (1): 22 ~ FULL TEXT
This thesis addressed the question "what is different about spine pain?" Neuroanatomic and neurophysiologic findings from studies in the last twenty years provide preliminary support for the thesis that deep spine pain is different from deep pain arising from peripheral limb structures.
Cerebral Perfusion in Patients with Chronic Neck
and Upper Back Pain: Preliminary Observations
J Manipulative Physiol Ther. 2012 (Feb); 35 (2): 76–85
RESULTS: Group 1 (mild) consisted of 14 patients. Cerebral perfusion measured by SPECT was normal in all 8 brain regions. Group 2 (moderate) consisted of 16 patients. In this group, a decrease in cerebral perfusion was observed (range, 20%-35%), predominantly in the parietal and frontal zones. Group 3 (severe) consisted of 15 patients. In this group, the decrease in cerebral perfusion observed was from 30% to 45%, again predominantly in the parietal and frontal zones. A significant difference was found between NDI groups ("moderate" and "severe" showed significantly greater hypoperfusion than "mild"). Total blockage score correlated with SPECT scores at r = 0.47, P = .001. In a multivariate analysis, NDI scores contributed 39% of the variance of SPECT scores.
Cerebral Metabolic Changes in Men
After Chiropractic Spinal Manipulation for Neck Pain
Altern Ther Health Med. 2011 (Nov); 17 (6): 12–17
Research on chiropractic spinal manipulation (CSM) has been conducted extensively worldwide, and its efficacy on musculoskeletal symptoms has been well documented. Previous studies have documented potential relationships between spinal dysfunction and the autonomic nervous system and that chiropractic treatment affects the autonomic nervous system. The authors hypothesized that CSM might induce metabolic changes in brain regions associated with autonomic nervous system functions as assessed with positron emission tomography (PET). PET is a nuclear medicine imaging technique that allows quantification of cellular and molecular processes in humans such as cerebral glucose metabolism which is thought to reflect regional neuronal activities.
Spinal Motor Neuronal Degeneration After Knee Joint
Immobilization in the Guinea Pig
J Manipulative Physiol Ther. 2010 (Jun); 33 (5): 328–337
After various periods of knee joint immobilization, a variety of features of motor neuronal degeneration were observed. Specific characteristics included gradual increases in the expressions of neuronal nitric oxide synthase and ultrastructural changes in affected motor neurons including reduction of cell organelles, indentation of the nuclear envelop, and small compact clumps of chromatin in the nuclei. We conclude that motor neuronal degeneration in the spinal cord and axons in this study was the result of knee joint immobilization. Increases in motor neuronal nitric oxide-mediated oxidative stress level after reduction of target tissue activity may contribute to the mechanism for degenerative changes in the motor neurons in adult spinal cord of the guinea pig.
Exploring the Neuromodulatory Effects of the Vertebral Subluxation
and Chiropractic Care
Chiropractic Journal of Australia 2010 (Mar); 40 (1): 37–44 ~ FULL TEXT
Over the past 15 years our research group has been conducting a variety of experiments aimed at testing out the theory that adjusting subluxations improves central nervous system functioning and overall expression of health and well being. To do this the theory was first formulated into a model (Figure 2) that could be scientifically tested with a programme of research studies. This model became the basis for the lead author’s PhD research,  and continues to be a foundational premise that our research group is attempting to elucidate with our work. The model was constructed using early chiropractic research data and a thorough review of the neurophysiology scientific literature.
Immobilization Induces Changes in Presynaptic Control
of Group Ia Afferents in Healthy Humans
J Physiol. 2008 (Sep 1); 586 (Pt 17): 4121–4135
Although the present study involved limb immobilization in able-bodied subjects, the findings may also be of clinical relevance. This is especially the case in relation to neurological disorders leading to physical inactivity. It is noteworthy that the findings of increased H-reflexes, decreased GABAergic presynaptic inhibition and decreased post-activation depression following immobilization to some extent matches the findings of previous studies in spastic patients and it is worth considering the effects of reduced physical activity in itself. As mentioned previously, it is possible that the decreased presynaptic inhibition and post-activation depression observed in patients with cerebral or spinal lesions may at least in part be a consequence of the disuse of motoneurons and Ia afferents.
