Abstracts

Rationale: Neuropsychological data has been used in conjunction with VEEG recordings and neuroimaging to help lateralize seizure focus, and it has been previously demonstrated to increase presurgical predictive value with regard to lateralization. However, when the neurologic data are not strongly lateralized, the extent to which this is also reflected in the neuropsychological data has not been studied. The aim of this study was to examine the concordance between neuropsychological data and measures used to lateralize seizure focus, specifically ictal EEG, interictal EEG abnormalities, and brain MRI. Methods: Thirty seven patients (mean age: 31.92, median age: 31.00, range: 45, % female: 48.6%) with a diagnosis of epilepsy who were being considered for resective surgery completed comprehensive presurgical evaluations that included results from 1) ictal VEEG, 2) interictal VEEG (electrographic abnormalities), 3) MRI, and 4) neuropsychological assessment. Results of each of these four diagnostic modalities were coded as "left lateralized," "right lateralized," or "nonlateralizing," regardless of localization. Frequency of concordance was examined using Chi square analyses. Results: Lateralization through neuropsychological data was most strongly concordant with interictal epileptiform abnormalities (χ2 (4, 37) = 16.75, p < .01). In contrast, neuropsychological data was not found to be significantly concordant with either ictal VEEG or neuroimaging, although the former approached significance. Conclusions: These results suggest that interictal activity is exerting a greater effect on neurocognitive functioning than actual seizures and/or structural abnormalities in the brain. The primary goal of epileptologists is to stop seizures in patients with epilepsy, while less emphasis is placed on identification and/or reduction of interictal epileptiform activity. However, given the current findings demonstrating a lateralized association between EEG interictal physiologic dysfunction and decreased performance on neuropsychological testing, epileptologists should consider whether reducing interictal activity should be added to the treatment goals.