Abstracts

Rationale: While the Wechsler intelligence scales are commonly used in pediatric epilepsy, debate exists about the relative sensitivity of these measures to seizure-related and sociodemographic factors. We examined these relationships in a cohort of higher functioning children with focal epilepsy. Methods: The participants were 110 English speaking children with focal epilepsy referred for a neuropsychological assessment as part of an evaluation for epilepsy surgery. All were administered an age-appropriate Wechsler intelligence scale and had Full Scale IQ (FSIQ) scores > 70 (mean FSIQ = 92.6, SD = 12.8). 51 percent were female with an average age of 12.9 years (SD = 2.99). 65 patients had left hemisphere foci. 46 had right hemisphere foci. A significant VCI/PRI discrepancy was defined as a difference score of 15 points. 24 patients had a large PRI > VCI discrepancy. 8 patients had a significant VCI > PRI discrepancy. Average maternal education was 14 years. A series of stepwise regression analyses was performed to examine the relative contributions of maternal education and seizure-related factors (age of onset, duration of disorder, seizure frequency, and number of antiepileptic drugs) to the FSIQ and the four index scores: Verbal Comprehension (VCI), Perceptual Reasoning (PRI), Working Memory (WMI), and Processing Speed (PSI). Results: Stepwise regression analyses indicated maternal education accounted for the most variance in FSIQ (< .000), VCI (p <.000), and WMI (p =.002) with the number of AEDs explaining significant additional variance in each of index. Only maternal education accounted for variance in PRI (p = .003). Number of AEDs accounted for the most variance in PSI (p <.000) with maternal education explaining additional variance. Neither left nor right hemisphere focus was associated with VCI or PRI. In children with large PRI > VCI discrepancies, 71 percent had a left focus and 29 percent had a right focus. Of those with VIQ > PIQ discrepancies, 87.5 percent had a left focus and 12.5 percent had a right focus. Stepwise regression analysis indicated that VCI > PRI discrepancy was associated with higher maternal education (p =.015) but not laterality of seizure focus. Higher VCI than PRI was associated with higher maternal education. Conclusions: The Wechsler indices are differentially sensitive to seizure-related and sociodemographic factors in higher functioning pediatric epilepsy patients. Maternal education was the most powerful predictor intelligence test performance. Slower information processing, however, was associated with number of AEDs. Wechsler test profiles should not be used to infer seizure laterality as children with VCI/PRI discrepancies in either direction were more likely to have a left hemisphere focus.