Preliminary Morphological Evidence That Vertebral Hypomobility
Induces Synaptic Plasticity in the Spinal Cord
J Manipulative Physiol Ther. 2007 (Jun); 30 (5): 336–342
These preliminary data suggest that chronic vertebral hypomobility (fixation) at L4 through L6 in the rat affects synaptic density and morphology in the superficial dorsal horn of the L2 spinal cord level. Morphological parameters that appear to be affected include synaptic curvature, type of postsynaptic profile, and perforations of the PSD. Additional more definitive studies are warranted, and the biologic significance of these finding should be investigated.
Does Facet Joint Inflammation Induce Radiculopathy? An Investigation
Using a Rat Model of Lumbar Facet Joint Inflammation
Spine (Phila Pa 1976) 2007 (Feb 15); 32 (4): 406–412
The association between lumbar facet joint inflammation and radiculopathy was investigated using behavioral, histologic, and immunohistochemical testing in rats. Both mechanical and chemical factors have been identified as important for inducing radiculopathy. In lumbar spondylosis, facet joint osteophytes may contribute to nerve root compression, which may induce radiculopathy. Furthermore, inflammation may occur in the facet joint, as in other synovial joints. Inflamed synovium may thus release inflammatory cytokines and induce nerve root injury with subsequent radiculopathy. (In this study) when inflammation was induced in a facet joint, inflammatory reactions spread to nerve roots, and leg symptoms were induced by chemical factors. This work supports yet another aspect of the Vertebral Subluxation Complex hypothesis.
Biomechanical and Neurophysiological Responses to Spinal Manipulation
in Patients With Lumbar Radiculopathy
J Manipulative Physiol Ther. 2004 (Jan); 27 (1): 1–15
Because spinal manipulation (SM) is a mechanical intervention, it is inherently logical to assume that its mechanisms of therapeutic benefit may lie in the mechanical properties of the applied force (mechanical mechanisms), the body's response to such force (mechanical or physiologic mechanisms), or a combination of these and other factors. Basic science research, including biomechanical and neurophysiological investigations of the body's response to SM, therefore, should assist researchers, educators, and clinicians to understand the mechanisms of SM, to more fully develop SM techniques, to better train clinicians, and ultimately attempt to minimize risks while achieving better results with patients.
Joint Manipulation Reduces Hyperalgesia By Activation of Monoamine Receptors
But Not Opioid or GABA Receptors in the Spinal Cord
Pain. 2003 (Nov); 106 (1-2): 159–168 ~ FULL TEXT
Joint manipulation has long been used for pain relief. However, the underlying mechanisms for manipulation-related pain relief remain largely unexplored. The purpose of the current study was to determine which spinal neurotransmitter receptors mediate manipulation-induced antihyperalgesia. Rats were injected with capsaicin (50 microl, 0.2%) into one ankle joint and mechanical withdrawal threshold measured before and after injection. The mechanical withdrawal threshold decreases 2 h after capsaicin injection.
Neuromechanical Characterization Of In Vivo Lumbar Spinal Manipulation.
Part II. Neurophysiological Response
J Manipulative Physiol Ther. 2003 (Nov); 26 (9): 579–591
Spinal manipulative thrusts resulted in positive electromyographic (EMG) and compound action potential (CAP) responses that were typically characterized by a single voltage potential change lasting several milliseconds in duration. However, multiple EMG and CAP discharges were observed in numerous cases. The temporal relationship between the initiation of the mechanical thrust and the neurophysiologic response to internal and external spinal manipulative therapy (SMT) thrusts ranged from 2.4 to 18.1 ms and 2.4 to 28.6 ms for EMG and CAP responses, respectively. Neurophysiologic responses varied substantially between patients. Vertebral motions and resulting spinal nerve root and neuromuscular reflex responses appear to be temporally related to the applied force during SMT. These findings suggest that intersegmental motions produced by spinal manipulation may play a prominent role in eliciting physiologic responses.
Chiropractic Subluxation Assessment:
What the Research Tells Us
J Canadian Chiropractic Assoc 2002; 46 (4): 215–220 ~ FULL TEXT
When you speak of subluxation, the first description that often jumps to mind is the traditional misalignment, occlusion of a foramen, pressure on a nerve and interference (MOPI) model proposed by B.J. Palmer.  In fact there are several modern models currently in use as well. Some are conceptual models, such as the Vertebral Subluxation Complex model of Faye and Lantz, [2 which proposes as many as nine components interacting in a complex.
