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

Abstract

conducted within three weeks of each other.11 Inter-test intervals are generally much longer in clinical practice, and in that case the stability of MSLT features has not been established. We therefore evaluated the test-retest reliability of the MSLT in a clinic population of patients with narcolepsy without cataplexy and idiopathic hypersomnia. METHODS Patient SelectionPatients with a clinical syndrome consistent with a CNS hypersomnia (i.e., reports of problematic, excessive daytime sleepiness persisting ≥ 3 months despite adequate or supra-normal habitual sleep durations, not explained by other causes of daytime sleepiness) who had undergone 2 MSLTs were identiStudy Objectives: 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. Methods: Patients with narcolepsy without cataplexy, idiopathic hypersomnia, and physiologic hypersomnia who underwent two diagnostic multiple sleep latency tests were identifi ed 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. Results: 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 fi rst and second tests were 5.5 (± 3.7 SD) and 7.3 (± 3.9) minutes, respectively, with no signifi cant 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. Conclusions S C I E N T I F I C I N V E S T I G A T I O N ST he central nervous system (CNS) hypersomnias manifest as excessive daytime sleepiness with or without prolonged nocturnal sleep in the absence of demonstrable nocturnal sleep pathology or insuffi cient sleep. They include the entities of narcolepsy with and without cataplexy and idiopathic hypersomnia. Narcolepsy with cataplexy is a chronic disease characterized by short latencies to both sleep and REM sleep on daytime nap opportunities during the multiple sleep latency test (MSLT) and is caused by immunogenetically mediated loss of hypocretin.1 Cataplexy is a clinical feature highly specifi c to hypocretin-defi cient narcolepsy, although is not always evident near the onset of sleepiness. The remaining CNS hypersomnias begin at a similar age, are much less likely to be associated with hypocretin defi ciency, 1-4 and lack a pathognomonic sign or symptom. 5,6 They have many features in common, including hallucinations and sleep paralysis, 1,4 unrefreshing naps, 7,8 sleep drunkenness, 1,7,8 and prolonged nocturnal sleep. [8][9][10] Therefore, differenti...

Urine Toxicology Screen in Multiple Sleep Latency Test: The Correlation of Positive Tetrahydrocannabinol, Drug Negative Patients, and Narcolepsy

“…The problems inherent are highlighted by a recent paper assessing the test-retest variability in MSLT findings and diagnosis in adults with hypersomnia. 12 The authors found a change in diagnostic category between cataplexy, idiopathic hypersomnia, and normal occurring in 53% of adults based on MSLT findings. Because of the recent movement towards decriminalization and legalization of marijuana in the USA, with recreational marijuana laws now approved in two states (Colorado and Washington) and medicinal/decriminalized marijuana laws approved in 20 states, 13 awareness of the potential effects of marijuana use on MSLT findings seems important to address, with future studies needed.…”

Wide implications of a trial on pitolisant for cataplexy

“…Still, the diagnostic value of standard MSLT is not optimal as shift work and chronic sleep deprivation can produce similar findings, 5,6 and test-retest reliability of MSLT in hypersomnia conditions is poor. 7 The fact that reported mean sleep latencies in the cohort of Szakacs et al (4.2-4.7 minutes) were somewhat higher than reported in other cohorts including ours (2.6-2.9 minutes), leaves some uncertainty about patient inclusion. 2,8 Even if there remain this and other minor methodological concerns, this study is important and deserves attention by clinicians, politicians, and scientists, and here is why:…”

A Patient with Intractable Attacks of Cataplexy

“…1 The MSLT as a diagnostic tool in hypersomnias of central origin has been challenged by the presence of SOREMPs in many other conditions (e.g., obstructive sleep apnea); and the poor test-retest reliability of the MSLT. 9 Cataplexy, however, is considered pathognomic of narcolepsy and should be carefully investigated in each patient. The concomitant diagnosis of OSA, narcolepsy, and pseudo-cataplexy in our patient cannot be definitively excluded.…”