Epidemiology and outcomes of acute encephalitis

This review seeks to describe recent advances in the epidemiology, outcomes, and prognostic factors in acute encephalitis.

Infectious causes continue to account for the largest proportion of encephalitis cases in which a cause is identified, although autoimmune causes are increasingly recognized. Type-A gamma-aminobutyric acid (GABAa) receptor antibodies have been recently identified in encephalitis with refractory seizures, whereas the roles of antibodies to the glycine receptor and dipeptidyl peptidase-like protein 6 have been defined in progressive encephalomyelitis with rigidity and myoclonus. Recent findings in the US cases of encephalomyelitis presenting with acute flaccid paralysis raise the possibility that enterovirus D68, a common respiratory pathogen, may cause central nervous system disease. Mortality from acute encephalitis occurs in about 10% of cases, with a large proportion of survivors suffering from cognitive or physical disability. In addition to delay in institution of appropriate antiviral or immune therapy, several potentially reversible factors associated with poor prognosis have been identified, including cerebral edema, status epilepticus, and thrombocytopenia.

Encephalitis imposes a significant worldwide health burden and is associated with poor outcomes. Supportive treatment and early institution of therapy may improve outcomes. Careful neurocognitive assessment of survivors of encephalitis is needed to better define long-term outcomes.