Neurophysiological Effects of Spinal Manipulation
Spine Journal 2002 (Sep); 2 (5): 357–671
Biomechanical changes caused by spinal manipulation are thought to have physiological consequences by means of their effects on the inflow of sensory information to the central nervous system. Muscle spindle afferents and Golgi tendon organ afferents are stimulated by spinal manipulation. Smaller-diameter sensory nerve fibers are likely activated, although this has not been demonstrated directly. Mechanical and chemical changes in the intervertebral foramen caused by a herniated intervertebral disc can affect the dorsal roots and dorsal root ganglia, but it is not known if spinal manipulation directly affects these changes.
Effect of Chiropractic Treatment on the Endocrine and Immune System
in Asthmatic Patients
Proceedings of the 2002 International Conference on Spinal Manipulation
The broad aims of this FCER funded study is to determine whether stress is a factor in the pathophysiology of asthma and to determine if chiropractic management of asthmatics can alleviate stress induced asthma. More specifically for this meeting, our study aims to determine whether chiropractic treatment has beneficial effects on the endocrine system through measurement of salivary cortisol and on the immune system via salivary IgA determination. You can review other articles on this topic at the Chiropractic and Asthma Page.
The Functional Spinal Lesion:
An Evidence-Based Model of Subluxation
Topics In Clinical Chiropractic 2001 (Dec); 8 (1): 16–28 ~ FULL TEXT
The buckling model builds on clinical observations and supplements them with both direct and indirect biomechanical evidence. This model does not preconceive or proscribe any source of symptoms, but is able to accommodate the multifaceted clinical presentations of patients who respond favorably to manipulation/adjustment. It also can sustain a variety of hypothetical and evidence-based challenges. These findings offer an opportunity to reconceptualize and refine theoretical models of the spinal lesion into a platform for scientific, clinical, and political advancement of the profession.
The Effects of Mild Compression on Spinal Nerve Roots with Implications for Models of Vertebral Subluxation and the Clinical Effects of Chiropractic Adjustment
J Vertebral Subluxation Research 2001 (May); 4 (2): 1–13
There is evidence of nerve compression at the level of the intervertebral foramen (IVF) occurring anywhere from 15.4% to 78% of levels inspected. Most of the spines inspected were already prescreened to eliminate those that were definitely known to have nerve compression problems. Pressures as little as 10 mm Hg can alter the nerve root and dorsal root ganglion’s abilities to function normally. In the normal range of motion the pressures generated in the IVF may exceed 30 mm Hg. When considering the concept of a joint fixated in a diminished sphere of its normal range of motion in conjunction with the mild pressure increases, it becomes apparent that nerve function can be significantly altered.
Response of Muscle Proprioceptors to Spinal Manipulative-like Loads
in the Anesthetized Cat
J Manipulative Physiol Ther. 2001 (Jan); 24 (1): 2–11
The data suggest that the high-velocity, short-duration load delivered during the impulse of a spinal manipulation can stimulate muscle spindles and Golgi tendon organs more than the preload. The physiologically relevant portion of the manipulation may relate to its ability to increase as well as decrease the discharge of muscle proprioceptors. In addition, the preload, even in the absence of the impulse, can change the discharge of paraspinal muscle spindles. Loading of the vertebral column during a sham manipulation may affect the discharge of paraspinal proprioceptors.
Mechanical Force Spinal Manipulation Increases Trunk Muscle Strength Assessed By Electromyography: A Comparative Clinical Trial
J Manipulative Physiol Ther. 2000 (Nov); 23 (9): 585–595
The results of this preliminary clinical trial demonstrated that MFMA SMT results in a significant increase in sEMG erector spinae isometric MVC muscle output. These findings indicate that altered muscle function may be a potential short-term therapeutic effect of MFMA SMT, and they form a basis for a randomized, controlled clinical trial to further investigate acute and long-term changes in low back function.
Neurophysiologic Response to Intraoperative
Lumbosacral Spinal Manipulation
J Manipulative Physiol Ther. 2000 (Sep); 23 (7): 447–457
During the active trials, mixed-nerve root action potentials were observed in response to both internal and external spinal manipulative thrusts. Differences in the amplitude and discharge frequency were noted in response to varying segmental contact points and force vectors, and similarities were noted for internally and externally applied spinal manipulative thrusts. Amplitudes of mixed-nerve root action potentials ranged from 200 to 2600 mV for internal thrusts and 800 to 3500 mV for external thrusts.
