Chronic / Acute Conditions

Herpetic Neuralgia and Motor Vehicle Collision (MVC) Injury

Nancy Martin-Molina, DC, QME, MBA, CCSP

History

The patient is a pleasant but anxious 70-year-old female with a recent history of a low-impact, rear-ended automobile accident while she was traveling as a passenger. Her symptoms had started almost immediately following the accident; she began to experience sharp pain in her neck with some radiation into her right shoulder. Significant medical history for the injured region included antiviral treatment from a medical prescriber for herpes zoster (HZ), along a cervical spinal dermatome dated back to one year ago. Her neck pain was rated as 8 on a scale of 1-10, with 10 being severe pain and moderate interference in activities of daily living. The quality of the neck pain is described as stabbing, aching and "grabbing." The right shoulder radiation is intermittent with pins and needles.

Exam findings: Chiropractic spinal listings are detected at vertebral levels C0/1, C4/5, and T8/T9. There is some tenderness at the right sternocleidomastoid, none at the suboccipital, and some facetal tenderness. No Adam's sign (scoliosis) is noted. Testing sensory discrimination in right upper extremities C4 dermatomes demonstrates heightened sensitivity. Multiple zosteriform - well-healed, scar-type clusters - are seen along this right C4 dermatome.

Radiological findings: Cervical lordosis is nonmaintained, and measurements reveal 28 degrees with room for a radiological disparity of +/- 7 degrees. There is a moderate loss in disc height, sclerosis and osteophytes projection involving cervical fourth, fifth, sixth and seventh levels.

The bone density and remaining soft-tissue structures are remarkable for pencil-thin cortices and increased trabaculae pattern. Instability is demonstrated with widened interspinous spacing of the cervical third and fourth level. AP view: uncinate processes and adjacent fossae show projecting osteophytes and sclerosis.

Discussion

With post-impact collision forces, the risk of post-herpetic neuralgia (PHN) must be considered even in patients who have never suffered herpetiform lesions, and is around 20 percent in patients over 60 years of age (some sources say as high as 40 percent), as local trauma to the sensory ganglia is a predisposing factor. This illness is recognized as an acute local infection caused by the varicella-zoster virus (VZV). It is characterized by unilateral pain and a vesicular or bulbous eruption limited to a dermatome innervated by a corresponding ganglia. The viral outbreak can cause local nerve-tissue swelling and reduced blood flow, and permanent nerve destruction affecting the dorsal-horn sensory-processing centers, the dorsal-root ganglion, and also the peripheral sensory receptors in the area of the affected skin. Destruc-tion of these different nerve areas leads to PHN; whether or not PHN develops after an acute attack of the HZ virus depends on age.

In this case scenario, we must also consider the spinal disc and surrounding joint capsule as a source of neck pain following the collision. Based on the mechanism of injury and the patient's age, we may see that the cervical joint capsule is susceptible to being partially inflamed from the insult of the forced whipping injuries. In the medical literature, neck-injury tolerance has been shown to be correlated with vector of collision, age and occupant positioning.

Age is more significant than velocity in MVC outcomes. Older people have sacropenia or decreased muscle mass. Meaning "poverty of flesh" in Greek, sacropenia is the degenerative loss of skeletal muscle mass and strength associated with senescence. It is actually not a disease itself, but a medical term describing marked or visible loss of musculoskeletal mass, strength and integrity. By age 50, individuals lose approximately 30 percent of their muscle mass. Thus, the connective tissues have increased density and decreased water as one ages, and there is strong evidence of a decreased capacity for repair.

PHN is simply defined as persisting pain in the area of the rash once the HZ lesions have healed. It presents as extreme sensitivity of the skin in the area affected by the HZ rash, especially to light touch and brushing by clothing. The sensitivity seems to be worse in the whiter, scarred areas of the skin, which have lost their pigmentation. Spontaneous pain in the area may be aching or stabbing in nature. Secondary musculoskeletal problems (muscles, joints) are caused by excessive guarding of the affected area. This pain can then contribute to the overall clinical picture, adding movement-induced pain.

Case management in this scenario included specialty referral to neurology and pain management specialists. The patient's care concluded uneventfully after the fourth month of chiropractic care.

November 2008
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