Clonic seizures are similar to generalized tonic-clonic seizures but consist only of rhythmic or semi-rhythmic contractions of a group of muscles. (That is, there is no tonic phase.) These jerks can involve any muscle group. The arms, neck, and facial muscles are most commonly involved.
Clonic seizures are much more common in children than adults.
Reviewed and revised January 2004 by Gregory L. Holmes, MD, Dartmouth Medical School
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