J Orthop Sports Phys Ther 2009 (Sep); 39 (9): 658—664 ~ FULL TEXT
Ana I. De-la-Llave-Rincón, César Fernández-de-las-Peñas,
Domingo Palacios-Ceña, Joshua A. Cleland
Department of Physical Therapy, Occupational Therapy,
Rehabilitation and Physical Medicine,
Universidad Rey Juan Carlos,
Alcorcón, Madrid, Spain.
STUDY DESIGN: Case control study.
OBJECTIVES: To compare the amount of forward head posture (FHP) and cervical range of motion between patients with moderate carpal tunnel syndrome (CTS) and healthy controls. We also sought to assess the relationships among FHP, cervical range of motion, and clinical variables related to the intensity and temporal profile of pain due to CTS.
BACKGROUND: It is plausible that the cervical spine may be involved in patients with CTS. No studies have investigated the possible associations among FHP, cervical range of motion, and symptoms related to CTS.
METHODS: FHP and cervical range of motion were assessed in 25 women with CTS and 25 matched healthy women. Side-view pictures were taken in both relaxed-sitting and standing positions to measure the craniovertebral angle. A CROM device was used to assess cervical range of motion. Posture and mobility measurements were performed by an experienced therapist blinded to the subjects' condition. Differences in cervical range of motion were examined using the nonparametric Mann-Whitney U test. A 2-way mixed-model analysis of variance (ANOVA) was used to evaluate differences in FHP between groups and positions.
RESULTS: The ANOVA revealed significant differences between groups (F = 30.4; P<.001) and between positions (F = 6.5; P<.01) for FHP assessment. Patients with CTS had a smaller craniovertebral angle (greater FHP) than controls (P<.001) in both standing and sitting. Additionally, patients with CTS showed decreased cervical range of motion in all directions when compared to controls (P<.001). Only cervical flexion (rs = -0.43; P = .02) and lateral flexion contralateral to the side of the CTS (rs = -0.51; P = .01) were associated with the reported lowest pain experienced in the preceding week. A positive association between FHP and cervical range of motion was identified in both groups: the smaller the craniovertebral angle (reflective of a greater FHP), the smaller the range of motion (r values between 0.27 and 0.45; P<.05). Finally, cervical range of motion and FHP were negatively associated with age in the control group but not in the group with CTS.
CONCLUSION: Patients with mild/moderate CTS exhibited a greater FHP and less cervical range of motion, as compared to healthy controls. Additionally, a greater FHP was associated with a reduction in cervical range of motion. However, a cause-and-effect relationship cannot be inferred from this study. Future research should investigate if FHP and restricted cervical range of motion is a consequence or a causative factor of CTS and related symptoms (eg, pain).
From the FULL TEXT Article:
Carpal tunnel syndrome (CTS) is a complex musculoskeletal disorder usually associated with localized compression of the median nerve at the location of the carpal tunnel. Atroshi et al  reported prevalence rates of 3.8% (95% confidence interval [CI]: 3.1%-4.6%) for women and 2.7% (95% CI: 2.1%-3.4%) for men. Bongers et al  have recently reported that the incidence rate of CTS was 1.8/1000 (95% CI: 1.7-2.0).
Although the etiology and pathology of CTS is a topic of debate, evidence exists to suggest that CTS is not exclusively a local neuropathy. Zanette et al  reported that 45% of patients with CTS exhibited proximal pain, (ie, pain throughout the upper extremity). Chow et al  found that neck pain was present in 14% of patients with CTS. Finally, Reading et al  determined that symptoms involving the sensory distribution of the median nerve can be related to neck disorders. Therefore, it seems plausible that the cervical region may also be involved in patients with CTS.
Proper posture is considered crucial for musculoskeletal balance and theoretically involves a minimal amount of stress and strain on the body. One of the most common postural abnormalities identified in clinical setting (66%) is a forward head posture (FHP), which implies that the head is anterior to a line passing through the center of gravity of the body.  FHP has been previously identified in patients with neck pain,  temporomandibular disorders,  postconcussion headache,  cervicogenic headache,  chronic tension-type headache,  and migraine.  In addition, restricted cervical range of motion has also been found in patients with tension-type or cervicogenic headache. 
It has been reported that there is a significant correlation between cervical spine arthritis and the presence of CTS.  Hurst et al  reported that the presence of arthritis in the cervical spine may result in compression of the cervical nerve roots, predisposing patients to developing CTS via the “double-crush syndrome.” The double-crush syndrome refers to the coexistence of dual compressive lesions along the course of a nerve.  This concept hypothesizes that impingement of a peripheral nerve of the upper extremity, for instance the median nerve, may result in a complex clinical presentation in which a single lesion in the course of the proximal portion of a nerve predisposes that nerve to a second lesion further along its distal portion, particularly when it passes through a narrow anatomical canal (eg, carpal tunnel). In agreement with this hypothesis, Pierre-Jerome and Bekkelund  demonstrated that patients with CTS experienced a higher incidence of narrowing of the cervical foramen when compared to healthy controls. These authors hypothesized that the compromised neural foramen could potentially lead to nerve compression and possibly a double-crush syndrome in patients with CTS.  Accordingly, it is possible that a FHP may compromise cervical nerve roots, rendering the subject more susceptible to developing CTS.
To our knowledge, no researchers have previously investigated the possible connection among FHP, cervical range of motion, and the symptoms associated with CTS. The main purpose of this study was to investigate differences in both FHP and cervical range of motion between patients with CTS and healthy controls. Additionally, a second aim was to investigate the possible relationship among FHP, cervical range of motion, and clinical variables quantifying the intensity and temporal profile of pain due to CTS. Finally, because range of motion has been shown to decrease with age,  we also investigated if cervical range of motion and FHP were correlated with age in patients with CTS.
