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Information ⬇

A disorder of excessive daytime sleepiness and intrusion of REM-related sleep phenomena into wakefulness (cataplexy, hypnagogic hallucinations, and sleep paralysis). Cataplexy, the abrupt loss of muscle tone in arms, legs, or face, is precipitated by emotional stimuli such as laughter or sadness. Symptoms of narcolepsy typically begin in the second decade. The prevalence is 1 in 2000. Narcolepsy has a genetic basis; almost all narcoleptics with cataplexy are positive for HLA DQB1*0602. Hypothalamic neurons containing the neuropeptide hypocretin (orexin) regulate the sleep/wake cycle and loss of these cells, possibly due to autoimmunity, has been implicated in narcolepsy. Diagnosis is made with sleep studies confirming a short daytime sleep latency and a rapid transition to REM sleep.

Treatment: Narcolepsy

  • Somnolence is treated with modafinil (200-400 mg/d given as a single dose each morning).
  • Older stimulants such as methylphenidate (10-20 mg bid) or dextroamphetamine (10 mg bid) are alternatives, particularly in refractory pts.
  • Cataplexy, hypnagogic hallucinations, and sleep paralysis respond to the tricyclic antidepressants protriptyline (10-40 mg/d) and clomipramine (25-50 mg/d) and to fluoxetine (10-20 mg each morning) and venlafaxine (37.5-150 mg each morning). Alternatively, sodium oxybate given at bedtime, and 3-4 h later, is effective in reducing daytime cataplectic episodes.
  • Adequate nocturnal sleep time and the use of short naps are other useful preventative measures.

Outline ⬆

Section 3. Common Patient Presentations