A population-based study of long-term outcome of epilepsy in childhood with a focal or hemispheric lesion on neuroimaging

Abstract

Purpose: To evaluate long-term seizure outcome in children with epilepsy and a focal or hemispheric neuroimaging abnormality.

Methods: All children (<18 years and residing in Olmsted County, Minnesota) with new-onset epilepsy diagnosed between 1980 and 2004 and a single focal lesion on neuroimaging were identified by review of the Rochester Epidemiologic Project database. Outcomes were divided into three categories: (1) seizure freedom for 1 or more years at last follow-up, (2) ongoing seizures but not medically intractable epilepsy, and (3) medically intractable epilepsy or undergoing epilepsy surgery. We also evaluated the proportion who achieved seizure control without surgical intervention and whether lesion type predicted intractability.

Key findings: Of the 359 children with newly diagnosed epilepsy, 37 (10%) had a focal or hemispheric lesion on neuroimaging. Median age of diagnosis was 89 months (25th percentile 26 months, 75th percentile 142 months) and at follow-up was 137 months (25th percentile 95 months, 75th percentile 211 months). Eighty-three percent of children with malformations of cortical development, 67% with mesial temporal sclerosis, 33% with encephalomalacia, and 50% with vascular malformations had intractable epilepsy at follow-up or underwent resective surgery for medically intractable epilepsy. Among the different etiologies, presence of encephalomalacia predicted the lowest likelihood of medical intractability or undergoing surgery (p < 0.01). At final follow-up, 24 (65%) of our entire cohort was seizure free. Following surgery, seizure freedom was achieved in 80% with mesial temporal sclerosis, 67% with encephalomalacia, 67% with vascular malformation, and 50% with malformations of cortical development. There was no statistically significant difference between the different etiologies on neuroimaging and seizure freedom after surgery. Twelve children (32%) achieved seizure freedom with medical management alone.

Significance: Focal lesions on neuroimaging confer a high risk of medical intractability among children with new-onset epilepsy. However, 32% of this cohort achieved seizure remission with medical management alone, including 58% with encephalomalacia and 33% with mesial temporal sclerosis.