Abstract
Encephalitis lethargica was an enigma throughout its one and only epidemic. All those who have concerned themselves with this disease have been impressed, above all, by its strangeness — no fiction author would have had the temerity to invent a disorder of such incredible clinical diversity and puzzling behavior — and then the mystery was deepened, and its solution perhaps rendered inaccessible, by its unexpected disappearance. The influenza pandemic of 1918/19 killed many more people, and polio made an especially terrifying impression as a crippling disorder of childhood, but EL retains a special place in the history of brain disease because of its peculiar acute face, the fascinating horror of its intermediate and chronic stages, and the uncertainty of both its origins and its withdrawal.