Serial cognitive testing in temporal lobe epilepsy: longitudinal changes with medical and surgical therapies

Cognitive testing was repeated at intervals ranging from 1 to 8 years in 47 adult patients with temporal lobe epilepsy (TLE). Each patient underwent standardized batteries, including the Wechsler Adult Intelligence Scale, Revised (WAIS-R), and Wechsler Memory Scale (WMS). Both surgically treated and nonsurgical patients were examined. The nonsurgical group underwent serial testing for clinical indications, usually for complaints of memory dysfunction. Longitudinal testing could not verify any mean deterioration of intellect or memory in this group; variance over time was similar to test-retest norms in healthy controls. WAIS-R scores before and after resection in the surgical group were similar to our serial WAIS-R data in nonsurgical patients. When we divided surgical patients according to side of epileptogenesis, we noted the expected differences in verbal and visual memory. Right-sided surgery patients improved significantly in Full-Scale IQ (FSIQ) and tended to improve in logical memory on postoperative testing. Patients undergoing left resections had no retest improvement and tended to show decrease in several measures of verbal memory. Our findings should stimulate continued investigation into the natural history of lateralized memory and intellectual function in epilepsy, particularly to clarify long-term cognitive outcome in nonsurgical patients.