Can a patient with Varicella-Zoster Virus (VZV) encephalitis and facial involvement, who is improving in cognition but still disoriented to time while on intravenous (IV) acyclovir, be switched to oral valacyclovir (valacyclovir)?

Management of VZV Encephalitis: IV to Oral Transition

For a patient with VZV encephalitis who is improving in cognition but still disoriented to time, intravenous acyclovir should be continued for the full recommended 14-21 day course rather than switching to oral valacyclovir at this stage of treatment.

Treatment Duration and Route for VZV Encephalitis

• Guidelines from the Association of British Neurologists and British Infection Association recommend intravenous acyclovir 10-15 mg/kg three times daily for VZV encephalitis for up to 14 days 1
• The full course of IV treatment is particularly important for encephalitis (as opposed to meningitis) due to the higher morbidity and mortality associated with brain parenchymal involvement
• Persistent disorientation to time indicates ongoing neurological dysfunction, suggesting active disease requiring continued optimal therapy

Why Oral Switch Is Not Recommended at This Time

Factors Against Switching to Oral Therapy:

• The patient still shows signs of encephalopathy (disorientation to time)
• Guidelines specifically state that for HSV and VZV encephalitis, IV acyclovir should be continued for the full 14-21 day course 1
• Oral acyclovir does not achieve adequate levels in the CSF 1
• While valacyclovir has better bioavailability than oral acyclovir, it is not FDA-approved for VZV encephalitis treatment

Potential Exceptions (Not Applicable to This Case):

• Oral valacyclovir has been used in pediatric practice only when maintaining IV access has proven difficult 1
• For HSV-2 meningitis (not encephalitis), CDC suggests IV acyclovir until resolution of fever and headache, followed by oral valacyclovir to complete a 14-day course 2

Monitoring and Assessment

• Monitor renal function regularly as acyclovir can cause nephropathy in up to 20% of patients after 4 days of IV therapy 1
• Maintain adequate hydration to reduce the risk of crystalluria and renal impairment
• Consider repeat CSF examination at the end of treatment (14-21 days) to confirm viral clearance by PCR 1
• If CSF remains positive for VZV by PCR at the end of treatment, continue IV acyclovir with weekly PCR until negative 1

Special Considerations

• If the patient has a vasculitic component to their VZV encephalitis, consider adding a short course of corticosteroids 1
• For immunocompromised patients, a prolonged course of IV acyclovir may be needed 1
• Adjust acyclovir dosage in patients with impaired renal function 1

When Oral Therapy Might Be Considered

Oral therapy with valacyclovir might only be considered if:

• The patient has completed at least 14 days of IV acyclovir
• Cognitive function has fully normalized
• CSF PCR is negative for VZV
• Maintaining IV access has become problematic

In this case, with persistent disorientation, the standard of care remains completion of the full IV acyclovir course to ensure optimal neurological outcomes and prevent relapse.