Improvements in memory function following anterior temporal lobe resection for epilepsy

Background: While up to a third of patients may experience a decline in memory following an anterior temporal lobe resection (ATL) for epilepsy, between 10 and 20% may experience a postoperative improvement in function. The aim of this study was to examine the preoperative characteristics of these patients. Methods: Logistic regression analyses were used to determine which variables influenced postoperative memory improvement following ATL on standardized memory tests in 237 patients with unilateral hippocampal sclerosis (105 right; 132 left). Results: A total of 22% of the right ATL and 9% of the left ATL group demonstrated a significant postoperative improvement in verbal learning. A total of 9% of the right ATL and 16% of the left ATL group demonstrated a significant postoperative improvement in visual learning. In the R ATL group, postoperative improvements in verbal learning were associated with poor preoperative verbal learning, a shorter duration of epilepsy, higher scores on the visual learning task, and an older age at the time of surgery. In the L ATL group, postoperative improvements in visual learning were associated with poor preoperative visual learning, a shorter duration of epilepsy, and a higher IQ. Postoperative improvements in memory functions associated with the ipsilateral temporal lobe were not associated with demographic or epilepsy-related variables. Conclusions: Memory deficits normally associated with the function of the contralateral temporal lobe in patients with unilateral hippocampal sclerosis may improve postoperatively in patients with a shorter duration of epilepsy and the cognitive capacity to develop compensatory strategies. Neurology (R) 2008; 71: 1319-1325