Absence seizure

A generalized seizure with abrupt onset and offset of altered awareness which can vary in severity (see specific syndromes). Memory for events during the seizures is usually impaired although there may be some retained awareness particularly for adolescents. Clonic movements of eyelids, head, eyebrows, chin, perioral or other facial parts may occur.


Excessive and persistent worry that does not go away and may start to interfere with someone’s ability to complete daily activities.

Atonic seizure

An epileptic seizure characterized by sudden loss of muscle tone; may cause the head to drop suddenly, objects to fall from the hands, or the legs to lose strength, with falling and potential injury; usually not associated with loss of consciousness.

Atypical absence seizure

A staring spell characterized by partial impairment of consciousness; often occurs in children with the Lennox-Gastaut syndrome; the EEG shows slow (less than 3 per second) spike-and-wave discharges.


A warning before a seizure; a simple partial seizure occuring within seconds before a complex partial or secondarily generalized tonic-clonic seizure, or it may occur alone; also a warning before a migraine headache.