Narcolepsy — clinical spectrum, aetiopathophysiology, diagnosis and treatment

• Published in: Nature reviews. Neurology 2019-09, Vol.15 (9), p.519-539
• Main Authors: Bassetti, Claudio L. A., Adamantidis, Antoine, Burdakov, Denis, Han, Fang, Gay, Steffen, Kallweit, Ulf, Khatami, Ramin, Koning, Frits, Kornum, Brigitte R., Lammers, Gert Jan, Liblau, Roland S., Luppi, Pierre H., Mayer, Geert, Pollmächer, Thomas, Sakurai, Takeshi, Sallusto, Federica, Scammell, Thomas E., Tafti, Mehdi, Dauvilliers, Yves
• Format: Article
• Language: English
• Subjects: 631/250/21/324/1508; 631/378/1385/2642; 692/1807/1693; 692/699/249; 692/699/375/1816; Brain - physiopathology; Care and treatment; Development and progression; Diagnosis; Hallucinations; Humans; Hypothalamus - physiopathology; Life Sciences; Medicine; Medicine & Public Health; Metabolism; Narcolepsy; Narcolepsy - diagnosis; Narcolepsy - etiology; Narcolepsy - physiopathology; Narcolepsy - therapy; Neurology; Neurons and Cognition; Orexins - physiology; Review Article; Sleep disorders
• ISSN: 1759-4758; 1759-4766
• DOI: 10.1038/s41582-019-0226-9

Narcolepsy is a rare brain disorder that reflects a selective loss or dysfunction of orexin (also known as hypocretin) neurons of the lateral hypothalamus. Narcolepsy type 1 (NT1) is characterized by excessive daytime sleepiness and cataplexy, accompanied by sleep–wake symptoms, such as hallucinations, sleep paralysis and disturbed sleep. Diagnosis is based on these clinical features and supported by biomarkers: evidence of rapid eye movement sleep periods soon after sleep onset; cerebrospinal fluid orexin deficiency; and positivity for HLA-DQB1*06:02. Symptomatic treatment with stimulant and anticataplectic drugs is usually efficacious. This Review focuses on our current understanding of how genetic, environmental and immune-related factors contribute to a prominent (but not isolated) orexin signalling deficiency in patients with NT1. Data supporting the view of NT1 as a hypothalamic disorder affecting not only sleep–wake but also motor, psychiatric, emotional, cognitive, metabolic and autonomic functions are presented, along with uncertainties concerning the ‘narcoleptic borderland’, including narcolepsy type 2 (NT2). The limitations of current diagnostic criteria for narcolepsy are discussed, and a possible new classification system incorporating the borderland conditions is presented. Finally, advances and obstacles in the symptomatic and causal treatment of narcolepsy are reviewed. In the past 20 years, understanding of the clinical manifestations, aetiopathophysiology, diagnosis and treatment of narcolepsy has greatly advanced. In this Review, Bassetti et al. present these advances, discuss unmet needs and offer future perspectives for the field of narcolepsy. Key points Narcolepsy is a rare and often disabling hypothalamic disorder that presents with sleep–wake dysregulation (excessive daytime sleepiness (EDS), cataplexy, hallucinations, sleep paralysis and disturbed sleep) and motor, cognitive, psychiatric, metabolic and autonomic disturbances. Narcolepsy arises from the interaction of genetic and environmental factors, which lead to an immune-mediated selective loss or dysfunction of orexin neurons in the lateral hypothalamus. Patients with narcolepsy type 1 have cataplexy and little or no orexin in cerebrospinal fluid; narcolepsy type 2 is a diagnosis of exclusion requiring ancillary tests ruling out other causes of EDS. Several drugs (including modafinil, sodium oxybate, pitolisant, solriamfetol and methylphenidate) improve narcoleptic symptoms