Clinical and Polysomnographic Features of Kleine-Levin Syndrome: Case Series.

Kleine-Levin Syndrome (KLS) is a rare disorder characterized intermittent hypersomnia, hyperphagia, hypersexuality, abnormal behaviors, and confusion. Patients are asymptomatic between episodes. The aim of this case series study was to determine the clinical features of patients with KLS and to compare the polysomnography (PSG) findings between symptomatic and asymptomatic periods. We compared the results of PSG investigations performed in symptomatic and asymptomatic periods in six patients diagnosed with KLS at Gulhane Military Medical Faculty Sleep Research Center between 1998 and 2005. The age at onset of KLS was approximately 18 years, the diagnosis delayed 2.67 years, hypersomnia episodes lasted approximately 11.5 days, until the correct diagnosis, the patients had experienced on average 5 episodes. Total sleep time in KLS patients during symptomatic period and stage 2 sleep percent was higher than in asymptomatic period. REM latency was shorter and stage 3 and REM percent was lower in asymptomatic period. The clinical features including the age of onset and episode duration are compatible with those from the previous studies. It was observed that the sleep architecture during symptomatic period was different from that in asymptomatic period.