Encephalitis lethargica
atypical form of encephalitis
Encephalitis lethargica (EL) is an atypical form of encephalitis. Also known as "von Economo Encephalitis", "sleeping sickness" or "sleepy sickness" (distinct from tsetse fly–transmitted sleeping sickness), it was first described in 1917 by neurologist Constantin von Economo and pathologist Jean-René Cruchet. The disease attacks the brain, leaving some victims in a statue-like condition, speechless and motionless. Between 1915 and 1926, an epidemic of encephalitis lethargica spread around the world. The exact number of people infected is unknown, but it is estimated that more than one million people contracted the disease during the epidemic, which directly caused more than 500,000 deaths. Most of those who survived never recovered their pre-morbid vigor.
Signs and symptoms
Encephalitis lethargica is characterized by high fever, sore throat, headache, lethargy, double vision, delayed physical and mental response, sleep inversion and catatonia. In severe cases, patients may enter a coma-like state (akinetic mutism). Patients may also experience abnormal eye movements ("oculogyric crises"), Parkinsonism, upper body weakness, muscular pains, tremors, neck rigidity, and behavioral changes including psychosis. Klazomania, a vocal tic involving compulsive screaming, is sometimes present.
“Encephalitis lethargica” enters the record as atypical form of encephalitis. Crown Archives preserves that source wording while asking what Encephalitis, lethargica and atypical can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 25, 2026. The linked authority identifier is Q1369020. The Library of Congress control number is sh85042976. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1917, 1915 and 1926.
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This entry incorporates text from “Encephalitis lethargica” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.