What is the management of viral encephalopathy?

Management of Viral Encephalopathy: Etiology, Diagnosis, and Treatment

Intravenous aciclovir (10 mg/kg three times daily) should be started immediately if viral encephalitis is suspected, and continued for 14-21 days in cases of confirmed HSV encephalitis. 1

Etiology

• Viral encephalitis is most commonly caused by herpes simplex virus (HSV), varicella-zoster virus (VZV), enteroviruses, and in specific regions, arboviruses 1
• Other causes include measles virus, cytomegalovirus, human herpes virus 6, and JC/BK virus (particularly in immunocompromised patients) 1
• Non-viral causes that may mimic viral encephalitis include bacterial infections (tuberculosis, syphilis, Lyme disease), fungal infections (cryptococcosis), parasitic infections (toxoplasmosis), and autoimmune conditions 1

Diagnosis

Clinical Features

• Altered consciousness, confusion, behavioral changes, new seizures, or focal neurological signs should raise suspicion of encephalitis 1
• Differentiate encephalitis (inflammation of brain parenchyma) from meningitis (inflammation of meninges) and encephalopathy (metabolic or toxic causes) 2

Diagnostic Workup

• Lumbar puncture (LP) is essential for diagnosis - check cell count, protein, glucose, and perform PCR for HSV and other viruses 1, 2
• MRI is more sensitive than CT for detecting encephalitis-related changes and should be performed when available 1, 2
• EEG may help identify subclinical seizures and characteristic patterns in certain types of encephalitis 1
• If there will be delays in obtaining LP results or if the patient is rapidly deteriorating, empiric treatment should be started 1

Management

Antiviral Therapy

• For HSV encephalitis:

  • Intravenous aciclovir 10 mg/kg every 8 hours for adults with normal renal function 1, 3
  • For children 3 months-12 years: 500mg/m² every 8 hours 1
  • For children >12 years: 10mg/kg every 8 hours 1
  • Continue treatment for 14-21 days 1
  • Perform repeat LP at the end of treatment to confirm CSF is negative for HSV by PCR 1, 4
  • If CSF remains positive, continue aciclovir with weekly PCR until negative 1

• For VZV encephalitis:

  • Intravenous aciclovir 10-15 mg/kg three times daily 1
  • Consider corticosteroids if there is evidence of vasculopathy (stroke) 1

• For enterovirus encephalitis:

  • No specific treatment is recommended routinely 1
  • In severe cases, consider pleconaril (if available) or intravenous immunoglobulin 1

When to Stop Empiric Aciclovir

• If an alternative diagnosis has been made 4
• If HSV PCR in CSF is negative on two occasions 24-48 hours apart, and MRI is not characteristic for HSV encephalitis 4
• If HSV PCR in CSF is negative once >72 hours after symptom onset, with normal consciousness, normal MRI, and CSF white cell count <5×10⁶/L 4

Supportive Care

• Patients with falling level of consciousness require urgent ICU assessment for airway protection, ventilatory support, and management of raised intracranial pressure 1
• Monitor and correct electrolyte imbalances 1
• Provide seizure control as needed 1

Special Considerations

Immunocompromised Patients

• May present with atypical features and broader range of causative pathogens 1
• May require prolonged antiviral therapy, particularly for VZV encephalitis 1

Returning Travelers

• Consider malaria in patients returning from endemic areas - obtain rapid blood malaria antigen tests and blood films 1
• If cerebral malaria seems likely and there will be delay in obtaining results, consider empiric anti-malarial treatment 1

Complications and Follow-up

• Mortality for untreated HSV encephalitis exceeds 70%, reduced to 20-30% with aciclovir treatment 1, 3
• Common sequelae include cognitive impairment, behavioral changes, epilepsy, and focal neurological deficits 1, 5
• All patients should have outpatient follow-up arranged and access to rehabilitation services 1

Common Pitfalls

• Failing to distinguish between viral meningitis (where oral aciclovir is not indicated) and HSV encephalitis (where intravenous aciclovir is essential) 4, 2
• Delaying aciclovir treatment beyond 48 hours after admission, which is associated with worse outcomes 1, 3
• Inadequate dose adjustment in patients with renal impairment, leading to nephrotoxicity 1, 3
• Premature cessation of diagnostic workup after starting empiric antimicrobials 1, 2
• Inadequate monitoring for aciclovir-related nephropathy, which can affect up to 20% of patients after 4 days of IV therapy 1, 3