Cataplexy

A debilitating medical condition in which a person suddenly feels weak and collapses at moments of strong emotion such as laughter, anger, fear or surprise. In so collapsing, people with cataplexy may injure themselves. Laughter and other emotions trigger a reflex in persons that can bring many of the muscles of the body to the point of collapse. The phenomenon can be measured by sending electric signals through the muscles and gauging their response. In cataplexy, what is known as the H-reflex, a neurological pathway that causes muscle contractions, virtually disappears. Cataplexy often affects people who have narcolepsy, a disorder in which there is great difficulty remaining awake during the daytime. The word "cataplexy" comes from the Greek "kata" meaning "down" + "plexis" meaning a stroke or seizure = a falling-down seizure.

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A transient attack of extreme generalized weakness, often precipitated by an emotional response, such as surprise, fear, or anger; one component of the narcolepsy quadrad. [cata- + G. plexis, a blow, stroke]

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cat·a·plexy 'kat-ə-.plek-sē n, pl -plex·ies -sēz a sudden loss of muscle control with retention of clear consciousness that follows a strong emotional stimulus (as elation, surprise, or anger) and is a characteristic symptom of narcolepsy

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n.

a sudden onset of muscle weakness that may be precipitated by excitement or emotion. There may be total loss of muscle tone, resulting in collapse, or simply jaw dropping or head nodding. It occurs in 60-90% of patients with narcolepsy.

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cat·a·plexy (katґə-plek″se) a condition in which there are abrupt attacks of muscular weakness and hypotonia triggered by an emotional stimulus such as mirth, anger, fear, or surprise. It is often associated with narcolepsy.