Acute encephalitis is an inflammatory brain disease with a complex differential diagnosis associated with appreciable morbidity, mortality, and costs. Infectious agents, particularly viruses, were traditionally considered the predominant causes. The discovery of neuronal cell-surface autoantibodies (NSAbs) has helped identify a subgroup of patients with encephalitis who often respond well to immunotherapy. Autoantibodies were not mentioned in a 2007 retrospective study on the causes of acu...