Definition of Generalized Seizures

About 10 percent of people experience a seizure sometime during their lifetime and roughly three percent of people will be diagnosed with epilepsy by age 80, according to the Centers for Disease Control and Prevention. Numerous types of seizures exist. Generalized seizures occur when a cluster of nerve cells in the brain abnormally fire in the left and right hemispheres. There are several generalized seizure classifications.

Tonic-Clonic Seizures

• The most common type of generalized seizures are tonic-clonic seizures. A patient experiences such a seizure, sometimes called grand mal seizures, in phases starting with unclear symptoms a few hours or days before the attack.

Tonic Seizures

• In tonic a seizure the person experiences non-vibrating muscle contractions in the arms and legs. During a tonic seizure, a person's consciousness is impaired.

Atonic Seizures

• During an atonic seizure the person has an one to two second episode. A person briefly goes unconscious and his posture limps.

Clonic Seizures

• During a clonic seizure a person loses consciousness quickly. The patient's body experiences a tonic spasm, jerking movements and loss of muscle tone. The patient's muscles are stiff for about 30 seconds, however the muscles continue to contract and relax during this phase.

Absence Seizures

• Generally absence seizures affect children from age four to adolescence. The patient experiences a consciousness loss, lasting one to 10 seconds. A person experiencing this episode may have a blank stare, blink rapidly, roll eyes and move lips. Afterward, the person will continue their previous activities, and may possibly be unaware of the seizure.

Myoclonic Seizures

• In a myoclonic seizure muscles contract quickly. The person's facial and pelvic muscles jerk during a myoclonic seizure.