Verbal and Visual Memory Index Discrepancies From the Wechsler Memory Scale-Revised: Cautions in Interpretation

The present study examined the clinical utility of the Wechsler Memory Scale-Revised (WMS-R) Verbal and Visual Memory Indexes to predict laterality of previous temporal lobectomy (TL) in 13 left (L; 7 men, 5 women) and 20 right (R; 11 men, 9 women) patients. Three verbal-visual index discrepancy criteria were used. Of the 16 patients with difference scores of at least 16 points (least conservative criterion), 9 had index discrepancies that incorrectly identified resection laterality (i.e., Verbal Memory Index decreased relative to Visual Memory Index in RTL patients). Five of 11 patients with index discrepancies of 21 or more points were incorrectly classified. Only 1 of 4 patients was incorrectly classified using a 29-point discrepancy criterion, although 2 RTL patients had discrepancy scores of 28 points in the incorrect direction. Consequently, users of the WMS-R are cautioned against inferring laterality of lesion on the basis of the Verbal and Visual Memory Indexes alone.