Cognitive outcomes of different surgical approaches in temporal lobe epilepsy

Epilepsy surgery is a successful treatment option for pharmacoresistant focal symptomatic epilepsies. However, cognitive impairment is very common in epilepsy patients and may be negatively or positively affected by surgery. Amidst the long-standing discussion of whether a particular surgical approach for temporal lobe epilepsy patients may be superior with regards to seizure control, a recent meta-analysis indicated that this is the case for more extended resections. Larger temporal lobe resections, however, raise concerns that more unaffected and functional tissues may be involved, thus causing worse cognitive outcome. This review is based on published reports collected over a long period, with changing diagnostics and surgical methods, and focuses mainly on the experiences of one epilepsy centre. The review highlights the effects of standard versus selective surgery, the different surgical approaches in selective surgery, determinants other than surgery which may affect cognitive outcome, and the methodologically-important question of outcome assessment and how neuropsychological test selection may bias the result. Overall, from a neuropsychological point of view, individual and selective surgery is preferred in which the aim is to achieve seizure control with minimal effect on the functional integrity of tissues or fibre tracts. Cognition is important for the functions of everyday life and this should be kept in mind, irrespective of which kind of surgery is preferred.