The Reflex Effects of Subluxation: The Autonomic Nervous System
J Manipulative Physiol Ther 2000 (Feb); 23 (2): 104-106
There is no shortage of theories to explain the role of subluxation in disease and the effect of adjustment in relieving symptoms. The autonomic nervous system has often been invoked in constructing mechanisms to account for the effects of spinal dysfunction; recent investigations justify the attention that has been focused on this component of the nervous system. Recent neuroscience research supports a neurophysiologie rationale for the concept that aberrant stimulation of spinal or paraspinal structures may lead to segmentally organized reflex responses of the autonomic nervous system, which in turn may alter visceral function.
The Somatosensory System of the Neck and its Effects
on the Central Nervous System
J Manipulative Physiol Ther. 1998 (Oct); 21 (8): 553–563
Studies involving human and nonhuman vertebrates have provided considerable information about the anatomy of the sensory receptors located in the neck and about where information from these receptors is relayed in the spinal cord and brain. Physiological experiments involving electrical and natural stimulation of the head and neck regions have identified a role for some of these receptors in neck-evoked reflexes. It is clear that in addition to signaling nociception, the somatosensory system of the neck may influence the motor control of the neck, eyes, limbs, respiratory muscles and possibly the activity of some preganglionic sympathetic nerves.
Dysafferentation: A Novel Term to Describe the Neuropathophysiological Effects of Joint Complex Dysfunction. A Look at Likely Mechanisms of Symptom Generation
J Manipulative Physiol Ther 1998 (May); 21 (4): 267-280 ~ FULL TEXT
Since the founding of the chiropractic profession, very few
efforts have been made to thoroughly explain the mechanism(s) by
which joint complex dysfunction generates symptoms. Save for a
few papers, only vague and physiologically inconsistent
descriptions have been offered. The purpose of this article is to
propose a precise and physiologically sound mechanism by which
symptoms may be generated by joint complex dysfunction. This thought provoking FULL TEXT article was released exclusively to Chiro.Org by National College of
Chiropractic and JMPT. You may also enjoy this response from another chiropractic researcher.
Somatic Dysfunction and the Phenomenon of Visceral Disease Simulation: A Probable Explanation for the Apparent Effectiveness of Somatic Therapy in Patients Presumed to be Suffering from True Visceral Disease
J Manipulative Physiol Ther 1995 (Jul-Aug); 18 (6): 379–397
The proper differential diagnosis of somatic vs. visceral dysfunction represents a challenge for both the medical and chiropractic physician. The afferent convergence mechanisms, which can create signs and symptoms that are virtually indistinguishable with respect to their somatic vs. visceral etiologies, need to be appreciated by all portal-of-entry health care providers, to insure timely referral of patients to the health specialist appropriate to their condition. Furthermore, it is not unreasonable that this somatic visceral-disease mimicry could very well account for the "cures" of presumed organ disease that have been observed over the years in response to various somatic therapies (e.g., spinal manipulation, acupuncture, Rolfing, Qi Gong, etc.) and may represent a common phenomenon that has led to "holistic" health care claims on the part of such clinical disciplines.
Four Articles Which Describe the Relationship Between the Upper Cervical Spine and Headaches and Chronic Head Pain
Thanks to Rick Hallgren!
1. Atrophy of Suboccipital Muscles in Chronic Pain Patients
We have observed previously unreported muscle atrophy in the rectus capitis posterior minor (RCPMI) muscles of a group of chronic pain patients. We hypothesize that chronic pain, in this select group of patients, is a consequence of tramua that occurs to the C1 dorsal ramus during whiplash.
2. Magnetic Resonance Imaging of the Upper Cervical Spine
We are currently using MRI to investigate the functional integrity of the upper cervical spine. We started out looking for hypertonic muscles in a population of patients who were suffering from chronic head and neck pain. My first task was to collect MRI data and to identify suboccipital muscles within the MR images. So I brought together a physician and an anatomy professor to see if they could help me out. Their comments were classic. The anatomy professor said, "The reason you can't find those muscles is because they are not there." The physician immediately responded by saying, "No wonder these patients don't get any better." I had been using images that were collected from a chronic pain patient, and it was apparent that the rectus capitis posterior minor muscles were missing. When we looked at images from a control subject it was very easy to locate these muscles. At that point, the focus of our research switched from looking for hypertonic muscles to comparing muscle density between the control group and the chronic pain group.
