May also be called: Muscle Twitch; Muscle Jerk
Myoclonus (my-o-klo-nus) is a sudden, involuntary twitching, jerking, or contraction of a muscle or group of muscles.
Muscles are controlled by electrical impulses in the central nervous system. Sometimes, even healthy people experience an abnormal electrical impulse that can cause a muscle or group of muscles to contract suddenly. Hiccups are an example of this type of contraction, and so are the muscle twitches that many people experience as they try to fall asleep.
Brief myoclonus in a single muscle can be a normal, harmless occurrence, but in some cases involuntary muscle twitching can be a symptom of a serious condition like epilepsy, stroke, brain tumors, infection, multiple sclerosis, genetic disorders, metabolic disorders, or an injury to the brain or spinal cord.
In healthy people, brief, occasional muscle twitches are generally nothing to worry about. If myoclonus happens a lot, lasts long, or is associated with other symptoms, it should be evaluated by a doctor to determine if an underlying condition is the cause. Treatment for myoclonus usually involves treating the muscle contractions and their underlying cause with medications.
All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.
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