Hypocretin (orexin) deficiency predicts severe objective excessive daytime sleepiness in narcolepsy with cataplexy.
Cerebrospinal fluid (CSF) hypocretin-1 deficiency is associated with definite ("clear cut") cataplexy in patients with narcolepsy. The relationship between CSF hypocretin-1 levels and other narcoleptic symptoms (including excessive daytime sleepiness, EDS) is not properly understood. In a consecutive series of 18 subjects with narcolepsy and definite cataplexy, patients with undetectable CSF hypocretin-1 (n = 12) were found to have significantly lower mean sleep latencies (p = 0.045) and a higher frequency of sleep onset REM periods (SOREMPs, p = 0.025) on multiple sleep latency test than patients (n = 6) with detectable levels. Conversely, Epworth sleepiness scale scores, the frequency of hallucinations/sleep paralysis, and the frequency and severity of cataplexy were similar in both groups. These results suggest that hypocretin deficiency identifies a homogenous group of patients with narcolepsy characterised by the presence of definite cataplexy, severe EDS, and frequent SOREMPs.
Department of Neurology, University Hospital Zürich, Frauenklinikstrasse 26, 8091 Zürich, Switzerland.
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Baumann
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Khatami
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Werth
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Bassetti
D000293:Adolescent; D000328:Adult; D002385:Cataplexy / Q000134:cerebrospinal fluid* / Q000175:diagnosis*; D006970:Disorders of Excessive Somnolence / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency*; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D009479:Neuropeptides / Q000172:deficiency*; D000068797:Orexins; D017286:Polysomnography; D011237:Predictive Value of Tests; D011379:Prognosis; D012895:Sleep, REM / Q000502:physiology
C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins