Pre and post operative motion analysis for evaluation of neck pain in chronic whiplash
From: J Brachial Plex Peripher Nerve Inj. 2009 Jul 17;4(1):10. [Epub ahead of print]
Chronic neck pain after whiplash is notoriously refractory to conservative treatment, and positive radiological findings to explain the symptoms are scarce. The apparent dis-proportionality between subjective complaints and objective findings is significant for the planning of treatment, impairment ratings, and judicial questions on causation. However, failure to identify a symptom’s focal origin with routine imaging studies does not invalidate the symptom per se. It is therefore not only of general interest to develop effective therapeutic strategies in chronic whiplash, but also to establish techniques for objective evaluation of treatment outcomes.
Twelve patients with chronic neck pain after whiplash underwent pre and post operative computerized 3-D gait analysis. Significant improvement was found in all gait parameters, cervical range of motion (ROM), and self-reported pain using the visual analog scale (VAS). Chronic neck pain is associated with abnormal gait patterns. 3-D gait analysis is a useful instrument to assess the outcome of treatment for neck pain.
Serious persistent problems after whiplash trauma to the neck, sometimes referred to as Whiplash Associated Disorders is a common and costly condition; estimates indicate an incidence of over 250,000 in the United States, at an annual cost in 2002 of $2.7 billion or close to $10,000 per incident. Although initial symptoms from acceleration-deceleration trauma to the neck may improve spontaneously or with physical therapy over the course of weeks-to-months, chronic and potentially disabling symptoms persist in a significant percentage of all cases. A complicating factor, which is also a reason for controversy, is the frequent failure of routine clinical laboratory investigative methods including MRI and electrodiagnostic studies, to objectively identify the cause of pain and other symptoms.
Although not a universal finding, stiffness of the neck and shoulders is a common sequela of whiplash. Using 3D motion analysis techniques, Dall’Alba et al. identified
significant limitations with a particular pattern of cervical range of motion among patients with Whiplash Associated Disorders, but also pointed out that their results do not provide an explanation for the loss of neck mobility. In a study where similar techniques were applied, Gargan et al found that cervical range of motion and psychological scores at three months were predictive of clinical outcomes at 2 years. Their findings were confirmed by Tomlinson et al in a follow-up study on the same
cohort, 7.5 years later.
Existing data suggest that neck stiffness in Whiplash Associated Disorders may be an expression of pain inhibition from soft tissue injury and painful muscle spasm without pathology of the spine. Thus, injections of Botox to trigger points in superficial neck muscles have been shown to provide temporary but significant decrease in pain and increase in cervical ROM, with similar effect of short duration from injections of local anesthetic to myofascial trigger points in the neck. While rarely a definitive solution to problems associated with the chronic whiplash syndrome, such injections may be helpful in identifying focal origin(s) of soft tissue pain.
The effect of lower segment dysfunction on the upper body kinematics has been previously investigated in normal controls and in patient groups with musculoskeletal disorders. The authors have not, however, found any studies exploring if standard gait parameters are impaired as a result of upper body dysfunction, The present investigation was designed for that purpose and, secondly, to assess the usefulness of computerized 3D gait analysis to objectively monitor outcomes of treatment for neck pain.
Significant improvement in three gait parameters were documented after treatment for neck pain from whiplash, a condition that because of a purported lack of diagnostic laboratory findings has been described by some authors as a social or emotional disorder in need of no treatment.
Pain related neck stiffness is a cardinal component of the chronic whiplash syndrome, but reliable assessment of cervical range of motion is highly dependent on the subject’s voluntary effort. Inclinometer or observation based techniques, or even computer-guided three dimensional measurement systems are therefore not ideal tools to objectively confirm or monitor chronic whiplash. In contrast, gait is a complex but highly automated function and therefore better suited for standardized analysis.
A clinically validated marker system was adopted for the purpose of this investigation, and the consistency of cervical range of motion was confirmed through repeated measurements in each participant since kinematic reproducibility has been established as a method to differentiate healthy subjects simulating neck pain from patients with true whiplash injuries. With these precautions, the authors consider the present findings reliable and valid.
Various kinematic abnormalities have been reported in chronic whiplash syndrome, often without conclusive evidence of their underlying cause(s). Thus, even though imaging evidence of abnormal cervical or craniocervical motion patterns have lead to recommendations to fuse the cranio-cervical joint complex, it has not been shown that a causative relation exists between such radiological findings and the clinical whiplash syndrome. Other investigators have interpreted patterns of oculomotor dysfunction in whiplash patients as evidence of brainstem injury, or “disorganized neck proprioceptive activity” leading to distortion of the posture control system. While none of the participants in this investigation had undergone specific diagnostic studies to assess brain stem function or cervical stability, the significant improvements in pain, cervical range of motion, and temporal-distance gait parameters illustrate that soft tissue surgery may alleviate considerable symptoms after whiplash in carefully selected patients.
The findings also allow the following conclusions: (1) Upper segment pain, e.g. in chronic whiplash syndrome, may be expressed as gait and posture abnormalities; and (2) Computerized 3D gait analysis provides objective data for diagnosis or outcome studies in chronic whiplash.
