Whiplash Associated Disorder: The pathway from acute to chronic pain

By James Lehman

The whiplash injury was first coined in 1928 by orthopedist Harold Crowe. It is the most common type of non-fatal injury following motor vehicle crashes. The recovery is usually within two to three weeks, however, up to 42 percent of whiplash-type injured patients’ transition from acute to chronic pain, according to a 1994 article on whiplash injury.  

Chiropractors and other manual medicine providers commonly evaluate and manage these patients for the soft-tissue injuries to muscles, ligaments and nerves.  Frequently, biomechanical dysfunction occurs following strain of spinal muscles and/or sprain of spinal ligaments that cause acute neck pain and headaches.

In a 1996 prevalence study, researchers said, “neuroscientific studies have demonstrated…that whiplash patients suffer with chronic headaches and neck pain because of cervical zygapophyseal joint pain. Approximately 50 percent of these patients experience upper cervical spine joint pain and headaches, while 60 percent experience lower cervical spine joint pain and chronic neck pain following whiplash type injuries.”

Post-whiplash type injuries to the cervical facet capsules are a major cause of acute and chronic neck pain, according to a 2009 paper on the biomechanics of whiplash injury. The biomechanical rationale suggests that sprain injury or overstretching of the zygapophyseal joint capsules stimulates the firing of pain receptors, the study said.

It has also been demonstrated the spinal manual therapy has been effective with the treatment of chronic neck due to whiplash type injuries, which was examined in a 2010 randomized controlled trial.

In order to enhance quality of care, it is essential that clinicians comprehend the potential for acute pain becoming a chronic pain syndrome. At the first visit, it is recommended that a careful history and physical examination gather pertinent information about the nature of the condition.

A 2008 Swedish prospective study demonstrates that whiplash injured patients with neck pain before the accident, and a high degree of emotional distress from the accident, have a tenfold increased risk of developing chronic neck pain. Patients with moderate cervical sprain or strain injuries that do not resolve within weeks often exhibit a myriad of symptoms soon after the injury event, labeled as a Whiplash Associated Disorder (WAD), which Walter Spitzer, MD, and colleagues discussed in the November 1995 issue of the journal, Spine.

Mechanism of injury

Whiplash injury is “an acceleration-deceleration mechanism of energy transferred to the neck,” according to Spitzer and his colleagues, usually resulting from rear-end or side-impact motor vehicle collision. This whiplash motion has been shown to produce elongation and sub-failure strain of the facet capsular ligaments at the C6-7 level during the initial “S-shaped” phase, between zero and 75 milliseconds. As a result of the loss of the normal “C” shaped curve of the cervical spine (lateral view) and the subsequent “S” shaped curve, the facet capsular ligaments at the C2-3 level are also sprained and the paraspinal muscles strained.

Symptoms of a whiplash injury

Although the most common symptom experienced by a patient following a whiplash-type injury is pain and stiffness in the neck, a number of other symptoms should be recognized during the examination, which includes the following:

• Dizziness
• Visual and auditory disturbances
• Temporomandibular joint dysfunction
• Photophobia
• Dysphonia
• Dysphagia
• Fatigue
• Cognitive difficulties, such as concentration and memory loss, anxiety, insomnia, and depression 

While the signs and symptoms associated with WAD are diverse and at times confusing, the model presented by Walton and Elliott posits potential explanatory pathways that may demystify many of the more mysterious clinical presentations.

Pathoanatomical lesions

Chiropractors, physical therapists, and other manual medicine providers are charged with the responsibility to examine and perform a differential diagnosis that identifies all of the pathoanatomical lesions created by the whiplash-type of injury. It is essential that the initial evaluation rule-out fractures or dislocations of the spine.

The most common facets to be injured and highest prevalence of joint pain are at C2/C3 and C5/C6, which frequently results in referred pain to the head, shoulders, and thoracic spine. As a result of facet joint injury, whiplash patients frequently encounter, headaches, back, and shoulder pain, in addition to neck pain.

Unfortunately, many of these lesions are frequently not identified and treated appropriately. Largely undetected is the dorsal root ganglion lesion, which may contribute to adaptation in the overall functioning of the cervical dorsal root ganglion, and may predispose an individual to abnormal, centrally mediated pain processing.

Cervical disc injuries are present in 25 percent of subjects post whiplash injury and correlated with radicular symptoms. The C 5-6 segmental level was found to be the most common level of disc injury with a greater risk of low-grade spinal cord injury with pre-existing spinal canal narrowing at C5-6 level.

It has been my clinical experience that sprain injuries to the cervical spine because of whiplash-type injuries are not properly appreciated and recognized when determining prognosis.  Consequently, degenerative joint and disc disease occur and the patient experiences a post-traumatic cervical pain syndrome. Initially the identification of sprained ligaments and strained muscles may be performed with palpation and active, passive, and resistive range of motion testing, which is often referred to as the O’Donoghue’s maneuver. Patients suffering with persistent neck pain and other post-whiplash associated symptoms should be considered for specialized imaging to determine if cervical spine hypermobility or instability exists as a result of ligament laxity.

Turk’s diathesis-stress model

Clinicians often experience frustration with the patient that does not respond to treatment as expected based upon the patient’s post-whiplash pathoanatomical spinal lesions. Comprehension of Turk’s diathesis-stress model should alleviate the clinician’s frustration and enhance the prognosis of a patient suffering with post-whiplash chronic pain syndrome/illness. When a patient presents with psychological symptoms, including anxiety or a tendency to catastrophize over the symptoms, this patient is likely to centralize their pain and become a chronic pain patient, no matter the method used to treat.

Conclusions

Diagnosis is the key to successful treatment of whiplash-type injury. Yet, the prognosis determines the medical-legal consequences for both the patient and the provider.  If a patient presents post-whiplash injury with a history of previous neck pain, pathoanatomical lesions of the spine, and anxiety with catastrophizing of the symptoms, your prognosis should consider a chronic pain syndrome patient outcome.

References

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2. Lord SM, Barnsley L, Wallis BJ, Bogduk N. Chronic cervical zygapophysial joint pain after whiplash. A placebo-controlled prevalence study. Spine. 1996; 21:1737-1744; discussion 1744-1735. 
3. Chen HB, Yang KH, Wang ZG.  Biomechanics of whiplash injury. Chin J Traumatol 2009 Oct: 12(5):305-14.  
4. Sterling M, Pedler A, Chan C, Puglisi M, Vuvan V, Vicenzino B. Cervical lateral glide increases nociceptive flexion reflex threshold but not pressure or thermal pain thresholds in chronic whiplash associated disorders: A pilot randomised controlled trial. Man Ther. 2010 Apr; 15(2):149-53.   
5. Jouko Kivioja, Irene Jensen, and Urban Lindgren. Neither the WAD-classification nor the Quebec Task Force follow-up regimen seems to be important for the outcome after a whiplash injury. A prospective study on 186 consecutive patients. Eur Spine J. 2008 Jul; 17(7): 930–935. 
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10. Lord SM, Barnsley L, Wallis BJ, Bogduk N. Chronic cervical zygapophysial joint pain after whiplash. A placebo-controlled prevalence study. Spine. 1996; 21: 1737-1744; discussion 1744-1735.
11. Elliot JM, et al. Characterization of Acute and Chronic Whiplash-Associated Disorders. Journal of Orthopaedic & Sports Physical Therapy, 2009, Volume: 39 Issue: 5 Pages: 312-323. 
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