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Narcolepsy Type 2 – Diagnosis — SCE Neurology MCQ

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HardSleep DisordersNarcolepsy Type 2 – DiagnosisSCE Neurology

A 29-year-old has disabling sleepiness, sleep paralysis and hypnagogic hallucinations but no cataplexy. Actigraphy confirms adequate sleep before polysomnography, which excludes sleep apnoea. MSLT shows mean latency 5 minutes and three sleep-onset REM periods. CSF hypocretin is not measured. What is the best classification?

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Correct answer: D — Narcolepsy type 2, provided competing causes remain excluded

Objective pathological sleepiness with at least two sleep-onset REM periods supports narcolepsy. Type 1 requires cataplexy or hypocretin deficiency; in their absence, and after excluding sleep deprivation, circadian disorder, medication effects and sleep apnoea, the classification is type 2. Idiopathic hypersomnia lacks the characteristic REM pattern, and delayed-phase or recurrent hypersomnia has a different longitudinal phenotype.

Reference: European guideline and expert statements on narcolepsy management (Published September 2021): https://pubmed.ncbi.nlm.nih.gov/34173695/