Sleep spindle density in narcolepsy

• Published in: Sleep medicine Vol. 34; pp. 40 - 49
• Main Authors: Christensen, Julie Anja Engelhard, Nikolic, Miki, Hvidtfelt, Mathias, Kornum, Birgitte Rahbek, Jennum, Poul
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2017
• Subjects: Adult; Automatic detection; Brain - physiopathology; Electroencephalography; Female; Humans; Male; Narcolepsy; Narcolepsy - chemically induced; Narcolepsy - physiopathology; Neurology; Nocturnal distribution of spindles; Pattern Recognition, Automated; Polysomnography; Sleep Medicine; Sleep spindle density; Sleep Stages - physiology; SS; electroencephalography; AASM; PSG; EEG; multiple sleep latency test; NT1; MSLT; Cerebrospinal fluid; NT2; rapid eye movement; Automatic detection; sleep spindles; Nocturnal distribution of spindles; electromyography; CSF; Narcolepsy type 1; American Academy of Sleep Medicine; Narcolepsy; Sleep spindle density; Narcolepsy type 2; polysomnography; REM; EMG
• ISSN: 1389-9457; 1878-5506
• DOI: 10.1016/j.sleep.2017.02.022

Abstract Background Patients with narcolepsy type 1 (NT1) show alterations in sleep stage transitions, rapid-eye-movement (REM) and non-REM sleep due to the loss of hypocretinergic signaling. However, the sleep microstructure has not yet been evaluated in these patients. We aimed to evaluate whether the sleep spindle (SS) density is altered in patients with NT1 compared to controls and patients with narcolepsy type 2 (NT2). Methods All-night polysomnographic recordings from 28 NT1 patients, 19 NT2 patients, 20 controls (C) with narcolepsy-like symptoms, but with normal cerebrospinal fluid hypocretin levels and multiple sleep latency tests, and 18 healthy controls (HC) were included. Unspecified, slow, and fast SS were automatically detected, and SS densities were defined as number per minute and were computed across sleep stages and sleep cycles. The between-cycle trends of SS densities in N2 and NREM sleep were evaluated within and between groups. Results Between-group comparisons in sleep stages revealed no significant differences in any type of SS. Within-group analyses of the SS trends revealed significant decreasing trends for NT1, HC, and C between first and last sleep cycle. Between-group analyses of SS trends between first and last sleep cycle revealed that NT2 differ from NT1 patients in the unspecified SS density in NREM sleep, and from HC in the slow SS density in N2 sleep. Conclusions SS activity is preserved in NT1, suggesting that the ascending neurons to thalamic activation of SS are not significantly affected by the hypocretinergic system. NT2 patients show an abnormal pattern of SS distribution.