What Is a Grand Mal Seizure?

Understanding grand mal seizures

woman fainted on ground
Science Photo Library/Getty Images


Generalized 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.

More information About Grand Mal Seizures:

About 10 percent of all people with epilepsy experience grand mal or generalized, tonic-clonic seizures. Furthermore, when the metabolites (blood salts) in your blood are out of whack, these seizures can also occur.

Such metabolic derangement occurs in a variety of clinical settings.

Although grand mal seizures usually begin without warning, some people describe the premonition or aura indicating that these seizures are about to occur in the hours before the seizures actually do happen.  

During the ictal or active phase of a grand mal seizure, the expiratory muscles and larynx can contract resulting in a distinctive moan or cry ("ictal cry").

Additionally, secretions may pool in the mouth and lungs leading to cyanosis or bluish discoloration of the skin caused by decreased circulation. Contraction of the jaw can also cause a person having a grand mal seizure to bite her tongue and bleed. Finally, activation of the sympathetic nervous system experienced during a grand mal seizure can result in increased blood pressure, increased heart rate, and pupillary dilation.

During the relaxation or postictal phase of a grand mal seizures, a person may also experience difficulties breathing on account of excess salivation. Additionally, a person may also lose bowel and bladder control during this period. People experiencing grand mal seizures can exhibit confusion that lasts for several hours. Even after this confusion abates, a person who has just experienced a grand mal seizure may experience headaches, fatigue and muscle aches. Essentially, the repercussions of a grand mal seizure aren't merely acute and deficits and discomfort may persist for hours.

An electroencephalogram or EEG done during a grand mal seizure shows characteristic findings depending on the phase of the seizure.

Of note, there are variations in how people experience grand mal seizures. For example, some people experience pure tonic or pure clonic seizures. Moreover, some people, like those with specific epileptic syndromes, experience brief tonic seizures that last only a few seconds.


John Hopkins Medicine. “Tonic-Clonic (Grand Mal) Seizures.” Accessed September 2013.

Epilepsy Foundation of America. “Tonic-Clonic Seizures." Accessed September 2013.

Continue Reading