Abstracts

Reliable change index scores (RCIs) have been applied to assessment measures to determine expected differences in scores on the same test attributable to test-retest practice effects and error. RCIs permit evaluation of reliably meaningful changes in test scores after an intervention, such as epilepsy surgery. Although widely used for adult measures (e.g., WAIS-III and WMS-III), RCI methodology has not been applied to examine memory and intellectual functioning in one group of children after epilepsy surgery., As a part of neuropsychological evaluation completed prior to and after epilepsy surgery, the Children[apos]s Memory Scale (CMS) was administered to 63 children 5 to 15 years of age (x=10.74, SD=2.87). The Wechsler Intelligence Scale for Children-Third Edition (WISC-III) was administered to 55 of them ([underline][gt][/underline]6 years). Most were right handed (86%), 34 had left hemisphere surgery and the number of males (30) and females (33) did not differ significantly. Most had temporal (n=36) or frontal (n=14) resections.
Practice adjusted RCIs for the CMS and WISC-III were calculated corresponding to the 90% confidence interval using information from the standardization samples. The standard error of measurement (SEM) and test-retest means were used to calculate the standard error of difference (SED). Change scores were calculated for all CMS and WISC-III indexes and subtests. RCIs were used to determine whether participants showed reliably meaningful changes (gain or decline) or no change following surgery. Chi-square analysis was used to determine significance., In the absence of any effect of epilepsy or epilepsy surgery, when applied to this sample, about three (5%) participants would be expected to show an improvement, three (5%) to show a decline and 56 (CMS) or 49 (WISC-III) to maintain stable scores. Many more participants than expected posted declines in overall memory (55%) and IQ (40%) scores, yet more participants than the expected 5% had improved CMS Visual Delayed scores (8%), Verbal Delayed scores (11%) and Delayed Recognition scores (19%)., Significantly more variability than expected was observed in CMS and WISC-III change scores produced by children with medically-refractory epilepsy tested pre- and post-surgery. RCIs for CMS and WISC-III index and subtest scores are provided to serve as guidelines for evaluating change. Assumptions regarding the relative contributions of ongoing epilepsy, use of medication or surgery to changes in memory or IQ cannot be made. Further studies including non-surgical epilepsy patients tested twice over the same interval will be necessary to estimate the unique contribution of surgery to memory and IQ change.,