CHAPTER SYNOPSIS:

Posttraumatic neck pain is incompletely understood. Most cases of pain from whiplash incidents resolve with conservative therapy, but some patients require targeted injections or nerve ablation. Surgical intervention is rarely required. Posttraumatic arthritis of the cervical spine is poorly represented in the literature, and little data exist describing its incidence, treatment, and natural history.

IMPORTANT POINTS:

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  The facets are the major generators of pain in cases of chronic whiplash syndrome.

  
  
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  Targeted injections of the medial branches of the cervical dorsal rami and discography can help in identifying the pain generator.

  
  
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  Arthrodesis results in good outcomes in properly selected patients.

CLINICAL PEARLS:

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  Initial evaluation of a patient with posttraumatic cervical pain must include both static and flexion/extension radiographs.

  
  
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  Posttraumatic pain without radiographic evidence of disease is treated without surgery.

  
  
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  Percutaneous radiofrequency neurotomy can be useful in cases of refractory neck pain without radiographic evidence of disease.

CLINICAL PITFALLS:

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  If initial radiographs are negative, use advanced imaging such as computerized tomography to detect occult fractures.

  
  
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  Additional testing such as facet injection, discography, or both can aid in determining the exact source of the pain for surgical planning when nonoperative treatment fails.

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POSTTRAUMATIC PAIN SYNDROMES

Whiplash is the classic minor injury to the cervical spine. Minor implies that no fractures or dislocations have occurred and the injury is limited to the soft tissues. Whiplash occurs when the patient’s body is accelerated as a result of a rear-end collision. The force from the impact causes a forward and upward displacement of the torso, with head motion lagging behind. The cervical spine is deformed into a nonphysiologic “S” shape in which the lower cervical vertebrae are extended whereas the upper vertebrae are flexed ( Fig. 8-2 ). The facets of the lower cervical spine are impacted into each other posteriorly and are distracted anteriorly. Facet injuries resulting from whiplash range from capsular strains or tears, to cartilage damage, to frank fractures. The intervertebral disc and longitudinal ligaments are distracted during the deformation, resulting in tearing of the annulus fibrosis, which can be associated with subsequent disc herniations. Whether patients who have undergone anterior cervical discectomy and fusion (ACDF) or those who have undergone disc arthroplasty are more at risk is currently debatable.

The motion of the cervical spine during whiplash. Impaction of the facets of the lower cervical spine and stretching of the anterior structures occur during the S-shaped deformation phase, and most injury is thought to result during that phase.

Patients can experience chronic neck pain not explained by any radiographic or advanced imaging workup, which is not clearly understood. Axial neck pain and headaches are the two most common complaints associated with whiplash. Radicular pain might also be present but is less common. Facet joint injury has been shown to be the most common source of pain in association with chronic whiplash syndrome. Lord et al., in a placebo-controlled study involving targeted facet injections, showed that the facets were the pain generator in 60% of patients with chronic whiplash pain. Discoligamentous injuries comprise the remaining causes of pain in cases of chronic whiplash syndrome and may be more apparent on magnetic resonance images than are facet injuries.

Although the majority of patients who sustain whiplash injury fully recover within 3 to 6 months, 10% to 40% of patients with whiplash injury continue to experience symptoms after 2 or more years. Most of those who are symptomatic experience only mild symptoms, but 5% to 7% experience severe symptoms with partial or complete disability. The strongest predictor of chronic pain is higher pain intensity with the original injury, suggesting that patients with chronic pain suffered more severe injury. The importance of psychosocial factors and litigation is controversial and must be considered. However, some studies have shown little or no effect on outcome. Chronic neck pain after whiplash injury typically has nonspecific radiographic and magnetic resonance imaging findings, although Radanov et al. show that patients in whom the pain persisted for a longer duration had more signs of preexisting arthritis of the cervical spine.

POSTTRAUMATIC ARTHRITIS

Chronic neck pain and posttraumatic arthritis after more serious cervical spine injuries are not well reported in the literature. Posttraumatic degeneration and arthritis result from a combination of the initial injury and the ensuing facet joint incongruity and spinal deformity. Posttraumatic arthritis of the cervical spine commonly presents as neck pain, interscapular pain, and restriction of cervical motion. Arthritis caused by injury of the upper cervical spine or the craniocervical junction might also present as occipital or cervicogenic headaches. Weather-related phenomena often exacerbate the symptoms.

Many patients with fracture of the atlas, including those treated without and with surgery, have long-term symptoms of axial neck pain, dysesthesias, and limited range of motion. Levine and Edwards report that neck pain can persist in as many 80% of patients who have sustained a four-part burst fracture of the atlas. Similarly, fractures involving the lateral masses, occiput-C1 facet joints, and C1-2 facet joints have worse long-term symptoms and increased incidence of degenerative changes. Arthritis can be observed in the C1-2 joint after occipital condyle fractures, but the incidence is unknown because of the low survivorship after serious injuries to the occipitocervical junction. This condition presents with rotation-related pain.

Approximately 10% of patients with traumatic type I spondylolisthesis of the axis experience symptomatic degenerative changes at C2-3. The hyperextension mechanism that commonly causes traumatic spondylolisthesis results in significant crushing of the C2-3 facet joint and its cartilage, and is theorized to lead to posttraumatic arthritis. This is evidenced by loss of facet joint space with specific localized pain in that region of the spine. Degeneration is more common in type I injuries because type II injuries may lead to spontaneous anterior fusion.

Fractures that involve the lateral masses of the lower cervical spine can cause facet joint incongruity, kyphosis, and subsequent degeneration. The amount of displacement that can be tolerated by the facets of the cervical spine without the development of posttraumatic arthritis is unknown. Patients with facet dislocations have been shown that successful long-term outcomes correlate with anatomic alignment for both nonoperative and operative treatment. Rorabeck et al. reports a 70% rate of disabling pain for patients in whom unilateral facet joint dislocation was not congruently reduced.

Posttraumatic deformities that cause residual kyphosis can lead to facet degeneration. This occurs by the adjacent vertebral levels hyperextending in an attempt to compensate for the loss of cervical lordosis in a kyphotic spine. This, in turn, places added stress to the joints, which leads to early degenerative changes and pain.

Degenerative arthritis can develop at adjacent levels after arthrodesis for cervical spine fracture-dislocation. A study of 45 patients who underwent anterior corpectomy and fusion for cervical spine injuries reported a 68% incidence rate of radiographically shown degeneration. Similar rates of degeneration were observed in the younger and older patient groups, suggesting that factors other than natural progression of preexisting degenerative disease must be involved. This is in contradistinction with adjacent segment disease after ACDF for routine cervical spondylosis, which is thought to be caused mainly by the progression of spondylosis. The traumatic episode itself can cause damage to the adjacent segments that is subclinical at the time of injury but presents months to years later with degenerative changes.

McGrory and Klassen have conducted a long-term study with a mean follow-up duration of 17.5 years. The study participants included children and adolescents who underwent anterior or posterior arthrodesis for cervical spine trauma and showed greater rates of degenerative arthritis than would be expected for patients of similar age. The prevalence of arthritic changes was increased in patients with longer follow-up duration. Of those followed for more than 20 years, 67% showed evidence of degeneration. Patients with arthritic changes had clinically significant decreased range of motion compared with those without, but none required further surgical intervention as of the time of the report.