Abstracts

Absence seizures are a form of generalized epilepsy commonly seen in children. The clinician is often presented with a patient whose EEG does not fit the typical absence pattern. The purpose of this study is to more closely examine both typical and atypical absence variants and their outcome. A retrospective chart review was performed on children diagnosed with absence epilepsy over the past five years at the University of Alberta. One hundred and seven patients were reviewed. Patients were classified with typical or atypical absence seizures following ILAE criteria and EEG characteristics. Clinical seizure characteristics, MRI, initial response to treatment and outcome were examined. Seizure characteristics were similar in both the typical and atypical absence groups. Aura, complex automatisms, changes in tone, and incontinence were seen in both groups, although status epilepticus was found only in the atypical group. Associated co-morbid conditions such as Attentional Deficit Hyperactivity Disorder, learning disorders, and enuresis were found equally in both groups. Developmental delay was found more often in the atypical group. Eighty-three percent of the typical group responded to an initial antiepileptic drug (either valproic acid or ethosuximide) while only 51% of the atypical group had complete seizure control. Remission at 2 years, however, was similar between groups, with 87% of the typical group and 71% of the atypical group becoming completely seizure free. Absence seizures in childhood, both typical and atypical, share similar clinical and electroencephalographic features and appear to be part of a continuum. Associated co-morbid features such as ADHD, learning disorders, and developmental delay are also seen in both groups. The outcome for both types is excellent, although the atypical variants may be initially more difficult-to- control.