What are the management guidelines for acute encephalitis syndrome?

Management of Acute Encephalitis Syndrome

Patients with suspected acute encephalitis require immediate neurological specialist assessment within 24 hours and should receive empiric intravenous aciclovir while awaiting diagnostic confirmation, as this dramatically improves outcomes for herpes simplex virus encephalitis, the most important treatable cause. 1, 2

Immediate Assessment and Stabilization

Critical Care Triage

• Patients with falling level of consciousness require urgent ICU assessment for airway protection, ventilatory support, management of raised intracranial pressure, optimization of cerebral perfusion pressure, and correction of electrolyte imbalances 1, 3
• Equipment necessary to maintain a patent airway must be immediately available, particularly if benzodiazepines are used for seizure management 4
• Patients should be managed in neurological wards, high dependency units, or intensive care units depending on severity 5, 1

Multidisciplinary Team Involvement

• Acute care requires input from neurologists, infectious disease physicians, virologists, microbiologists, neurophysiologists, neuroradiologists, and intensive care staff 5
• Close monitoring in a quiet environment is essential, though routine isolation is not required 5

Diagnostic Workup

Neuroimaging

• MRI is the imaging modality of choice and should be obtained within 48 hours, detecting early cerebral changes in approximately 90% of cases versus only 25% sensitivity for CT 1
• Neuroimaging access is essential for proper diagnosis with Level A evidence strength 1

Cerebrospinal Fluid Analysis

• CSF analysis is critical for confirming diagnosis, with PCR results ideally available within 24-48 hours of lumbar puncture 1, 2
• Lumbar puncture should not be delayed unless strict contraindications exist, even if neuroimaging is not immediately available 2
• CSF should be analyzed for protein and glucose contents, cellular analysis, and pathogen identification by PCR (Level A recommendation) and serology (Level B recommendation) 2

Electroencephalography

• EEG is abnormal in >80% of encephalitis cases but need not be performed routinely in all patients 1
• Obtain EEG when distinguishing psychiatric versus organic causes in patients with mildly altered behavior, or when subtle motor or non-convulsive seizures are suspected 1

Special Populations: Returning Travelers

• Patients returning from malaria-endemic areas require rapid blood malaria antigen tests and ideally three thick and thin blood films examined for malaria parasites 5, 1
• Thrombocytopenia or malaria pigment in neutrophils and monocytes may indicate malaria even if films are negative 5
• If cerebral malaria seems likely with delayed film results, initiate anti-malarial treatment immediately and obtain specialist advice 5, 1

Empiric and Specific Treatment

Herpes Simplex Virus Encephalitis

• Aciclovir is the evidence-based treatment for HSV encephalitis (Level A recommendation) and should be started empirically in all suspected cases 2, 6
• For immunocompromised patients, treat with intravenous aciclovir 10 mg/kg three times daily for at least 21 days, then reassess with CSF PCR 5
• Consider long-term oral treatment until CD4 count >200 × 10⁶/L in HIV patients 5

Other Viral Causes

• Aciclovir may be effective for varicella-zoster virus encephalitis (Class IV evidence) 2
• Ganciclovir and foscarnet for cytomegalovirus encephalitis (Class IV evidence) 2
• Pleconaril for enterovirus encephalitis (Class IV evidence) 2

Parasitic Causes

• Toxoplasma gondii: treat with pyrimethamine plus either sulfadiazine or clindamycin (Level A-I) 1
• Plasmodium falciparum (cerebral malaria): treat with quinine, quinidine, or artemether (Level A-III) 1
• Exchange transfusion is recommended for ≥10% parasitemia 1
• Corticosteroids are NOT recommended for cerebral malaria 1

Autoimmune Encephalitis

• Acute Disseminated Encephalomyelitis (ADEM): treat with high-dose corticosteroids as first-line (Level B-III) 1
• Alternative treatments include plasma exchange or intravenous immunoglobulin 1
• Corticosteroids are also indicated for VZV with vasculitis and Baylisascaris procyonis 1

Status Epilepticus Management

• For status epilepticus, administer lorazepam 4 mg IV slowly (2 mg/min) for patients ≥18 years 4
• If seizures continue after 10-15 minutes, give an additional 4 mg IV dose slowly 4
• Maintain unobstructed airway, monitor vital signs, and have artificial ventilation equipment immediately available 4
• Status epilepticus requires more than anticonvulsant administration—immediately seek and correct metabolic causes like hypoglycemia or hyponatremia 4

Adjunctive Therapies

Corticosteroid Use

• Corticosteroids are NOT generally effective for acute viral encephalitis and their use is controversial 2
• Specific indications: ADEM, VZV with vasculitis, and Baylisascaris procyonis 1

Surgical Intervention

• Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management 2
• Brain biopsy should be reserved only for unusual and diagnostically difficult cases 2, 7

Discharge Planning and Rehabilitation

Follow-up Requirements

• Patients must not be discharged without either a definite or suspected diagnosis 5, 1
• Arrangements for outpatient follow-up and plans for ongoing therapy and rehabilitation should be formulated at a discharge meeting, including at least one follow-up appointment 5, 1

Rehabilitation Access

• All patients irrespective of age should have access to assessment for rehabilitation 5, 1, 3
• Sequelae may not be immediately apparent at discharge—anxiety, depression, and obsessive behaviors often emerge subsequently 5
• A comprehensive approach requires neuropsychology, neuropsychiatry, speech and language therapy, neuro-physiotherapy, and occupational therapy 5
• Access to specialist brain injury rehabilitation services is key to recovery 5

Common Pitfalls and Caveats

• Never delay aciclovir while awaiting diagnostic confirmation—HSV encephalitis outcomes are dramatically improved with early treatment 2, 6
• Do not discharge patients without follow-up planning, as 33% of encephalitis patients have been discharged without outpatient follow-up, yet 96% report ongoing complications 5
• Lumbar puncture should not be routinely delayed for neuroimaging unless strict contraindications exist 2
• Brain biopsy is rarely needed and should be reserved for diagnostically difficult cases 2, 7
• Consult with a neurologist if a patient fails to respond or regain consciousness 4