Abstracts

RATIONALE: In recent years, risk of material specific verbal memory decline following dominant temporal lobectomy (TL) has led to selective cases of surgical sparing of the hippocampus in our program. This study examines the memory outcome of these patients. METHODS: The subjects were 36 dominant TL patients. Twenty-eight underwent TL with resection of the hippocampus, while the hippocampus was spared in 8 cases based on a combination of risk factors including absence of MTS, intact dominant hemisphere memory performance in the intracarotid amobarbital procedure, later age of seizure onset and baseline verbal memory test performance. The two groups were compared on measures of the verbal Selective Reminding Test (vSRT) using pre to postoperative difference scores with a univariate ANOVA which adjusted for baseline delayed recall performance. The two groups did not differ in age, IQ or gender. RESULTS: Preoperative performance on the vSRT was equivalent for the two groups with mean scores falling in the mildly impaired range. Postoperatively, patients with sparing of the hippocampus showed no significant change in memory performance while patients who underwent hippocampal resection demonstrated significantly greater decline on the long-term storage (p<.03) and delayed recall (p<.002) vSRT measures. CONCLUSIONS: These data suggest that sparing of the hippocampus in dominant TL results in preservation of verbal memory. This more conservative surgical procedure in cases at high risk for postoperative memory decline is neuropsychologically justified. These data will be discussed in relation to surgical selection criteria and postoperative seizure outcome.