APHP Nord, Hôpital Bichat, Paris, France

The Spectrum of Acute Encephalitis : A Clinical Perspective.

Invited by Jean-Pierre Levraud

Encephalitis is a condition of inflammation of the brain parenchyma, mainly of infectious or autoimmune origin. It is a severe neurological syndrome associated with encephalopathy, seizures, focal deficits, neurological disability, and death. Large multicenter studies conducted in the adult population improved current knowledge on the epidemiology and outcomes of acute encephalitis. Viral causes account for the most significant proportion, but autoimmune causes have been increasingly recognized in the last decade. A multimodal diagnostic workup (including CSF analysis, brain MRI, EEG, and serum studies) is mandatory for diagnosis. New diagnostic methods, including multiplex PCR and next-generation sequencing techniques, allow for a faster differential diagnosis of infectious causes that may require specific antimicrobial therapy. Observational data suggest that early immunotherapy is associated with better outcomes in patients with autoimmune encephalitis. In severe cases requiring care in the intensive care unit, symptomatic measures for preventing complications are mandatory, with particular attention to seizures, cerebral edema, and dysautonomia. Large multicenter studies combining clinical, electrophysiological, and neuroimaging data are urgently needed to improve current knowledge on care pathways, long-term outcomes, and prognostication.