Significant discrepancies between immediate and delayed WMS-III indices are rare in temporal lobe epilepsy patients

Initial factor analysis of Wechsler Memory Scale-Third Edition (WMS-III) standardization data resulted in a five-factor model that included separate immediate (IMM) and delayed (DEL) memory factors for auditory (AUD) and visual (VIS) memory. However, recent factor analyses that revealed three factors--AUD, VIS, and working memory--were discovered to be more accurate. Continued use of separate WMS-III IMM and DEL indices has been recommended because future studies with clinical groups might support this distinction. Data from this investigation of 88 temporal lobe epilepsy (TLE) patients suggested separate IMM and DEL WMS-III indices are not necessary in this population. Results were as follows: 1) There was no significant difference between the IMM and DEL indices for AUD or VIS memory. 2) The percentage of individuals with a significant difference between the IMM and DEL indices (IMM minus DEL >11 or <-12) was similar for our TLE group and the standardization sample. 3) The mean percent retention standard score (SS) was at the average level for the four memory subtests, and for each subtest only about 10% of the TLE patients had impaired scores. 4) Hippocampal volumes correlated significantly with both IMM and DEL indices. These data suggest that combining the appropriate WMS-III IMM and DEL memory subtest scores to form AUD and VIS memory indices is appropriate for TLE patients.