Lateralizing memory function in temporal lobe epilepsy : an investigation of the meaning and utility of the Wechsler Memory Scale, third edition

dc.contributor.authorWilde, Nancy Jean.en_US
dc.contributor.supervisorStrauss, Esther.en_US of Psychologyen_US
dc.description.abstractThe Wechsler Memory Scale (WMS) is the most extensively used battery for memory assessment of adults. The third edition of the WMS (WMS-111) represents a substantial revision of previous versions. Accordingly, issues of validity of the revised instrument need to be addressed. The purpose of these studies was to contribute to the validation of the scale in the assessment of patients with temporal lobe epilepsy WE). An important role of the neuropsychological evaluation in TLE is to aid in the localization and lateralization of dysfunction. This is based on the premise that the temporal lobes are specialized for the acquisition of material-specific information, with dysfunction in the left and right mesial temporal regions being associated with verbal and nonverbal memory impairment, respectively. Since the WMS is utilized by the vast majority of epilepsy centres, evaluation of its meaning and utility in this population is essential. In Study 1, the utility of the WMS-I11 in detecting lateralized impairment was examined in a sample of patients with left (n = 55) or right (n = 47) TLE. Methods of analysis included evaluation of group means on the various indexes and subtest scores, the use of ROC curves, and an examination of Auditory-Visual Index discrepancy scores. The Auditory- Visual Delayed Index difference score appeared most sensitive to side of temporal dysfunction, although patient classification rates were not within an acceptable range to have clinical utility. The ability to predict laterality based on statistically significant index score differences was particularly weak for those with left temporal dysfunction. The use of unusually large discrepancies led to improved prediction; however, the rarity of such scores limits their usefulness. ill In Study 2, five competing models specifying the factor structure underlying the WMS- 111 primarysubtest scores were evaluated in a large sample of patients with TLE (N = 254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory, and a nested- more parsimonious- 2-factor model of working memory and general memory. The results suggested that specifying a separate visual memory factor provided little advantage for this sample- an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions. These findings add to a growing literature which suggests that the WMS-I11 has little utility in detecting lateralized dysfunction in TLE. This has important implications for the preoperative assessment of epilepsy patients.en_US
dc.subject.lcshWechsler Memory Scaleen_US
dc.subject.lcshTemporal lobe epilepsyen_US
dc.titleLateralizing memory function in temporal lobe epilepsy : an investigation of the meaning and utility of the Wechsler Memory Scale, third editionen_US


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