Imaging techniques for presurgical evaluation of temporal lobe epilepsy

Abstract

The surgical treatment of pharmaco-resistant focal epilepsy has increased dramatically in recent years. This evolution is undoubtedly due to an improvement of electrophysiological and neuroradiological investigations to localize the epileptic focus. Temporal lobe epilepsy is the most frequent pharmacoresistent epileptic syndrome in adults and responds better to surgery than the so-called extratemporal epilepsy. Apart from the history and the clinical semiology, the investigations for temporal lobe epilepsy are based on core investigations, including electroencephalography (long-term video-EEG recordings) and MRI. Additional noninvasive imaging techniques to improve the localization of the epileptic focus include PET ictal and interictal SPECT, electric source imaging and magnetic source imaging, and simultaneous EEG and functional MRI. Advanced sequences and analysis of structural MRI data allow us to map subtle structural abnormalities as well as important white matter tracts while functional MRI of language/memory helps to identify eloquent cortical area and estimate the risk of postoperative deficits. Our aim is to review the current literature and summarize all available data on these validated imaging techniques for the assessment of focal temporal lobe epilepsy.