Abstracts

Rationale: The long-term prognosis for cryptogenic partial epilepsy in children remains poorly understood. We compared long-term outcome in a population-based group of children with cryptogenic vs symptomatic partial epilepsy diagnosed between 1980-2004. Methods: Children (1 month through 17 years) who were newly diagnosed with non-idiopathic partial epilepsy between 1980-2004, while resident in Olmsted County, Minnesota were identified through the Rochester Epidemiology Database. Cases with idiopathic partial epilepsy syndromes were excluded. Medical records were reviewed to determine etiology, results of imaging and EEG studies, treatments used, and long-term outcome. Cases were defined as "cryptogenic" if they had a normal neurological exam, were developmentally normal, and had no lesion on neuroimaging, and as "symptomatic" if any of these features was not present. Results: Of 356 children with epilepsy, 210 (59%) were non-idiopathic, localization-related. Of these, 203 (97%) were followed for >12 months (mean followup 159 months, SD 91 months). Seventy (34%) were cryptogenic. Symptomatic etiologies included prior brain insult (51), developmental delay alone (35), malformations of cortical development/tuberous sclerosis (21), mesial temporal sclerosis (7), vascular malformations (6), tumor (4), chromosomal abnormality (4), hypothalamic hamartoma (1) and dual pathology (4). Long-term outcome was significantly better in those with cryptogenic vs symptomatic etiology (intractable epilepsy at last follow-up - 4% vs 32%, p<0.001, seizure-freedom at last followup - 84% vs 61%, p<0.002, medication-freedom at last follow-up - 59% vs 33%, p<0.002). Epilepsy surgery was performed in 15% of symptomatic cases vs none of the cryptogenic cases. Conclusions: One third of childhood non-idiopathic focal epilepsy is cryptogenic. This group has a significantly better outcome than those with a symptomatic etiology, and should be viewed as clinically distinct.