3. Anatomic Relation Between the Rectus Capitis Posterior Minor Muscle and the Spinal Dura Mater
We observed that the PAO membrane was securely fixed to the surface of the dural tube by multitudinous fine connective tissue fibers. There was no real interlaminar space between these two structures and they appeared to function as a single entity. The influence of the RCPMI muscle on the dura mater was artificially produced in the hemisected specimen. Artificially functioning the muscle produced obvious movement of the spinal dura between the occiput and the atlas, and resultant fluid movement was observed to the level of the pons and cerebellum.
Visualization of the Muscle-Dural Bridge in the Visible Human Female Data Set
SPINE Journal 1995; 20 (23): 2484-2486
It has been speculated that the function of the muscle dural bridge may be to prevent folding of the dura mater during hyperextension of the neck. Also, clinical evidence suggests that the muscle dural bridge may play an important role the pathogenesis of the cervicogenic headaches.
The Neurophysiological Evaluation of the Subluxation Complex:
Documenting the Neurological Component with Somatosensory Evoked Potentials
Chiropractic Research Journal 1994; 3 (1) ~ FULL TEXT
The results seen in this study indicate highly significant changes for the pre vs post adjustment SSEP tests. The mean latencies decreased after chiropractic adjustment in each of the nerves tested. This would seem to indicate that the upper cervical subluxation does cause neurological compromise in nerves forming both the brachial and lumbo-sacral plexuses. The removal of the subluxation by chiropractic adjustment results in improved conduction of the neural impulses as demonstrated on the post-adjustment tests. The improvements that were observed are similar to the changes seen when neurological compromise is relieved by surgical procedures to decompress or stabilize the spine.
Subluxation and the Nervous System
Dynamic Chiropractic ~ February 12, 2004 ~ FULL TEXT
The important point to appreciate now is that the subluxation complex will alter the firing of spinal tissue nociceptors and mechanoreceptors, and this will lead to various symptoms that we often encounter in the clinical setting that respond to chiropractic care. So, when we think about subluxation, the subluxation complex, or joint dysfunction, we need to think about receptors and afferent fibers.
How Does Subluxation Affect the Nervous System?
Dynamic Chiropractic ~ October 7, 1996,
In 1976, Drs. Vert Mooney and James Robertson set out to confirm the earlier research on referred pain and discussed their findings in a well-known paper, "The Facet Syndrome."3 Their attention was directed toward the facet joints rather than spinal muscles and ligaments. The subjects in this study included five normal individuals and 15 patients with low back pain. To make a semi-long story short, Mooney and Robertson discovered that, indeed, injecting hypertonic saline into facet joints resulted in local and referred pain. They also discovered that, "slightly increasing the volume of injection would consistently increase the amount of pain radiation."
Nociception, Mechanoreception and Proprioception:
What's the Difference and What Do They Have to Do with Subluxation?
Dynamic Chiropractic ~ November 18, 1994
Nociception is the process by which nociceptive receptors receive tissue damaging stimuli that is then carried into the CNS by nociceptive axons (A-delta and C fibers). Potential outcomes of nociceptive input to the cord include pain, autonomic symptoms, vasoconstriction and muscle spasm. Nociceptive input to the cord appears to be the driving force behind the pathogenesis of subluxation (see Figure A). We must remember that nociception and pain are two completely different animals. However, a devastating consequence of both pain and nociceptive stimulation of the hypothalamus, is the release of cortisol by the adrenal glands. Over time, elevated levels of cortisol will promote glucose intolerance, inhibit collagen formation, increase protein breakdown, inhibit secretory IgA output, and inhibit white blood cell function. Clearly, the clinical importance of pain and nociception should not be minimized.
Nociception and Subluxation
Dynamic Chiropractic ~ September 23, 1994 ~ FULL TEXT
When discussing subluxation with our patients, the great majority of DCs still describe it in terms of a bone-out-of-place that pinches or chokes nerves. There are two major problems with this explanation: It is inaccurate because subluxations rarely, if ever, pinch or choke nerves. Secondly, by repeating this erroneous explanation again and again, DCs eventually come to believe it. Repetitive exposure to information embeds in the mind.