Abstracts

RATIONALE: We evaluated whether Wada Test memory scores were influenced by patterns of languge laterality. We also compared scores for patients with a unilateral anterior temporal lobe seizure focus and patients with a focus outside the anterior temporal lobe. Our expectation was that language laterality group would have an influence on memory scores, and that patients with a focus outside the anterior temporal lobe would not show a memory asymmetry.
METHODS: There were 336 patients with an anterior temporal lobe focus and 59 patients with a focus outside the anterior temporal lobe who had useable data from each hemisphere. Memory scores were derived from post-recovery recognition testing, and adjusted for guessing ( {%correct presented under drug + %correct rejected foils} / 2). Language laterality was based on clinical characteristics, and patients were assigned to one of five language categories (L Only, L[gt]R, L=R, R[gt]L, R Only). Comparisons were made using MANOVA and post-hoc tests, as needed.
RESULTS: Overall, patients with a right anterior temporal lobe focus had better memory scores when using their left hemisphere, and patients with a a left anterior temporal lobe focus had better memory scores when using their right hemisphere, though the asymmetry was smaller for the left group than the right group. When classified by language laterality, it was clear that the memory scores were affected by language laterality, as the pattern for patients with right-ward speech laterality was the reverse of patients with left-ward speech laterality. The pattern of memory asymmetry for patients with a seizure focus outside the anterior temporal lobe did not differ from those with an anterior temporal lobe focus.
CONCLUSIONS: These results indicate that a memory asymmetry can be demonstrated when comparing the seizure focus hemisphere to the non-seizure focus hemisphere, using post-recovery recognition memory scores. However, even though these scores should theoretically avoid the influence of languge disruption that occurred during the active phase of the amytal, post-recovery scores were clearly influenced by whether language was or was not affected. The similar pattern seen for anterior temporal lobe focus patients and those with a focus outside the anterior temporal lobe suggests that the memory asymmetry found in Wada Testing may reflect processing in pathways beyond the anterior temporal lobe. These results should also suggest caution in rejecting candidates for temporal lobectomy based solely on a low score or reverse asymmetry, particularly in patients with right-ward language laterality.