What is the management approach for a patient with encephalitis without altered consciousness?

Management of Encephalitis Without Altered Consciousness

Patients with suspected encephalitis who lack altered consciousness should still receive immediate empiric intravenous acyclovir 10 mg/kg every 8 hours while undergoing urgent diagnostic workup, as delays beyond 48 hours significantly worsen outcomes even in less severe presentations. 1, 2

Immediate Management Actions

Start empiric acyclovir immediately while awaiting diagnostic confirmation, even in patients without altered consciousness, as early treatment is critical for preventing progression and improving outcomes. 1, 2

• Administer acyclovir 10 mg/kg IV every 8 hours in adults and adolescents ≥12 years 1, 3
• Ensure adequate hydration to prevent acyclovir-induced nephropathy, which occurs in up to 20% of patients typically after 4 days of IV therapy 1
• Monitor renal function throughout treatment and adjust dosing for impaired renal function 4, 3

Urgent Specialist Assessment and Diagnostic Workup

Obtain neurological specialist consultation within 24 hours of presentation, as encephalitis can deteriorate rapidly even when initially presenting without altered consciousness. 1, 2

Neuroimaging

• MRI is the imaging modality of choice and must be obtained within 48 hours, detecting early cerebral changes in approximately 90% of cases versus only 25% sensitivity for CT 2
• Arrange imaging under general anesthesia if needed 4, 1

Lumbar Puncture and CSF Analysis

• Perform lumbar puncture urgently with CSF studies including: 1, 2
  • Opening pressure
  • CSF and serum glucose
  • CSF protein
  • Microbiology culture and sensitivity
  • Virology PCR (especially HSV, VZV, enteroviruses)
  • Lactate
• CSF PCR results should be available within 24-48 hours 4, 1

Electroencephalography

• Obtain EEG when distinguishing psychiatric versus organic causes in patients with mildly altered behavior, or when subtle motor or non-convulsive seizures are suspected (abnormal in >80% of encephalitis cases) 2

Etiology-Specific Treatment Duration

Herpes Simplex Virus (HSV) Encephalitis

• Continue acyclovir 10 mg/kg IV every 8 hours for 14-21 days in confirmed HSV encephalitis 1, 3
• Consider repeating lumbar puncture at end of treatment to confirm CSF is negative for HSV by PCR 1

Varicella Zoster Virus (VZV) Encephalitis

• Treat with acyclovir 10-15 mg/kg IV three times daily for 7-14 days 4, 1
• Consider adding corticosteroids (e.g., prednisolone 60-80 mg daily for 3-5 days) due to the inflammatory nature of VZV CNS disease, particularly if vasculitic component is present 4

Enterovirus Encephalitis

• No specific antiviral treatment is recommended for enterovirus encephalitis 4
• In severe disease, consider pleconaril (if available) or intravenous immunoglobulin, though evidence is limited 4

Monitoring and Seizure Management

Close monitoring is essential even without altered consciousness, as patients remain at risk for seizures, behavioral disturbances, and clinical deterioration. 4

If Seizures Develop

• IV valproate 20-30 mg/kg loading dose achieves 88% seizure cessation within 20 minutes without associated hypotension 2, 5
• Alternative: Levetiracetam 30-60 mg/kg/day demonstrates 73% seizure cessation rate 2, 5
• Phenytoin 18-20 mg/kg IV has lower efficacy (56%) and causes hypotension in 12% of cases 2, 5

Consider Autoimmune Encephalitis

Screen for antibody-mediated encephalitis in patients with subacute presentation, particularly those with intractable seizures, orofacial dyskinesia, choreoathetosis, or hyponatremia. 2, 5

• Consider high-dose corticosteroids as first-line treatment for Acute Disseminated Encephalomyelitis (ADEM) 1, 2
• For NMDAR or VGKC-complex antibody-associated encephalitis, consider rituximab as second-line immunotherapy 2
• Screen for neoplasm in all patients with VGKC complex or NMDA receptor antibody-associated encephalitis 5

Transfer Criteria

Transfer to a neurological unit should occur within 24 hours if: 4

• Diagnosis is not rapidly established
• Patient fails to improve with therapy
• Access to specialized neuroimaging, EEG, or ICU capabilities is needed

Common Pitfalls to Avoid

• Never delay acyclovir beyond 48 hours after hospital admission, as this significantly worsens outcomes 1
• Do not withhold acyclovir based on absence of altered consciousness alone, as encephalitis can progress rapidly 1, 2
• Avoid inadequate hydration during acyclovir treatment, which increases nephropathy risk 1
• Do not miss bacterial meningitis—consider both diagnoses and add appropriate antibacterial coverage if bacterial infection cannot be excluded 1
• Avoid rapid or bolus IV injection of acyclovir; must be infused over 1 hour at constant rate 3
• Never administer acyclovir intramuscularly or subcutaneously 3

Follow-Up and Rehabilitation

Arrange outpatient follow-up and rehabilitation assessment at discharge, as sequelae may not be immediately apparent and commonly include anxiety, depression, and cognitive deficits. 2