Diagnosis and treatment of absence seizures
Absence seizures are characterized by a brief, blank stare. Such seizures occur suddenly, without an aura, and likewise end suddenly, without mental confusion. They may be associated with mild clonic movements, an increase or decrease in postural tone, or automatisms. The ictal electroencephalogram (EEG) reveals generalized spike-and-wave discharges, usually at 3 Hz, though the interictal EEG is usually normal. Seizures usually begin between five and 15 years of age and usually subside with adulthood. Half the patients have a history of one or more generalized tonic–clonic seizures, which may precede or follow the onset of absence seizures. One third have a family history of seizures. Ethosuximide is the preferred treatment in individuals who have absence seizures alone, while valproic acid is preferred for those with a history of generalized tonic–clonic seizures. Once the dose is adjusted to provide an effective trough drug level, nearly all seizures can be completely (or at least satisfactorily) controlled.