Grand mal seizure

Synonyms: Tonic-clonic seizure

Medical Specialties: Emergency medicine, Internal medicine, Neurology

Clinical Definition

A grand mal seizure is a generalized seizure, involving both sides of the brain and loss of consciousness. It is characterized by two main phases, including the tonic phase and the clonic phase. The tonic phase consists of the sudden onset of muscle rigidity. The seizure then progresses into the clonic phase, which involves muscle contractions. 

In Our Own Words

Grand mal seizures arise from a disruption in the normal electrical activity in the brain. Often frightening to watch, they have a widespread impact on the people who suffer from them.


A grand mal seizure typically starts with losing consciousness and falling to the ground. Muscles will tighten throughout the body, which may cause the eyes to roll back, breathing to become impaired and lips to turn blue. The second phase of the seizure involves muscle convulsions, or jerky movements. This phase generally does not last longer than a few minutes, after which normal breathing returns. Time for recovery varies from person to person, but a period of confusion after a seizure is common.

Relevant Conditions
Side Effects
  • Loss of consciousness
  • Muscle tightening
  • Convulsions
Share this article
  • John Hopkins Medicine. “Tonic-Clonic (Grand Mal) Seizures.” Accessed September 2013.
  • Epilepsy Foundation of America. “Tonic-Clonic Seizures.” Accessed September 2013.
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