MRI HIPPOCAMPAL VOLUMES AND MEMORY FUNCTION BEFORE AND AFTER TEMPORALLOBECTOMY

We investigated the relationship between preoperative MRI hippocampal volumes and clinical neuropsychological memory test data obtained befo re and after temporal lobectomy and amygdalohippocampectomy for intrac table epilepsy in 44 left (LTL) and 36 right (RTL) temporal lobectomy patients. In LTL patients, the difference (right minus left hippocampa l volume) between hippocampal volumes (DHF) was significantly (p < 0.0 01) correlated (r = 0.61) with postoperative verbal memory change as m easured by a delayed memory percent retention score from the Wechsler Memory Scale-Revised, Logical Memory subtest. DHF was also positively associated with postoperative memory for abstract geometric designs in LTL patients (r = 0.49, p < 0.005). Resection of a relatively nonatro phic left hippocampus was associated with poorer verbal and visual mem ory outcome. In RTL patients, larger right adjusted (for total intracr anial volume) hippocampal volume was associated with decline in visual -spatial learning, but not memory, following surgery. MRI hippocampal volume data appear to provide meaningful information in evaluating the risk for memory impairment following temporal lobectomy.