Abstract
A multiple sleep latency test (MSLT) with occurrence of sleep onset REM periods (SOREMP) is considered one of the central diagnostic criteria for narcolepsy according to the International Classification of Sleep Disorders, but its sensitivity and specificity have been questioned. This study aims to describe MSLT and polysomnography (PSG) findings, including frequency and distribution of SOREMP during the day, in a large cohort of patients with central disorders of hypersomnolence (CDH).We retrospectively analyzed electrophysiological data from MSLT and PSG in 370 consecutive patients with narcolepsy type 1 (NT1, n = 97), type 2 (NT2, n = 31), idiopathic hypersomnia (IH, n = 48), nonorganic hypersomnia (NOH, n = 116) and insufficient sleep syndrome (ISS, n = 78).NT1 and NT2 patients had a significantly shorter mean Sleep Latency (mSL) and REM-Latency (REML) in MSLT and PSG. SOREMP occurred more frequently in narcoleptic vs. non-narcoleptic patients in MSLT and PSG. Occurrence of 3 or more SOREMP in MSLT and a SOREMP in PSG had a very high specificity and positive predictive value (98%/96% and 100% respectively), however relatively low sensitivity (65% and 45% respectively).NT1 more than NT2 patients have shorter mSL and more frequent SOREMP in MSLT and shorter SL as well as REML during nocturnal PSG. Increasing numbers of SOREMP in MSLT and especially SOREMP during PSG increase specificity on the expense of sensitivity in diagnosing narcolepsy. Therefore, frequency of SOREMP in MSLT naps and PSG can help to discriminate but not clearly separate narcoleptic from non-narcoleptic patients.
Highlights
Excessive daytime sleepiness (EDS) was reported by up to 28% of the general adult US population in a study by Ohayon et al, but the prevalence depends on the exact definition [1]
As summarized in table 1, 97 (26%) patients were diagnosed with narcolepsy type 1 (NT1), 31 (8%) with narcolepsy type 2 (NT2), 48 (13%) with IH, 116 (31%) with non-organic hypersomnia (NOH), and 78 (21%) with insufficient sleep syndrome (ISS)
292 (79%) patients underwent both PSG and multiple sleep latency test (MSLT), while 56 (15%) had only PSG. 77% patients completed 5 MSLT trials, 21% 4 trials and 2% less than 4 trials
Summary
Excessive daytime sleepiness (EDS) was reported by up to 28% of the general adult US population in a study by Ohayon et al, but the prevalence depends on the exact definition [1]. Seneviratne et al found that up to 14% of patients with sleep-disordered breathing (SDB) had 2 or more SOREMP in the MSLT with a mean sleep latency (mSL) of 4.5 min in a clinically sleepy patient group [7]. Marti et al found that 15% of patients with behaviorally induced insufficient sleep syndrome (ISS) had an MSLT suggestive of narcolepsy (mSL ≤ 8 min and at least two SOREMP) [8]. In line with these findings Drakatos et al found 1 SOREMP in the MSLT of IH (1%), ISS (7.14%) and periodic limb movement disorder (4.7%) patients [9]. Occurrence of SOREMP during nocturnal PSG has been found highly specific for NT1 [10]
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