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Narcolepsy Type 1 Without Cataplexy — SCE Neurology MCQ

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HardSleep DisordersNarcolepsy Type 1 Without CataplexySCE Neurology

A 50-year-old man with excessive daytime sleepiness but no cataplexy has MSLT showing mean sleep latency 5 min with 3 SOREMPs. CSF hypocretin is 45 pg/mL (<110 pg/mL). What is the diagnosis?

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Correct answer: B — Narcolepsy type 1

Despite no cataplexy, CSF hypocretin <110 pg/mL is diagnostic of narcolepsy type 1. ICSD-3 allows NT1 diagnosis with cataplexy OR low hypocretin. Some patients develop cataplexy later. A: NT2 has normal hypocretin. C: IH lacks SOREMPs. D: Excluded by normal PSG sleep. E: KLS has episodic hypersomnia.

Reference: AASM ICSD-3 (2014)