The results of our study demonstrated that patients with moderate CTS had a greater FHP and decreased cervical range of motion when compared to healthy subjects. FHP was associated with cervical range of motion, with greater FHP being related to a lower amount of cervical range of motion. However, neither FHP nor cervical range of motion were related to clinical pain features due to CTS.
The results of our study are similar to those that have identified the presence of FHP and restricted cervical range of motion in other populations with musculoskeletal disorders. FHP has been previously identified in patients with different types of headaches. Watson and Trott  reported that patients with cervicogenic headaches had a smaller craniovertebral angle (greater FHP) than healthy subjects (mean ± SD, 44.5° ± 5.5° versus 49.1° ± 2.9°; P<.001). Treleaven et al  found that patients with postconcussion headaches also had a smaller craniovertebral angle (mean ± SD, 46.7° ± 2.8°) than healthy controls (50.7° ± 7.9°). Additionally, Fernández-de-las-Peñas et al  reported that patients with chronic tension-type headache exhibited a smaller craniovertebral angle (mean ± SD, 45.3° ± 7.6°) when compared to healthy subjects (54.1° ± 6.3°; P<.001). We have also previously identified that the craniovertebral angle was smaller in patients with unilateral migraine (mean ± SD, 42.2° ± 6.4°) when compared to controls (52.6° ± 7.2°; P<.001).  Our group of patients with CTS also showed a smaller craniovertebral angle, confirming than FHP is present in patients with CTS. Because FHP is also related to other pain conditions, [7, 89, 10, 13, 31, 34] the change of head posture may be a consequence (ie, an antalgic posture in trying to reduce pain, rather than a possible etiologic factor). This is supported by the fact that neither FHP nor cervical range of motion was found to be related to function nor symptom severity due to CTS in this study. Therefore, a cause-and-effect relationship cannot be established with the current study. Whether FHP and restricted cervical range of motion is a consequence of the pain or a causative factor in patients with CTS requires further investigation.
In a meta-analysis, Chen et al  reported the following normative values for cervical range of motion:
flexion/extension, 150°-116° (flexion, 69°-48°;
lateral flexion, 108°-76° (1 side, 49°-38°);
rotation, 186°-136° (1 side, 93°-70°).
Based on these data, most of the subjects (n = 24 [96%]) within the control group were in the upper 50% of the normative values and most of the patients with CTS (n = 22 [88%]) were below normative values. Therefore, we conclude that our healthy control group presented with normal cervical range of motion, and that most of our individuals in the patient group exhibited a decrease in cervical range of motion. Nevertheless, cervical range of motion of 3 patients with CTS (12%) falls within the lower value of 95% CIs of the normative values.
Additionally, cervical range of motion has been shown to decrease with age.  We found that cervical range of motion decreased with age in our healthy control group, but not in the patients with CTS. Because the groups were age matched, age cannot explain the decreased in cervical range of motion found in patients with CTS.
A statistically positive correlation was found between FHP and cervical range of motion for all directions: subjects with a greater FHP (ie, smaller craniovertebral angle) showed less cervical range of motion. Our results are in agreement with previous studies which also found that FHP was inversely correlated with the amount of cervical range of motion. [21, 33] This is expected, as FHP may lead to compression on the facet joints affecting the biomechanics of the head/neck. However, it should be recognized that, although the correlations were statistically significant, they were low to moderate (0.25-0.45).
Considering the increased FHP and restricted neck range of motion in our sample of patients with CTS, we hypothesize that perhaps treatment directed at the cervical spine may enhance the outcomes of patients with CTS. Preliminary evidence suggests that a therapeutic approach including interventions targeted at the neck region may be helpful in reducing pain and improving function in CTS. Valente and Gibson  have reported the outcomes of a patient with CTS who was treated with a multimodal approach including techniques directed at the cervical spine. After 12 treatments, the patient exhibited improvements in grip strength and a normalization of motor and sensory latencies of the median nerve.  However, a cause-and-effect relationship cannot be inferred from a case report. Hence, future clinical trials should investigate the effects of treatment directed at the cervical spine in patients with CTS.
There exist a few limitations to the current study. First, we used a relatively small sample size from 1 specialized hospital. Future studies with larger sample sizes should continue to investigate abnormalities of FHP and cervical range of motion and their association with clinical pain features of CTS. Additionally, the results of our study do not allow us to make inferences regarding the clinical relevance of FHP and restricted cervical range of motion in the natural course of CTS. Future trials should investigate if physical therapy management directed at the cervical spine changes the symptoms and severity of CTS.
Patients with mild or moderate CTS exhibited greater FHP and greater restrictions in cervical range of motion as compared to matched healthy controls. Additionally, FHP was
correlated with cervical range of motion: the greater the FHP, the lesser the range of motion. Neither FHP nor cervical range of motion was related to clinical pain features due to CTS. Further research is needed to clearly define the potential role of both FHP and restricted cervical range of motion in both the etiology and the perpetuation of CTS.
FINDINGS: Patients with mild or moderate CTS exhibited a greater FHP and less cervical range of motion compared to matched healthy controls. A more pronounced FHP was associated with reduced cervical range of motion. Neither FHP nor cervical range of motion was related to clinical pain features due to CTS.
IMPLICATIONS: Treatment directed at correction of FHP and limitations of cervical range of motion may be worth considering as part of the treatment for individuals with CTS.
CAUTION: We used a relatively small sample size from 1 specialized hospital. The study design does not allow us to make inferences about a cause-and-effect relationship between CTS, FHP, and cervical range of motion.