Abstracts

Rationale: How epilepsy resolves is an unexplored research area.  Yet, this transition from epileptic state back to normal is a common occurrence in most pediatric epilepsies. To study this phenomenon, we selected patients with childhood absence epilepsy (CAE), a common, homogeneous epileptic syndrome with a self-limited course. In this initial study, we wanted to know what EEG changes occurred before the final disappearance of their seizures/epilepsy. Methods: Patients were selected that met standard criteria for childhood absence epilepsy. They were followed progressively with serial, biannual EEG over the course of their disorder.  Both routine and 24-hour continuous video-EEG monitoring were used to ensure comprehensive review of both wakefulness and sleep.  Resolution of epilepsy was defined as seizure control for 2 years on standard anti-epileptic drugs and disappearance of the classic 3 Hz spike and wave discharge. Results: We studied 22 CAE patients. Their ages ranged from 9-18 years (mean= 14.3) at the time of their final EEG.  Patients were treated with ethosuximide (n=16) or valproate (n= 6) and treatment duration ranged from 2-6 years (mean= 4.6). All patients demonstrated hyperventilation-induced staring spells and generalized 3 Hz spike and wave discharges on their initial EEG. After 2 years of treatment, local and regional EEG changes were noted. First, bursting activity decreased in duration and frequency during wakefulness. Later, frontal spikes were reduced in size. Residual frontal activity became single bifrontal sharp waves with little generalization. Separately, isolated, often asynchronous, central (C3/C4) sharp waves became more prominent during sleep, also with weak generalization. Sometimes rhythmic occipital sharp wave activity was seen.  Conclusions: Childhood absence epilepsy resolves over 2-3 years in a staged, multifocal manner.  Shrinking epileptic activity is shown by decreased daytime bursting and the appearance of isolated frontal> central> occipital activity suggest changes in selective neuronal pathways. This work provides the first step in understanding the nature of epiilepsy resolution in a common epileptic disorder. A model to describe these network changes is being developed. Funding: No funding