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Idiopathic Hypersomnia — SCE Neurology MCQ

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HardSleep DisordersIdiopathic HypersomniaSCE Neurology

A 31-year-old has recurrent emotion-triggered cataplexy. Overnight polysomnography confirms adequate sleep, excludes sleep apnoea and shows a sleep-onset REM period. Next-day multiple sleep latency testing shows a mean latency of 6.5 minutes but only one sleep-onset REM period. Confounding drugs and other causes have been excluded. Which interpretation matches the ICSD-3-TR text revision?

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Correct answer: B — Cataplexy plus the overnight sleep-onset REM period can fulfil criterion B for narcolepsy type 1

The ICSD-3-TR text revision allows cataplexy plus a sleep-onset REM period on nocturnal polysomnography to fulfil criterion B for narcolepsy type 1. The earlier wording required a mean MSLT sleep latency of 8 minutes or less with at least two sleep-onset REM periods. Therefore, only one MSLT sleep-onset REM period does not exclude narcolepsy type 1 when typical cataplexy and the qualifying overnight finding are present. Cataplexy is incompatible with narcolepsy type 2, and a low MSLT REM count alone does not establish idiopathic hypersomnia.

Reference: International Classification of Sleep Disorders, third edition text revision, supplemental diagnostic criteria: https://aasm.org/wp-content/uploads/2023/05/ICSD-3-Text-Revision-Supplemental-Material.pdf