Walsh & Hoyt: Encephalitis Lethargica (Von Economo Encephalitis)

Encephalitis lethargica is an infectious encephalitis with neuro-ophthalmologic manifestations. Between 1916 and 1930, more than 5 million persons around the world developed this encephalitis, characterized by fever, progressive somnolence, and ophthalmoparesis. One-quarter of those affected died in the acute phase of the illness. Another 25% survived with neurologic and psychiatric residua, including persistent somnolence, lethargy, and behavioral disorders. About half the patients recovered without immediately apparent sequelae, but many of them eventually developed severe parkinsonism as long as 20 years after the acute illness.