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Narcolepsy Type 1 — RACP Adult Medicine MCQ

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ModerateNeurologyNarcolepsy Type 1RACP Adult Medicine

A 42-year-old woman presents with excessive daytime sleepiness despite adequate sleep (8–9 hours), cataplexy (sudden muscle weakness triggered by laughter), sleep paralysis, and hypnagogic hallucinations. PSG shows shortened REM latency. CSF hypocretin (orexin) level is undetectable. What is the most likely diagnosis?

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Correct answer: B — Narcolepsy type 1

Excessive daytime somnolence with cataplexy, sleep paralysis, hypnagogic hallucinations, shortened REM latency, and undetectable CSF hypocretin defines narcolepsy type 1. It is caused by autoimmune destruction of hypocretin-producing neurons. Treatment includes scheduled naps and pharmacotherapy (modafinil/armodafinil for sleepiness, sodium oxybate for cataplexy).

Reference: AASM – 2024 – Narcolepsy Guidelines