What is the inpatient management of encephalopathy with herpes zoster (shingles)?

Inpatient Management of Encephalopathy with Herpes Zoster (Shingles)

Intravenous acyclovir at 10 mg/kg every 8 hours for 14-21 days is the cornerstone of treatment for encephalopathy associated with herpes zoster, with immediate initiation upon clinical suspicion to reduce mortality and improve outcomes. 1, 2

Initial Management

Immediate Treatment

• Start IV acyclovir immediately upon suspicion of herpes zoster encephalitis 1, 2
  • Adult dosing: 10 mg/kg IV every 8 hours 1, 2
  • Adjust dose in patients with renal impairment 1, 3
• Do not delay treatment while waiting for diagnostic confirmation 1
• Consider empiric antibacterial coverage if bacterial meningitis cannot be excluded 2

Diagnostic Workup

• Perform lumbar puncture for CSF analysis 2, 1
  • PCR for VZV DNA (though negative result does not exclude diagnosis) 2
  • Cell count, protein, glucose
• Neuroimaging (MRI preferred over CT) 2, 1
• EEG to assess for seizure activity 2

Supportive Care

Critical Care Management

• ICU assessment for patients with declining consciousness 2, 1
• Airway protection and ventilatory support as needed 2
• Management of raised intracranial pressure 2, 1
• Optimization of cerebral perfusion pressure 2
• Correction of electrolyte imbalances 2, 1

Seizure Management

• Prophylactic anticonvulsants are not routinely recommended
• Treat clinical seizures with appropriate anticonvulsants

Monitoring and Treatment Duration

Treatment Monitoring

• Regular assessment of renal function (creatinine, BUN) 1
  • Risk of nephropathy increases after 4 days of therapy 1
• Monitor for crystalluria and adequate hydration 2
• Clinical neurological assessment daily 2

Treatment Duration

• Continue IV acyclovir for 14-21 days 2, 1
• Perform repeat lumbar puncture at treatment completion to confirm viral clearance 2, 1
• If CSF remains positive for VZV by PCR, continue acyclovir with weekly PCR until negative 2

Special Considerations

Corticosteroids

• Consider adding corticosteroids (prednisolone 60-80 mg daily for 3-5 days) due to the inflammatory nature of VZV-associated encephalitis 2
• Particularly beneficial in cases with marked cerebral edema 1

Renal Impairment

• Adjust acyclovir dosing based on creatinine clearance 1, 3
• For patients on dialysis, hemodialysis provides better acyclovir clearance than peritoneal dialysis 4
• Consider temporary switch to hemodialysis if acyclovir encephalopathy develops in peritoneal dialysis patients 4

Treatment Response

• Expect clinical improvement within 72 hours of initiating IV acyclovir 5
• Poor prognostic factors include age >30 years, low Glasgow Coma Score, and duration of symptoms >4 days before starting treatment 1, 2

When to Stop Treatment

Acyclovir can be discontinued if:

• An alternative diagnosis has been confirmed 2
• HSV/VZV PCR in CSF is negative on two occasions 24-48 hours apart, and MRI is not characteristic 2, 1
• HSV/VZV PCR in CSF is negative once >72 hours after symptom onset, with unaltered consciousness, normal MRI, and CSF white cell count <5 × 10^6/L 2

Common Pitfalls to Avoid

• Delaying treatment while waiting for diagnostic confirmation 1
• Administering incorrect acyclovir dosage 1
• Using oral acyclovir instead of IV formulation (inadequate CSF penetration) 2, 1
• Stopping treatment based on a single negative CSF PCR early in the disease course 2, 1
• Inadequate monitoring of renal function 1

Rapid initiation of appropriate antiviral therapy is crucial for improving outcomes in patients with herpes zoster encephalitis, with evidence showing dramatic responses to IV acyclovir within 72 hours of treatment initiation 5.