Abstracts

Rationale: The Wechsler Adult Intelligence Scale-4th Edition (WAIS-IV) is a relatively new tool in the presurgical workup in temporal lobe epilepsy (TLE). Although the focus in neuropsychological has been to study lateralization of memory capacity following TLE, it is not limited to memory capacity but can also involve intellectual functions (Saling, 2009). A previous study (Kim et al., 2003) showed that patients with left TLE had lower scores on the Verbal Comprehension factor, whereas patients with right TLE obtained lower scores on the Perceptual Organization factor. To our knowledge, no study has reported WAIS-IV results in patients with TLE. The present study investigates the factor structure of the WAIS-IV in a TLE sample and compares patients with left versus right temporal lobe epilepsy on the WAIS-IV. Methods: Ninety-five patients with intractable TLE completed the core WAIS-IV subtests (53 right TLE and 42 left TLE). Mean age and education were 39.51 13.58 and 13.11 2.34 years, respectively. The mean age of diagnosis was 22.11 15.40. An exploratory factor analysis of the core subtests from the WAIS-IV was conducted. A secondary analysis was also performed wherein the number of factors to be extracted was set to 4 to match the current WAIS-IV structure. We then compared left and right TLE on WAIS-IV performance using two separate 2 2 (Intelligence Type Seizure Laterality) analyses of variance (ANOVA); one involving the Verbal Comprehension (VCI) and Perceptual Reasoning (PRI) Indices from the WAIS-IV and one involving the resulting factors of the exploratory factor analysis.Results: The first analysis produced two factors. The first factor (VC) contained subtests from the VCI and accounted for 35.31% of the total variance. The second factor (Non-verbal Intellectual) contained subtests from the PRI, Working Memory (WM), and Processing Speed (PS) Indices and accounted for 31.54% of the total variance. The second analysis resulted in the expected factors. The VC, PR, WM, and PS factors accounted for 25.45%, 21.54%, 16.52%, and 18.47% of the variance, respectively. In the first ANOVA, the left versus right TLE were not significantly different when comparing their VCI, F(1, 93) < 1, and PRI scores, F(1, 93) < 1. Similar results were obtained in the second ANOVA where the left versus right TLE patients were not significantly different when comparing their performance on the VC Factor, F(1, 93) < 1, and Non-verbal Intellectual Factor, F(1, 93) <1.Conclusions: Two factors emerged from the factorial analysis, which were consistent with the subtests in the VCI (VC Factor) and the subtests in the PRI, WMI, PSI (Non-verbal Intelligence Factor) from the original WAIS-IV normative studies. Moreover, no significant differences were found when comparing left and right TLE on their VCI and PRI scores. These findings suggest that the WAIS-IV is limited in its ability to determine lateralization of left and right TLE.