Epilepsy - Introduction

While the term "partial" implies the seizures affect only small or specific brain locations, in reality, they almost always involve diffuse and even widespread areas. In the future, the term "focal seizures" will most likely replace the term "partial seizures," and its subcategories. Until new classifications are more widely in use, this report will continue to use the term "partial seizures" and its subcategories.

Generalized Seizures

Generalized seizures are caused by nerve cell disturbances that occur in more diffuse areas of the brain than do partial seizures. Therefore, they have a more serious effect on the patient. They are further subcategorized as tonic-clonic (or grand mal) or absence (petit mal) seizures.

Tonic-Clonic (Grand Mal) Seizures. The first stage of a grand mal seizure is called the tonic phase, in which the muscles suddenly contract, causing the patient to fall and lie stiffly for about 10 to 30 seconds. Some people experience a premonition or aura before a grand mal seizure; most, however, lose consciousness without warning. If the throat or larynx is affected, there may be a high-pitched musical sound (stridor) when the patient inhales. Spasms occur for about 30 seconds to a minute, then the seizure enters the second phase, called the clonic phase. The muscles begin to alternate between relaxation and rigidity. After this phase, the patient may lose bowel or urinary control. The seizure usually lasts a total of two to three minutes, after which the patient remains unconscious for a while and then awakens to confusion and extreme fatigue. A severe throbbing headache similar to migraine may also follow the tonic-clonic phases.
Absence (Petit Mal) Seizures. Absence or petit mal seizures are brief losses of consciousness that occur for 3 to 30 seconds. Physical movement and loss of attention may stop for only a moment. Such seizures may pass unnoticed by others. Small children may simply appear to be staring or walking distractedly. Petit mal may be confused with simple or complex partial seizures, or even with attention deficit disorder. [See In-Depth Report #30: Attention Deficit Hyperactivity Disorder.] In petit mal, however, a person may experience attacks as often as 50 to 100 times a day. About 25% of patients with petit mal develop grand mal seizures. An electroencephalogram (EEG) test that shows a specific brain wave pattern can usually identify these patients.

Click the icon to see a depiction of a tonic-clonic seizure.

Other Seizures

Atonic (Akinetic) Seizures. A person who has an atonic (or akinetic) seizure loses muscle tone. Sometimes it may affect only one part of the body so that, for instance, the jaw slackens and the head drops. At other times, the whole body may lose muscle tone, and the person can suddenly fall. A brief atonic episode is known as a drop attack.