Abstracts

Rationale: Patients with intractable seizures are assumed to be at risk for a decline in their cognitive abilities but there have been few longitudinal studies in the pediatric epilepsy population. Clear interpretation of existing studies is compromised because the second assessment is often necessitated by a decline in functional status or continued school problems. Furthermore, most have relied on IQ scores and measures of academic skills may be more sensitive to changes in cognitive ability. Methods: This study included 15 pediatric patients who received a neuropsychological assessment as part of their evaluation for epilepsy surgery. Each of the patients had been previously tested. The average time between the two assessments was 3.8 years with a range of 1 to 8 years. The average age at the time of the first assessment was 10.2 years. 53% of the patients had temporal lobe foci and 53% had secondary generalization. IQ scores and scores on measures of reading, math and spelling from the two time points were compared with paired t-tests. A follow-up examination of the characteristics of a subgroup of these patients employed t-tests for independent groups. Results: Analyses revealed a significant decline in IQ scores between the two time points (p <.01) but did not reveal a significant decline in academic scores. An examination of change scores across individual patients revealed a bimodal distribution. Four patients experienced a dramatic change in IQ scores (X=20.75 points, SD=5.62)while the other 11 patients exhibited little change (X=2.27, SD=3.10). The group who experienced the decline in IQ scores also exhibited a more significant decline in scores on academic tests. The group who declined could not be distinguished from the group who did not on the basis of site of seizure focus, seizure frequency, secondary generalization of seizures, age of onset, time between the two assessments, age or level of intellectual functioning at the first time point.Conclusions: The findings from this study suggest that a subset of children with intractable seizures are at risk for a significant decline in cognitive and academic abilities. The patients in this study who declined could not be distinguished from those who did not on the basis of any obvious clinical characteristics but future studies may help identify specific risk factors.