What is the treatment for herpes zoster encephalitis?

Treatment for Herpes Zoster Encephalitis

For herpes zoster encephalitis, intravenous acyclovir at a dose of 10-15 mg/kg three times daily for 14-21 days is the recommended treatment, with consideration of adjunctive corticosteroids if there is evidence of vasculopathy. 1

Antiviral Therapy

Dosing Recommendations

• Adults and children >12 years: 10-15 mg/kg IV every 8 hours 1
• Children 3 months-12 years: 10-15 mg/kg IV every 8 hours 1
• Duration: 14-21 days 1

Rationale

• VZV is less sensitive to acyclovir than HSV, which is why the higher dose of 15 mg/kg may be considered when renal function is normal 1
• Early initiation of therapy (within a few days of symptom onset) is associated with better outcomes 1, 2
• A small study of 14 patients with herpes zoster associated encephalitis showed beneficial effects with acyclovir treatment 2

Adjunctive Corticosteroid Therapy

Recommendations

• If vasculopathy (stroke) is present: Corticosteroids are recommended (e.g., prednisolone 60-80 mg daily for 3-5 days) 1
• For standard VZV encephalitis: Corticosteroids may be considered, though evidence is limited 1

Rationale

• The inflammatory nature of VZV-associated vasculopathy provides a stronger rationale for corticosteroid use 1
• Unlike in HSV encephalitis where corticosteroid use remains controversial, there is more acceptance of their use in VZV encephalitis with vasculopathy 1

Monitoring and Follow-up

During Treatment

• Regular monitoring of renal function, especially after 4 days of therapy when nephrotoxicity risk increases 3
• Monitor for signs of acyclovir-associated nephrotoxicity (13-21% prevalence) 4
• Dose adjustment for patients with renal impairment 3

After Treatment

• Consider repeat CSF examination to confirm viral clearance 1
• Monitor for potential relapse, though this appears less common with VZV than HSV encephalitis 5

Special Considerations

Immunocompromised Patients

• May require prolonged courses of intravenous acyclovir 1
• Higher risk of developing herpes zoster encephalitis when immunosuppressed 2

VZV Cerebellitis

• No specific antiviral treatment is needed for isolated VZV cerebellitis, as it is usually self-limiting and resolves within 1-3 weeks 1
• The pathogenic process is thought to be immune-mediated demyelination rather than viral cytopathology 1

Common Pitfalls to Avoid

• Delay in treatment initiation: Early treatment is crucial for better outcomes
• Inadequate dosing: Using standard HSV dosing (10 mg/kg) may be suboptimal for VZV which is less sensitive to acyclovir
• Failure to consider vasculopathy: Missing the opportunity to use corticosteroids when indicated
• Premature discontinuation: Shorter courses (<14 days) may be inadequate for CNS infections
• Overlooking renal function: Acyclovir nephrotoxicity risk increases after several days of therapy

By following these guidelines, clinicians can optimize treatment outcomes for patients with herpes zoster encephalitis, reducing morbidity and mortality associated with this serious neurological complication of VZV infection.