Convulsion

Convulsion, involuntary contraction of the muscles of the body. Such contractions may be tonic or clonic, according to whether they are continuous or spasmodic, and of either cerebral or spinal origin. Convulsions may be caused by lack of oxygen (e.g., convulsions during some bouts of fainting), toxic conditions (e.g., convulsions due to the poison strychnine), psychological factors (e.g., hysterical convulsions), or epilepsy. The term “convulsion” now usually refers to discontinuous muscular contractions, either brief contractions repeated at short intervals or longer ones interrupted by intervals of muscular relaxation.

See also: Epilepsy.