B02.24 Postherpetic myelitis

Name of the Condition

• Postherpetic myelitis

Summary

Postherpetic myelitis is a rare neurological complication of herpes zoster (shingles) that involves inflammation of the spinal cord. This condition typically occurs after a shingles outbreak and may lead to symptoms affecting motor, sensory, or autonomic function, depending on the spinal cord segments involved.

Causes

The primary cause is the reactivation of the varicella-zoster virus, which remains dormant in nerve tissue after an initial chickenpox infection. Reactivation can occur due to immune system suppression, allowing the virus to spread to the spinal cord and cause inflammation or nerve damage.

Risk Factors

• Increasing age, particularly in individuals over 50.
• A weakened immune system from conditions like HIV/AIDS, cancer, or immunosuppressive therapy.
• Severe or widespread shingles outbreaks.
• Pre-existing neurological conditions.

Symptoms

• Weakness or paralysis in limbs, often asymmetric.
• Sensory disturbances, such as numbness, tingling, or loss of sensation.
• Bladder or bowel dysfunction (e.g., incontinence or retention).
• Pain, burning, or a band-like sensation around the torso or limbs.
• Difficulty with coordination or balance.

Diagnosis

Diagnosis involves a combination of clinical evaluation, patient history (including recent shingles infection), and imaging studies (e.g., MRI) to identify spinal cord inflammation. Laboratory tests may confirm varicella-zoster virus activity.

Treatment Options

Treatment focuses on antiviral therapy (e.g., acyclovir) to target the virus, along with corticosteroids to reduce inflammation. Supportive care may include pain management, physical therapy, and management of autonomic dysfunction (e.g., bladder or bowel issues).

Prognosis and Follow-Up

Prognosis varies based on the extent of spinal cord involvement and timely treatment. Some patients experience partial or full recovery, while others may have persistent neurological deficits. Regular follow-up is necessary to monitor for complications and adjust management.

Complications

• Permanent weakness or paralysis.
• Chronic pain (neuropathic or myelopathic).
• Long-term bladder or bowel dysfunction.
• Respiratory impairment if upper spinal cord is affected.

Lifestyle & Prevention

• Vaccination against shingles (e.g., recombinant zoster vaccine) reduces risk of reactivation.
• Maintaining a healthy immune system through balanced nutrition and regular exercise.
• Prompt treatment of shingles to limit viral spread.

When to Seek Professional Help

Seek immediate medical attention if you experience sudden weakness, numbness, or bladder/bowel changes after a shingles outbreak, as these may indicate spinal cord involvement.

Tips for Medical Coders

Document the relationship between postherpetic myelitis and a preceding herpes zoster infection, as this supports the diagnosis. Ensure clinical notes specify spinal cord involvement and any associated neurological deficits to justify code assignment.