Abstracts

Rationale: Pre-surgical neuropsychological assessment of temporal lobe epilepsy (TLE) patients can be informative and guide clinical decision-making because of the increased risk of memory and language impairment after left temporal lobe resections. One of the most popular and well-studied memory measures, the Wechsler Memory Scale (WMS), has recently been revised (i.e., Wechsler Memory Scale - Fourth Edition; WMS-IV). While the WMS-IV may be used to assess pre-surgical lateralization of function, its clinical utility and incremental validity have been questioned. We analyzed the WMS-IV as well as more commonly used cognitive measures, the Rey Auditory Verbal Learning Test (RAVLT) and Rey-Osterrieth Complex Figure Test (ROCFT), to assess lateralization differences in memory between left and right TLE patients. Methods: Neuropsychological testing was administered to pre-surgical TLE candidates. Participants: A total of 25 participants met criteria for this study which included EEG and MRI evidence of seizure focus. There were 11 left TLE (LTLE) and 14 right TLE (RTLE) patients. Variables/Measures: Participants completed comprehensive neuropsychological evaluations which included the WMS-IV, RAVLT and RCOFT. Results: Intelligence, education, and age did not differ between LTLE and RTLE groups. ANOVA found that WMS-IV primary indices (Auditory Memory, Visual Memory, Immediate Memory, and Delayed Memory) were similar for each group. In contrast, a subtest analyses found that LTLE patients performed significantly worse than RTLE patients on the Logical Memory I (p=0.030) and Logical Memory II (p=0.034) subtests, which are immediate and delayed measures of prose memory. LTLE patients also performed significantly worse than RTLE patients on the Immediate Recall (p=.036), Delayed Recall (p=0.042), and Recognition (p=0.041) trials of a list-learning measure (RAVLT). During the recognition task, LTLE patients also made significantly more false positive (p=0.23) and false negative (p=0.006) errors. No significant lateralizing differences were found on a test of visual memory (ROCFT). Conclusions: These data suggest that the WMS-IV and ROCFT have limited clinical utility when differentiating between left and right TLE dysfunction in pre-surgical candidates. In contrast, the Logical Memory subtests of the WMS-IV were sensitive to laterality of the seizure focus. As found in previous research, several scores from the RAVLT demonstrated clear clinical utility and sensitive to left temporal dysfunction. While the changes in the updated WMS-IV have promise to better lateralize right TLE dysfunction, these data failed to support such a claim. Future investigations should be pursued in order to assess the validity of WMS-IV for pre-surgical TLE patients.