The effects of cognitive rehabilitation on memory outcome after temporal lobe epilepsy surgery

Epilepsy surgery is a valuable treatment option for patients with pharmacoresistant epilepsy, but seizure freedom is often achieved at the cost of cognitive impairments caused by surgery. The aim of this study was to investigate the short-term effects of cognitive rehabilitation on memory outcome after temporal lobe epilepsy surgery.

Two groups of patients who underwent temporal lobe resection, one followed (n=55) and one not followed (n=57) by postoperative rehabilitation, were evaluated with respect to memory and attention before and 3 months after temporal lobe surgery. The groups came from different epilepsy centers, but were largely matched with respect to age, sex, type of surgery, and seizure outcome.

After surgery, 78% of the patients were seizure-free. Repeated-measures MANOVA revealed a significant "side x surgery" effect on verbal recognition and a "rehabilitation x surgery" effect on verbal learning and recognition. There were no effects for loss in verbal delayed recall or figural memory. Detailed analyses indicated gains as a result of rehabilitation, particularly after right temporal lobe surgery. Attention generally improved. The risk of manifesting losses in verbal memory was about four times higher without than with rehabilitation.

Rehabilitation can counteract the verbal memory decline that is normally seen after temporal lobe resection. Its positive effects were evident particularly with respect to the more cortically associated aspects of verbal learning rather than to the mesial aspects of long-term consolidation/retrieval. Figural memory was not affected at all, and attention improved independent of rehabilitation. Interestingly, left temporal lobe-resected patients, who were most in need of an efficacious rehabilitation, profited less than right temporal lobe-resected patients, indicating that left-sided surgery may reduce the capacity needed for efficient training of verbal memory. Thus, rehabilitation has a positive effect on memory outcome, but its usefulness for risk groups and the question of whether training should be performed after or possibly before surgery are debatable. Further research should also address different interventions, longer-term outcome, and the carryover effects on everyday functioning.