AbstractsPsychology

This study took place at the National Center for Epilepsy (SSE) Norway and one discusses the effects on verbal memory after right or left anterior temporal lobe (ATL) surgery for epilepsy. It is suggested that a resection in the left temporal lobe will reduce the two years postoperative performance on verbal memory tasks, compared to resection in the right temporal lobe. Different areas in the left temporal lobe mediate verbal memory, and memory is seen as a multifaceted system, consisting of encoding, storing and retrieving. Memory impairment or improvement can exist in any of these stages. Subjectives: All 50 out of 69 subjects from a clinical database who had undergone a left or right standard anterior temporal lobe resection at the SSE. There were 9 males and 15 female in the left ATL group and 19 male and 7 female in the right ATL group. The mean age at surgery is 35 years. Language: The Wada test confirmed all subjects to be left hemisphere dominant for speech. Test: Verbal learning and memory was determined by the method of The California Verbal Learning Test (CVLT or CVLT-II), further referred to as CVLT. The CVLT was administered shortly before surgery and 1-2 years follow up. IQ: The full scale iq scores (FIQ) and verbal iq scores (VIQ) scores were determined by the method of The Wechsler Adult Intelligence Scale, Norwegian form (WAIS-III) or The Wechsler Short Abbreviated Intelligence Scale, Norwegian form (WASI). The mean FIQ score is 89.6. Results: No significant preoperative differences in verbal memory were observed between groups, but there were significant postoperative CVLT changes in both groups, on the learning score and on the long delayed free recall trial respectively. Whereas a significant decrease was observed in the left ATL group, improved performance was seen in the right ATL group. Totally, there were no significant change in pre and post- operative performance due to test results alone. However, the results show effect of interaction between operation and lateralization concerning Total 1-5 trials and long delayed free recall. Conclusions: The main findings are in line with the hypotheses that memory change will take place after anterior temporal lobe resection. Difference in test performance is seen as an interaction effect of surgery (removal of eloquent tissue) and lateralization (left or right hemisphere). Postoperative verbal memory decline concerned the left ATL group and postoperative improvement concerned the right ATL group. This confirms previous findings, showing a greater vulnerability for verbal memory to left ATL surgery. The results suggest reserve capacity of the contra lateral medial structures of the temporal lobes or the reserve capacity of the remnant medial structures.