What is "cataplexy"

Cataplexy \Cat"a*plex`y\, n. [Gr. ? amazement: cf. Apoplexy.] (Med.) A morbid condition caused by an overwhelming shock or extreme fear and marked by rigidity of the muscles. -- Cat`a*plec"tic, a.

"the state of an animal when it is feigning death," 1883, from German kataplexie, from Greek kataplexis "stupefaction, amazement, consternation," from kataplessein "to strike down" (with fear, etc.), from kata- "down" (see cata-) + plessein "to strike, hit," from PIE *plak- (2) "to strike" (see plague (n.)). Related: Cataplectic.

n. (context medicine English) An abrupt loss of muscle tone, sometimes associated with narcolepsy.

Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror. It is the cardinal symptom of narcolepsy with cataplexy affecting roughly 70% of people who have narcolepsy, and is caused by an autoimmune destruction of the neurotransmitter hypocretin (also called orexin), which regulates arousal and wakefulness. Cataplexy without narcolepsy is rare and the cause is unknown.

The term cataplexy originates from the Greek κατά (kata, meaning "down"), and πλῆξις (plēxis, meaning "stroke").