absence seizure, an epileptic seizure characterized by a sudden, momentary loss of consciousness. Occasionally it is accompanied by minor myoclonus of the neck or upper extremities, frequent blinking, slight symmetric twitching of the face, or loss of tonus. Seizures usually occur many times a day without a warning aura and are most frequent in children and adolescents, especially at puberty. Children often outgrow them. The patient experiencing a typical seizure has a vacant facial expression and ceases all voluntary motor activity; with the rapid return of consciousness, the patient may resume conversation at the point of interruption without realizing what occurred. During and between seizures, the patient’s electroencephalogram shows 3-Hz spike-and-wave discharges. Anticonvulsant drugs used to prevent absence seizures include ethosuximide and valproic acid. Also called absentia epileptica, petit mal seizure. See also epilepsy.
