by Jacob W. Gent, Attorney at Law
Nikolai Bogduk, MD, PhD, in a recent narrative review published in Spine, summarized evidence which demonstrates that injuries to the cervical zygapophysial (also known as facet) joints are the primary source of pain following hyperflexion-hyperextension injuries following motor vehicle collisions. In addition, data from studies conducted by a variety of divergent disciplines conclude these symptoms may be effectively treated through use of radiofrequency neurotomy where conservative modalities are not successful.
Examination of cervical spines of persons killed in motor vehicle collisions identified a number of non-lethal injuries including a variety of injuries to the cervical facet joints, such as intra-articular hemorrhages and lesions, as well as fractures to the subchondral bone, articular cartilage, and articular process. According to the studies, virtually none of the lesions to the facet joints were present on postmortem radiography.
In vivo studies of the biomechanical causes of post-whiplash neck pain demonstrate the cervical spine is compressed from below as the trunk rises toward the head. This causes sigmoid deformation when the lower cervical spine is subjected to an abnormally high posterior sagittal rotation. The upper vertebrae rotate in a sagittal direction with practically no posterior translation. The anterior vertebral margins are widely separated, while the posterior inferior articular processes carve into the superior articular surface of the adjacent lower vertebral body. These abnormal movements produce posterior facet joint lesions and rim lesions of the intervertebral disc due to avulsion of the annular fibrosis from the vertebral endplate.
During hyperflexion-hyperextension injuries, the facet joints are initially compressed beyond normal physiological limits, followed by excessive straining to the capsule and annulus fibrosis. The amount of stress increases with the level of impact during trauma. Studies show the C4-5 disc is particularly susceptible to injury in a relatively low speed impact, while C3-4,C5-6 and C6-7 are at increased risk as impact acceleration increases
A study of post-whiplash lesions in 21 cadavers found intervertebral disc injuries in 90% of the subjects, anterior longitudinal ligament tears in 80% of the cadavers, and a 40% incidence rate of facet capsule joint tears. Other injuries included tears of the annulus fibrosis, anterior longitudinal ligament, and facet joints.
Excessive stretching of the facet joint capsules was present in studies subjecting animals to hyperextension-hyperflexion forces similar to motor vehicle collisions, resulting in sustained, elevated nociceptor activity. Downstream changes in the central nervous system were produced with increased nociceptor activity, demonstrating a physiological link between the trauma and facet joint generated pain.
Medial Branch Blocks
Cervical facet joint pain which does not resolve with conservative modalities such as chiropractic, physical therapy and/or massage can be further assessed with cervical medial branch blocks. This diagnostic tool assesses pain originating from the facet joint. The procedure involves anesthetizing one or two nerves which innervate a specific joint with a small amount of local anesthetic. A positive response occurs when pain is completely relieved following the injection. Several studies involving cervical medial branch blocks at various treatment facilities have produced similar results: approximately 50% of all patients with chronic neck pain, either with or without a history of hyperflexion-hyperextension injuries, experience cervical facet mediated pain. The most commonly affected joints were C2-3 or C5-6 individually, followed by a combination of C5-6 and C2-3. Symptoms involving a combination of the C5-6 and C6-7 joints occurred less frequently. Study findings support the proposition that zygapophysial joints can be injured, and as a result, serve as a source of pain. Further, facet joint injuries are the single most common source of pain for patients with whiplash injuries. Regarding cervical medial branch blocks, Dr. Bogduk noted:
- No other diagnostic procedure or technique has been tested and validated as extensively as cervical medial branch blocks.
- No study has produced data on any other source of pain to rival the prevalence of zygapophysial joint pain.
Cervical facet joint pain which does not resolve with conservative modalities and have a positive response to the cervical medial branch blocks can be treated with cervical medial branch radiofrequency neurotomy. This procedure involves the coagulation of the medical branch nerves innervating the affected joint or joints by use of percutaneous electrodes. A substantial number of patients, properly screened through use of controlled medial branch blocks, achieved complete relief of their cervical facet pain following an accurate radiofrequency surgical procedure. A placebo-controlled trial conclusively demonstrated that active treatment resulted in successful outcomes with longer periods of relief in a greater number of patients, compared to patients undergoing sham surgical procedures. Success is defined as complete relief of pain, where the patient is able to return to their activities of daily living without ongoing symptoms or the need for ongoing treatment. Neurotomy procedures were successful 70% of the time, with pain relief lasting for a median duration of 400 days. More recent studies reveal that repeat neurotomy is successful in eliminating symptoms in patients whose symptoms returned, and that such relief could be maintained for several years. Furthermore, outcomes for patients involved in litigation were not significantly inferior statistically than for patients not engaged in litigation.
Patients experiencing acute or chronic cervical pain as the result of another person’s negligence would benefit from a complimentary consultation with the attorneys at Adler Giersch, ps. Not everyone needs to retain an attorney, but those with traumatic injuries would benefit from a legal consultation with an experienced attorney.
 Spine, December 1, 2011; Vol. 36, 25S, S194-S199. [Internal citations omitted.]