Cataplexy Associated with Narcolepsy
Cataplexy is a sudden, involuntary loss of muscle tone that occurs in people with narcolepsy. An episode can range from a fleeting weakness in the face or knees to a complete collapse of the body, and it is nearly always set off by a strong emotion, laughter, surprise, anger, or excitement. Consciousness is fully preserved throughout, which is what distinguishes cataplexy from a seizure or fainting.
Key points
- Full awareness is kept throughout an episode, the key feature that sets cataplexy apart from a seizure or fainting spell.
- A strong emotion such as laughter or a sudden fright almost always sets off an episode, which usually passes within minutes.
- Clomipramine, a tricyclic antidepressant, dampens the REM-related muscle atonia behind episodes, usually needing several weeks before its full effect appears.
What triggers an episode and how long it lasts
Most episodes last only a few seconds to a couple of minutes and resolve on their own. The emotional trigger is the defining feature: a burst of laughter at a joke, a sudden fright, or even anticipation can be enough. Some people notice a mild warning such as facial twitching or drooping eyelids before muscle control gives way.
Because narcolepsy is often under-recognised, many people live with cataplexy for years before receiving a diagnosis.
Medicines used for cataplexy
The main pharmacological approach is to reduce the frequency and severity of episodes. Clomipramine, a tricyclic agent from the antidepressants category, suppresses REM-related muscle atonia and has been used for cataplexy for several decades. It is typically taken at a low daily dose and may take a few weeks to show full benefit.
If episodes are severe, frequent, or causing injury, a sleep neurologist should be involved in managing the condition alongside any medicines used.