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Memory Outcomes Following Selective Versus Nonselective Temporal Lobe Removal: A Systematic Review


Fady Girgis, University of Calgary, Foothills Hospital, 12th Floor, 1403 29th St. NW, Calgary, AB, Canada T2N 2T9; e-mail:


The surgical removal of brain tissue for the treatment of temporal lobe epilepsy can be either nonselective, as with an anterior temporal lobectomy (ATL), or selective, as with a selective amygdalohippocampectomy (SAH). Although seizure outcomes are similar with both procedures, cognitive and memory outcomes remain a matter of debate. This study aims to evaluate current evidence with regard to memory outcomes in ATL and SAH. A systematic literature review was conducted combining the search term “memory” with each of the search terms “temporal lobe epilepsy surgery,”“anterior temporal lobectomy,” and “amygdalohippocampectomy,” with articles from 1995 to November 2011 included. A total of 27 articles met the inclusion criteria. These were compared using statistically significant outcomes from validated neuropsychological tests assessing verbal and visual memory. Analysis revealed that verbal memory decline is significantly associated with left ATL, while visual memory decline is significantly associated with right ATL. Evidence for memory outcomes in SAH, however, was inconclusive, as studies failed to show a consistent pattern with regard to type of memory decline and side of surgery. Surgery of the left temporal lobe relates to verbal memory decline, while surgery of the right temporal lobe relates to visual memory decline. Despite this generality, however, further research is necessary to determine the superiority of selective versus nonselective temporal surgical methods in regard to these memory outcomes and their effects on learning.