0613 Multimodal Hypersomnolence Assessment Substantially Increases Objective Identification of Hypersomnolence in Patients Referred for Multiple Sleep Latency Testing

In the present paper, the assessment of sleepiness in general and the status quo in “Deutsche Gesellschaft für Schlafforschung und Schlafmedizin” (DGSM; German Sleep Society)-accredited sleep laboratories are examined. The first question deals with the definition of sleepiness; the second question refers to different methods of assessing sleepiness with a special focus on the Multiple Sleep Latency Test (MSLT), which is considered the gold standard to measure sleepiness. The main outcomes are mean sleep latency and the number of sleep onset REM periods (SOREMPs). Two or more SOREMPs are indicative for the diagnosis of narcolepsy; therefore, correct scoring and interpretation are relevant. The third question is related to the implementation of the MSLT in DGSM-accredited laboratories and whether the MSLT is performed in compliance with the latest guidelines. A questionnaire survey on implementation of the MSLT revealed that 82% apply the MSLT. Questions on the protocol and interpretation of MSLTs indicated that the practice is inhomogeneous. Results of a scoring study, in which DGSM-accredited laboratories were asked to score in total 19 MSLT sessions of 4 different patients, indicated that not only the performance of MSLTs but also evaluation varies across laboratories. For the present article, we focus on the results of the REM sleep parameters scored and reported by the laboratories, and discuss possible reasons for the relatively high heterogeneity between the laboratories, and in some cases differences between the scoring of REM and the reported REM latency and/or SOREMPs. While the scoring of REM per se seems difficult and might not be adequately detected, there is no generally applicable definition of SOREMPs. In several guidelines an observation period of 15 min after the onset of sleep is recommended, while in the German Leitlinie S3 10 min is proposed. Since the length of the recording period has consequences for the definition of SOREMPs, the apparently small difference of 5 min can have detrimental effects on the diagnosis of narcolepsy.