Résumé
A case of Kleine-Levin syndrome, with chronic severe periodic hypersomnia is described in a 17-year-old female. The first episode started when she was 15 years old. The episodes were characterized by periodic hypersomnia accompanied by hyperphagia, lasting 5 days, and repeating at 28 to 60 day intervals. The severity of hypersomnia prevented her from attending school activities. Outside the hypersomnia periods, she was asymptomatic. EEG, brain computerized tomography and brain nuclear magnetic resonance were normal; all-night polysomnography, Multiple Sleep Latency Test (MSLT) and Epworth Sleepiness Scale (ESS) were within normal limits. During the period of hypersomnolence, polysomnography showed short sleep latency and short REM latency. MSLT mean sleep latency was 1.8 min; and REM period was present in one subtest; the ESS was markedly elevated.