Gelastic epilepsy.

A case of retinitis pigmentosa with laughing epilepsy is described. Stereotyped repetitive episodes of limb movement, rigidity, and cackling laughter responding to diazepam are recorded. One episode is presented as gelastic status epilepticus and the clinical and EEG features are reported. Features of gelastic epilepsy are discussed and briefly compared with other laughing disorders. A short history of the condition is accompanied by a relevant review of the literature. The possible importance of hypothalamic lesions in laughing epilepsy is discussed and the absence of consistent EEG findings is noted.