B00.82 Herpes simplex myelitis

Name of the Condition

• Herpes simplex myelitis

Summary

Herpes simplex myelitis is a rare but serious neurological condition caused by the herpes simplex virus (HSV), resulting in inflammation of the spinal cord. The infection can lead to acute or subacute neurological deficits, with symptoms ranging from mild sensory changes to severe motor impairment. The condition typically arises from direct viral invasion of the spinal cord, often following primary infection or reactivation of HSV.

Causes

Herpes simplex myelitis is caused by the herpes simplex virus (HSV), a member of the Herpesviridae family. The virus infects the spinal cord, leading to inflammation and potential tissue damage. Transmission may occur through primary HSV infection or reactivation of latent virus, with hematogenous spread or direct extension from adjacent tissues. HSV-1 and HSV-2 are the primary subtypes associated with this condition.

Risk Factors

• Immunocompromised states, such as HIV/AIDS, chemotherapy, or chronic steroid use.
• Advanced age or neonatal status, which may increase susceptibility to severe disease.
• Prior HSV infection, as reactivation is a common trigger.
• Skin barrier disruptions, including burns or eczema, facilitating viral entry.
• Close contact with individuals with active HSV infections or asymptomatic shedding.

Symptoms

• Acute or subacute onset of neurological deficits, such as weakness, numbness, or paralysis.
• Sensory disturbances, including pain, tingling, or loss of sensation in affected areas.
• Bladder or bowel dysfunction, including incontinence or retention.
• Fever, malaise, or systemic symptoms in some cases.
• Asymmetric or symmetric motor involvement, depending on the spinal cord region affected.

Diagnosis

Diagnosis involves a combination of clinical evaluation, imaging, and laboratory testing. Magnetic resonance imaging (MRI) of the spine may show characteristic inflammatory changes in the spinal cord. Cerebrospinal fluid (CSF) analysis often reveals pleocytosis, elevated protein, and may detect HSV DNA via polymerase chain reaction (PCR). Serological testing for HSV antibodies can support the diagnosis, though PCR is more specific for acute infection. Differential diagnosis includes other infectious or inflammatory myelopathies.

Treatment Options

Treatment typically includes antiviral therapy, such as acyclovir or valacyclovir, to target HSV replication. High-dose intravenous antivirals are often initiated early to reduce viral load and prevent further damage. Corticosteroids may be used in select cases to reduce inflammation, though their role is controversial. Supportive care, including pain management, physical therapy, and management of bladder or bowel dysfunction, is essential. Treatment duration and intensity depend on disease severity and patient response.

Prognosis and Follow-Up

Prognosis varies based on the extent of spinal cord involvement and timely treatment. Early antiviral therapy improves outcomes, but some patients may experience residual neurological deficits. Follow-up includes monitoring for symptom progression, rehabilitation needs, and potential complications. Long-term care may involve physical therapy, occupational therapy, or assistive devices to manage functional impairments. Regular neurological assessments are recommended to track recovery.

Complications

• Permanent neurological deficits, such as paralysis or sensory loss.
• Chronic pain or neuropathic symptoms.
• Bladder or bowel dysfunction requiring ongoing management.
• Recurrent HSV reactivation or dissemination.
• Secondary infections due to immobility or impaired sensation.

Lifestyle & Prevention

• Maintain good hygiene to reduce HSV transmission risk.
• Avoid close contact with individuals during active HSV outbreaks.
• Manage immunocompromising conditions to lower susceptibility.
• Practice safe sex to reduce genital HSV transmission.
• Seek prompt medical care for HSV symptoms to prevent complications.

When to Seek Professional Help

Seek immediate medical attention if you experience sudden neurological symptoms, such as weakness, numbness, or bladder/bowel changes, especially if you have a history of HSV infection. Early evaluation is critical to initiate antiviral therapy and minimize spinal cord damage.

Tips for Medical Coders

Document the specific type of herpes simplex virus (HSV-1 or HSV-2) if known, as this may impact coding specificity. Include details on the onset (acute vs. subacute), affected spinal cord regions, and any associated complications. Ensure documentation supports the use of B00.82 by confirming herpes simplex as the cause of myelitis. Note any imaging or laboratory results that confirm the diagnosis.