Abstracts

RATIONALE: Patients undergoing anterior temporal lobectomy (ATL) are at risk for material specific memory loss. While memory preservation is likely in those who have good memory contralateral to the resection, there is little data describing memory outcome in patients with poor bihemispheric memory. Our objective was to analyze material specific memory outcome in ATL patients who demonstrated extremely poor memory function with both hemispheres during intracarotid amytal testing (IAT).
METHODS: All patients who underwent ATL and who had pre- and postoperative neuropsychological testing at MINCEP Epilepsy Care were considered for the study (n=354). Patients whose IAT memory score was [lt]40% with each hemisphere were included in the study. Demographic data and seizure outcome were obtained by chart review. Verbal and nonverbal memory were measured using RAVLT (cumulative learning score, post interference recall and delayed recall) and Rey-Osterrieth Complex Figure Test, respectively. Memory decline was defined as [gt]1 standard deviation decrease in postoperative memory score.
RESULTS: Twenty-nine patients (16 female/13 male, 19 left ATL, 10 right ATL) were included in the study (29/354, 8.2%). All patients were left hemisphere dominant for language. MRI results demonstrated normal in 12, MTS in 10 and structural lesion in 7. Seizure outcomes were 14/29 (48%) Engel I, 5/29 (17%) Engel II, 5/29 (17%) Engel III, and 5/29 (17%) Engel IV (average follow-up 3.4 years). Left ATL patients had significant postoperative declines noted on the following RAVLT tests: cumulative learning score, 8/19 (42%) patients; post interference recall, 6/19 (32%) patients; delayed recall, 4/19 (21%) patients. Six (32%) left ATL patients demonstrated postoperative decline on the Rey-Osterrieth Complex Figure Test. Few right ATL patients had verbal or nonverbal memory decline (2/10 patients, all scores considered). Left ATL patients were more likely than right ATL patients to have significant decline on RAVLT cumulative learning score (p= 0.016).
CONCLUSIONS: Approximately one-third of left ATL patients with extremely poor bihemispheric memory testing on IAT demonstrated significant postoperative verbal and nonverbal memory decline. Right ATL patients were significantly less likely than left ATL patients to experience postoperative memory decline. Complete seizure freedom after ATL was noted in slightly less than half of the patients in our study. This data suggests that temporal lobectomy involving the dominant hemisphere in patients with severe bitemporal memory dysfunction carries the risk of further memory decline.
[Supported by: MINCEP[reg] Epilepsy Care]