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Clinical Review Lesson of the week

Narcolepsy mistaken for epilepsy

BMJ 2001; 322 doi: (Published 27 January 2001) Cite this as: BMJ 2001;322:216
  1. Adam Zeman (, consultant neurologista,
  2. Neil Douglas, professorb,
  3. Rebecca Aylward, locum consultant neurologistc
  1. a Department of Clinical Neurosciences, Western General Hospital, Edinburgh EH2 2XU
  2. b Sleep Laboratory, Royal Infirmary of Edinburgh, Edinburgh EH3 9YW
  3. c Epilepsy Clinic, Falkirk Royal Infirmary, Falkirk FK1 5QE
  1. Correspondence to: A Zeman
  • Accepted 3 October 2000

Narcolepsy is common: its cardinal symptoms can give rise to confusion with epilepsy

Narcolepsy is a distinctive but underdiagnosed disorder of sleep and waking. Its cardinal manifestations are: (a) excessive daytime sleepiness, with a tendency to nap repeatedly through the day; (b) cataplexy, a loss of muscle tone triggered by emotion, causing immobility for seconds to minutes; (c) hypnagogic hallucinations, vivid visual or auditory phenomena, experienced at the onset of sleep; and (d) sleep paralysis, an inability to move on first awakening.1

When a patient describes all these symptoms the diagnosis should be straightforward. Diagnostic difficulty arises when patients present with isolated symptoms, or if their story suggests some more familiar diagnosis. We report on three patients recently encountered in whom narcolepsy was initially mistaken for epilepsy. Indeed, Gelineau, the French physician who coined the term “narcolepsy” in 1880, was at pains to distinguish his novel disorder of sleep (narco from the Greek for “sleep” and “lepsy” for taken hold by) from epilepsy, with which he thought it might be confused. 2 3

Case reports

Case 1—A 26 year old woman was found in the bath “unable to move, speak, or get out.” Her husband reported flickering of the eyelids and muscle twitching. Her speech was slurred as she recovered, over minutes. The referral letter noted a history of short periods of apparent daytime sleep, sometimes at inappropriate moments—for example, during meals—and a tendency to “go weak and limp … if she is having a carry-on or laughing heartily.” The diagnosis at referral was of complex partial seizures; sodium valproate had been prescribed. It emerged that she had clear recall of her period of immobility in the bath: it resembled her episodes of weakness on laughing. On direct questioning she described sleep paralysis and hypnagogic hallucinations. She tended to sleep …

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