Petit mal seizure

Alternative names:

absence seizure; seizure - absence; seizure - petit mal

Definition:

A brain disorder involving temporary disturbance of brain function caused by abnormal electrical activity in the brain nerve cells, characterized by abrupt, short-term lack of conscious activity.

Causes, incidence, and risk factors:

Petit mal seizures occur in 2 out of 1,000 people. They are most common under age 20, usually in children ages 6 to 12. They may occur in combination with other types of seizures.

Typical petit mal seizures last only a few seconds, with full recovery and no confusion. They manifest themselves as staring episodes or "absence spells" during which the child's activity or speech ceases. The child may stop talking in mid sentence or cease walking. One to several seconds later speech or activity resume. If standing or walking a child seldom falls during one of these episodes. "Spells" can be infrequent or very frequent occurring many times per hour. They can interfere with school function and learning. Teachers may interpret these seizures as lack of attention or other misbehavior.

Atypical petit mal seizures begin slower, last longer, and may have more noticeable muscle activity than typical petit mal seizures. There is usually no memory of the seizure.

Up to hundreds of seizures can occur in a person in a single day. They may occur for weeks to months before they are noticed because symptoms commonly occur during quiet rest periods rather that periods of activity.

Transmission of information from nerve cell to nerve cell occurs by an electrochemical process. This process can be detected as electrical activity by an electroencephalograph (EEG). Abnormal patterns of electrical activity are associated with seizures. Petit mal seizures generally present a very characteristic appearance on the EEG.

No cause can usually be found for typical petit mal seizures. No neurologic or other disorders are usually discovered. Atypical seizures may or may not be associated with other neurologic disorders. Causes may be unidentifiable, or identified as congenital brain abnormalities, complications of kidney or liver disease, or brain injuries from trauma or birth complications.