A person laughs to a joke, and then suddenly loses tone of all his muscles. Most probable diagnosis of this condition is?

ANSWER: (A) CataplexyREF: Kaplan & Sadock's Synopsis of Psychiatry 10th Edition Page 274, 760 Cataplexy:Temporary sudden loss of muscle tone, causing weakness and immobilization; can be precipitated by a variety of emotional states and is often followed by sleep. Commonly seen in narcolepsy.Catalepsy:Condition in which persons maintain the body position into which they are placed; observed in severe cases of catatonic schizophrenia. Also called waxy flexibility and cerea flexibilitas. See also command automatism.Cathexis:In psychoanalysis, a conscious or unconscious investment of psychic energy in an idea, concept, object, or person