Cataplexy

What is Cataplexy?

Cataplexy is a sudden and transient loss of muscle tone, caused by a strong emotion or a fit of laughter. The affected subject suddenly collapses to the ground without losing consciousness.

Cataplexy is a rare but common neurological disorder in people with narcolepsy (occurs in about 70% of cases). It can manifest itself with a series of physical changes, partial or generalized: from difficulty in articulating words (dysarthria), to weakness of the knees, to complete atony. During a cataplectic attack, the subject loses voluntary control of the muscles and can fall on the ground, but always remains conscious and alert. Episodes may last a few minutes and are often triggered by an emotional stimulus such as laughter, fear, anger, surprise or excitement. Treatment involves the use of anticataplectic drugs (sodium oxybate or antidepressants).

Causes

The exact cause of cataplexy is unknown, but the condition is strongly associated with emotional stimuli. Emotions that can trigger a cataplectic event include: laughter, fear, anger, frustration, irritation, nervousness, embarrassment, and sadness. As soon as the stimulation is reduced. , the person regains normal muscle control Emotions can be even modest, while at other times an attack occurs spontaneously, in the absence of an apparent cause.
The loss of muscle tone, which occurs in cataplexy, resembles the "interruption of muscle activity that occurs naturally during REM sleep: the sudden weakness of the muscles of the body could be caused by a" massive inhibition of motor neurons in the spinal cord. , caused by a dysfunction of the sleep-wake cycle. Using an animal model, scientists learned that this same group of neurons are inactive during cataplectic attacks.