Twenty-four-hour sleep–wake monitoring in narcolepsy: comparison with MSLT

Abstract

The diagnosis of narcolepsy (ICSD-2) should be confirmed by a whole night polysomnographyic recording followed by a Multiple Sleep Latency Test (MSLT). MSLT is designed to provide information about the sleep tendency when the patients lie down. However, narcoleptics fall asleep during daily life under the variety of conditions. A 24-h monitoring is superior to MSLT in the identification of sleepiness during the day. The objective of this study was to detect SOREMPs by 24-h ambulatory monitoring and diagnose more precisely. Ten patients with narcolepsy (6 women and 4 men; age range, 8–64 years) enrolled in this study: 5 narcoleptics with cataplexy and 5 narcoleptics without cataplexy. The sleep-wake monitoring procedure as follows: (1) 24-h sleep-wake monitoring, after that (2) nocturnal sleep monitoring from 22:00 to 7:00, followed the next day by 3) MSLT at 10:00, 12:00, 14:00, and 16:00. Patients were instructed to maintain wakefulness in their rooms, reading books, listening to the radio. Sleep stages were visually scored for 20-s epochs according to Rechtschahffen and Kales criteria. 1) 24-h monitoring: Eight out of ten narcoleptics (5 patients: narcolepsy with cataplexy) showed SOREMPs on nocturnal recording. During daytime, SOREMPs were detected in another 8 out of 10 narcoleptics, although the patients fell asleep sitting in their chairs. Two or more SOREMPs were recognized during 24-h monitoring in 80% narcoleptics with narcolepsy. The amount of daytime sleep was 123.7 < 104.7 min and REM sleep was 15.3 < 9.7 min. During nighttime, average total sleep time was 486.4 < 59.5 min and REM sleep was 102.7 < 34.3 min. (2) MSLT: The number of sleep onset REM periods was 2.9 < 0.9. On the night before the MSLT, average total sleep. Hishikawa et al. reported that sleep of narcoleptics was markedly influenced by the posture in which they fell asleep. In our study, narcoleptics were instructed to maintain wakefullness. Although narcoleptics tended to get deprivation of REM sleep under these conditions, SOREMPs were detected in 80% of narcoleptics. Twenty-four-hour sleep-wake monitoring appears to be a useful procedure for diagnosis of narcolepsy. Syouji Yasuyo.