Sleep

Narcolepsy

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Narcolepsy

  • Epidemiology
  1. Prevalence: 40 per 100,000 (0.02 to 0.18% of adults)
  2. Men and women affected equally
  3. Onset in adolescence to early 20s (rarely has onset after age 50 years)
  • Pathophysiology
  1. Excessive Sleepiness
  2. Abnormal REM Sleep
  • Causes
  1. Idiopathic
    1. Hereditary related to DR-2
  2. Secondary causes
    1. Head Trauma
    2. Encephalopathy
    3. Brain Tumor
    4. Cerebrovascular insufficiency
  • Symptoms
  • Classic Tetrad
  1. Recurrent irresistible Daytime Sleepiness
    1. Occurs unexpectedly and at inappropriate times
  2. Cataplexy (25-30% of patients with Narcolepsy)
    1. Sudden decrease or loss of voluntary muscle tone following emotional trigger (e.g. laughing, surprise)
    2. Episodes last seconds to minutes
      1. Localized hypotonia (e.g. jaw drop, head nod, knee sag)
      2. Generalized hypotonia (full collapse onto floor)
  3. Hallucinations
    1. Hypnagogic Hallucinations (on falling asleep)
    2. Hypnopompic Hallucinations (on awakening)
  4. Sleep Paralysis
    1. Transient, generalized inability to move or speak during sleep-wake transition
  • Differential Diagnosis
  1. See Hypersomnolence
  2. Sleep Apnea
  3. Other Primary Hypersomnia (uncommon)
    1. Idiopathic Hypersomnia
    2. Menstrual Hypersomnia
    3. Kleine-Levin Syndrome (rare syndrome of male teens)
  • Evaluation
  1. Sleep log or actigraphy for 2 weeks
  2. Multiple Sleep Latency Test (daytime nap test)
    1. At least 2 naps with early onset REM Sleep (Rapid transition to REM)
    2. Shortened REM latency (<8 minutes)
  • Management
  • Standard Medications
  1. See Hypersomnia
  2. First-Line Stimulants
    1. Modafinil (Provigil)
      1. Best safety profile and lowest abuse potential of all stimulant agents
    2. Armodafinil (Nuvigil, generic)
    3. Solriamfetol (Sunosi, expensive)
  3. Other stimulants (risk of dependence)
    1. Methylphenidate (Ritalin)
    2. Dextroamphetamine (Dexedrine)
  4. Symptomatic management of Cataplexy, Sleep Paralysis or hypnagogic Hallucinations
    1. SNRI (e.g. Effexor) and SSRI agents suppress REM Sleep
  5. Other agents
    1. Gamma hydroxybutyric acid or Sodium oxybate (Xyrem)
      1. Given twice nightly