A spasm is an involuntary contraction of a muscle or group of muscles that cannot be controlled by the patient. Some muscle spasms can cause pain in the affected area. Others can cause a twitch or tic. Severe spasms can cause convulsions.
Muscle spasms are usually the result of overstressing a muscle and can be treated with muscle relaxants, which make it more difficult for muscles to contract without voluntary control. However, some spasms are the result of serious underlying conditions.