Postoperative hippocampal remnant shrinkage and memory decline - A dynamicprocess

Background: The severity of postoperative memory decline in unilateral temp oral lobectomy patients has been associated both with the extent of hippoca mpal resection and MRI measures of preoperative hippocampal volume. Serial MRI of the hippocampal remnant suggest that further volume loss occurs in t he immediate postoperative period. For the majority of patients, this proce ss appears to stabilize within the first 3 months. The authors examined the relationship between the dynamic volume of the hippocampal remnant and pos toperative memory decline. Method: Seventeen adult temporal lobectomy patie nts (nine, left; eight, right) underwent a full neuropsychological assessme nt and a volumetric MRI scan preoperatively and 3 months postoperatively. E xamination of the posterior hippocampal remnant on the postoperative scan r evealed volume loss in this segment compared to the identical segment preop eratively in 16 of 17 cases. Spearman's correlations were used to examine t he relationship between postoperative memory decline (postoperative - preop erative memory scores) and the postoperative/preoperative hippocampal remna nt volume ratio. Results: The volume of the hippocampal remnant left in sit u was significantly correlated with postoperative memory change. Patients w ith smaller remnant volumes demonstrated more postoperative memory decline than those with larger remnants. In addition, extensive hippocampal remnant shrinkage was associated with postoperative memory decline in both the rig ht and left temporal lobectomy groups. Conclusions: The absolute volume and subsequent volume loss in the hippocampal remnant following surgery can in fluence postoperative memory change. These findings suggest that postoperat ive processes should be considered in addition to preoperative pathology an d surgical factors in the prediction of postoperative memory change.