cataplexy

Etiology

• cataplexy is pathognomonic for narcolepsy
• related to
  • narcolepsy
  • excessive daytime sleepiness
  • hypnagogic hallucination
  • sleep paralysis

Epidemiology

• present in 70% of patients with narcolepsy

Clinical manifestations

• generally provoked by laughter or anticipatory emotion
• sudden loss of muscle strength & muscle tone
  • due to intrusion of rapid-eye-movement (REM) into wakefulness
  • no tonic-clonic activity
• may be unable to move or speak
• awake, no loss of consciousness
• no incontinence
• muscle atonia
• deep tendon reflexes (DTR) are lost during the episode, but return promptly afterwards
• some patients become withdrawn or develop a flat affect in attempt to avoid emotional triggers
• no post-ichtal state
• victims able to recall entire event

Diagnostic procedures

• polysomnography followed by
  • multiple sleep latency test

Differential diagnosis

• syncope associated with loss of consciousness
• seizure associated with loss of consciousness

Management

• gamma-hydroxybutyrate [sodium oxybate] (Xyrem) is treatment of choice
• tricyclic antidepressants
  • clomipramine (Anafranil) 25-75 mg QD
  • protriptyline (Vivactil) 5-20 mg QD
  • imipramine (Tofranil) 50-75 mg QHS
• fluoxetine (Prozac) 20-80 mg QD

More general terms

• psychiatric disease; behavioral disorder
• chronic mental disorder

Additional terms

• catatonia
• narcolepsy