What Is a Tonic-Clonic Seizure?


Quick Answer

A tonic-clonic seizure, known also as a grand mal seizure, is a full-body seizure characterized by loss of consciousness, stiffness and convulsions, according to WebMD. They often occur in individuals with epilepsy but may also occur as a one-time event in others.

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Full Answer

The tonic phase happens first and causes the body to stiffen with contracted muscles and an arched back. The victim loses consciousness quickly during this phase, which lasts about 15 to 30 seconds, notes WebMD. Some people turn blue during the tonic phase because they stop breathing.

The convulsions begin during the clonic phase. Tonic-clonic seizures typically last only one or two minutes. Some people bite their tongues, clench their teeth, have trouble breathing or lose control of urine and bowel movements, states MedlinePlus. The person often remains unconscious even after the seizure stops, gradually waking up over the 30-minute period following the seizure.

Drowsiness often occurs after the seizure sometimes up to an hour or more, says MedlinePlus. A tonic-clonic seizure can also cause amnesia or confusion. Some people experience headaches or weakness after the event. An exam by a doctor with an EEG and possible blood tests helps determine the cause of the tonic-clonic seizure. Treatment options to prevent future tonic-clonic seizures include a variety of medications.

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