Novel method for evaluation of eye movements in patients with narcolepsy.
BACKGROUND
Narcolepsy causes abnormalities in the control of wake-sleep, non-rapid-eye-movement (non-REM) sleep and REM sleep, which includes specific eye movements (EMs). In this study, we aim to evaluate EM characteristics in narcolepsy as compared to controls using an automated detector.


METHODS
We developed a data-driven method to detect EMs during sleep based on two EOG signals recorded as part of a polysomnography (PSG). The method was optimized using the manually scored hypnograms from 36 control subjects. The detector was applied on a clinical sample with subjects suspected for central hypersomnias. Based on PSG, multiple sleep latency test and cerebrospinal fluid hypocretin-1 measures, they were divided into clinical controls (N = 20), narcolepsy type 2 (NT2, N = 19), and narcolepsy type 1 (NT1, N = 28). We investigated the distribution of EMs across sleep stages and cycles.


RESULTS
NT1 patients had significantly less EMs during wake, N1, and N2 sleep and more EMs during REM sleep compared to clinical controls, and significantly less EMs during wake and N1 sleep compared to NT2 patients. Furthermore, NT1 patients showed less EMs during NREM sleep in the first sleep cycle and more EMs during NREM sleep in the second sleep cycle compared to clinical controls and NT2 patients.


CONCLUSIONS
NT1 patients show an altered distribution of EMs across sleep stages and cycles compared to NT2 patients and clinical controls, suggesting that EMs are directly or indirectly controlled by the hypocretinergic system. A data-driven EM detector may contribute to the evaluation of narcolepsy and other disorders involving the control of EMs.
['Christensen|Julie A E|JAE|', 'Kempfner|Lykke|L|', 'Leonthin|Helle L|HL|', 'Hvidtfelt|Mathias|M|', 'Nikolic|Miki|M|', 'Kornum|Birgitte Rahbek|BR|', 'Jennum|Poul|P|']
D000293:Adolescent D000328:Adult D003718:Denmark D006970:Disorders of Excessive Somnolence D004585:Electrooculography D005133:Eye Movements D005260:Female D006801:Humans D047908:Intracellular Signaling Peptides and Proteins D008297:Male D008875:Middle Aged D009290:Narcolepsy D000068797:Orexins D017286:Polysomnography D012890:Sleep D012894:Sleep Stages D012893:Sleep Wake Disorders D012895:Sleep, REM D055815:Young Adult
Narcolepsy Polysomnography Automatic classification Electrooculography Eye movements during sleep Hypocretin versus non-hypocretin deficiency