Test-Retest Reliability of the Multiple Sleep Latency Test in Narcolepsy without Cataplexy and Idiopathic Hypersomnia

TLDR

The multiple sleep latency test (MSLT) is the sole tool used to differentiate narcolepsy without cataplexy from idiopathic hypersomnia, highlighting a need for alternative diagnostic methods. This study aimed to determine the test‑retest reliability of the MSLT in patients with central nervous system hypersomnias by retrospectively analyzing two diagnostic MSLTs per patient. Thirty‑six patients (58 % women, mean age 34 yr) who underwent two MSLTs separated by a mean interval of 4.2 ± 3.8 years were evaluated for correlations between mean sleep latencies and for demographic or clinical factors that might influence diagnostic stability. The MSLT showed poor test‑retest reliability, with no significant correlation between mean sleep latencies (r = 0.17, p = 0.31) and a 53 % rate of diagnostic change, driven mainly by differences in mean latency or sleep‑onset REM periods, and only a history of hypnagogic.

Abstract

Differentiation of narcolepsy without cataplexy from idiopathic hypersomnia relies entirely upon the multiple sleep latency test (MSLT). However, the test-retest reliability for these central nervous system hypersomnias has never been determined.Patients with narcolepsy without cataplexy, idiopathic hypersomnia, and physiologic hypersomnia who underwent two diagnostic multiple sleep latency tests were identified retrospectively. Correlations between the mean sleep latencies on the two studies were evaluated, and we probed for demographic and clinical features associated with reproducibility versus change in diagnosis.Thirty-six patients (58% women, mean age 34 years) were included. Inter -test interval was 4.2 ± 3.8 years (range 2.5 months to 16.9 years). Mean sleep latencies on the first and second tests were 5.5 (± 3.7 SD) and 7.3 (± 3.9) minutes, respectively, with no significant correlation (r = 0.17, p = 0.31). A change in diagnosis occurred in 53% of patients, and was accounted for by a difference in the mean sleep latency (N = 15, 42%) or the number of sleep onset REM periods (N = 11, 31%). The only feature predictive of a diagnosis change was a history of hypnagogic or hypnopompic hallucinations.The multiple sleep latency test demonstrates poor test-retest reliability in a clinical population of patients with central nervous system hypersomnia evaluated in a tertiary referral center. Alternative diagnostic tools are needed.