Encephalitis: Recognizing the Symptom Spectrum and the Urgency of Immediate Care

Common Manifestations

• Prodrome: Fever, headache, malaise, myalgia—often indistinguishable from a viral syndrome.
• Altered Mental Status: Confusion, lethargy, agitation, personality changes, or progression to coma.
• Focal Neurologic Deficits: Hemiparesis, aphasia, cranial nerve palsies, ataxia.
• Seizures: Focal or generalized; may become refractory (status epilepticus).
• Meningeal Signs: Nuchal rigidity, photophobia, positive Kernig/Brudzinski signs (indicating meningoencephalitis).
• Autonomic Instability: Temperature dysregulation, blood pressure lability.
• Sensory Disturbances: Visual or hearing changes.

Major Etiologies

• Viral: HSV-1 (most common sporadic), VZV, enteroviruses, arboviruses (West Nile, Japanese encephalitis, Zika).
• Autoimmune: Anti-NMDA receptor, LGI1, CASPR2, GABA_BR encephalitis.
• Bacterial/Fungal/Parasitic: Tuberculosis, neurosyphilis, Lyme neuroborreliosis, cryptococcal, toxoplasma.
• Paraneoplastic: Associated with underlying malignancy.

Critical Action: Time Is Brain

Any encephalopathy accompanied by fever, seizure, or focal neurologic sign constitutes a medical emergency. Immediate workup includes brain MRI, lumbar puncture with broad PCR panel, EEG, and autoimmune antibody testing. Empiric acyclovir plus antibiotics and steroids should be started before confirmatory results if clinical suspicion is high. Mortality ranges from 10–30% even with treatment; delays significantly worsen outcomes.