Cataplexy

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Cataplexy is a sudden, brief episode of muscle weakness that happens while you’re fully awake and aware. The strength loss is often triggered by strong emotions like laughing, crying, surprise, or quick physical effort. Attacks usually last several seconds to a few minutes and may involve the face, neck, or knees. People often fall slowly, so they can usually protect themselves and avoid injury. Speech can be slurred and vision may blur, but hearing and thinking stay normal.

Most cataplexy occurs with narcolepsy, a sleep disorder. It happens because brain cells that make hypocretin (also called orexin), a chemical that helps keep us awake, are damaged or missing. In rare cases, cataplexy occurs without narcolepsy.

Causes and what happens in the brain:
- Hypocretin deficiency lets REM sleep paralysis spill over into wakefulness, causing muscle weakness.
- Lesions in the hypothalamus or other brain problems (like tumors or brain injuries) can cause secondary cataplexy.
- Other conditions such as multiple sclerosis, head injury, infections, or certain brain changes can be involved.

Diagnosis:
- Doctors diagnose narcolepsy and cataplexy mainly from symptoms and medical history.
- A sleep study called a multiple sleep latency test can help measure daytime sleepiness.

Treatment:
- There is no cure, but symptoms can be managed.
- Sodium oxybate (gamma-hydroxybutyrate) can reduce cataplexy and improve night sleep.
- Antidepressants such as venlafaxine or clomipramine can help reduce REM-related symptoms.
- Histamine H3 blockers like Pitolisant may help increase wakefulness.
- Safety measures and protective devices can prevent injuries during attacks.
- Treatment is often lifelong and tailored to the person.

Ongoing research is exploring ways to replace or repair hypocretin-producing neurons.