A menstruation-linked periodic hypersomnia. Kleine-Levin syndrome or new clinical entity?

A 13-year-old girl showed periodic episodes of somnolence without megaphagia recurring in association with each menstruation. During somnolent episodes total sleep time averaged 14 hours and 19 minutes per 24 hours. The level of performance evaluated by means of the Wilkinson Addition Test was significantly impaired. There was an abnormal increase of 5-hydroxyindolacetic acid in the cerebrospinal fluid after probenecid test, suggesting an increase of the turnover of 5-hydroxytryptamine during periodic hypersomnia. Investigation of the menstrual cycle failed to document any striking hormonal abnormality. Nevertheless, the close relationship between the episodes of hypersomnia and the end of the menstrual cycle led us to hypothesize a role of progesterone and to try a hormonal type of treatment that is thus far successful.