%0 Journal Article
%T Role of Electroencephalography in Presurgical Evaluation of Temporal Lobe Epilepsy
%A Seetharam Raghavendra
%A Javeria Nooraine
%A Seyed M. Mirsattari
%J Epilepsy Research and Treatment
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/204693
%X Surgery remains a therapeutic option for patients with medically refractory epilepsy. Comprehensive presurgical evaluation includes electroencephalography (EEG) and video EEG in identifying patients who are likely to benefit from surgery. Here, we discuss in detail the utility of EEG in presurgical evaluation of patients with temporal lobe epilepsy along with illustrative cases. 1. Introduction Temporal lobe epilepsy (TLE) is the most common form of epilepsy worldwide. Anterior temporal lobectomy (ATL) for medically refractory TLE secondary to mesial temporal sclerosis (MTS) is the most commonly performed surgical procedure in many of the comprehensive epilepsy management centres. Surgery is ideally directed towards complete seizure freedom without or with very minimal cognitive or functional deficits. Wiebe et al. in 2001 published the only randomised control study demonstrating the effectiveness of surgery in adults with medically refractory TLE [1]. Here, we would like to emphasise that the art of presurgical workup is to effectively use all the clinical, imaging, and electrophysiological information to localize the seizure onset zone (SOZ) and the epileptic network. In this paper, the electroencephalography (EEG) aspects of TLE with relevance to surgery are discussed with illustrative cases (see Table 1). Table 1: Clinical details of the illustrative cases. 2. Surface EEG Electrophysiological assessment remains the cornerstone for patients with TLE [10]. Standard EEG with 10¨C20 system provides limited coverage of the temporal regions detecting only about 58% of temporal spikes or interictal epileptiform discharges (IEDs). Additional electrodes help in increasing this yield [11, 12]. SilvermanĄ¯s electrodes (T1 and T2, placed at posterior one-third and anterior two-thirds of a line connecting the outer canthus of the eye and the tragus) are often used to record from the anterior-basal areas of the temporal lobes [13¨C16]. Mandibular notch, nasopharyngeal (NP), sphenoidal (SP), and foramen ovale (FO) electrodes also help similarly. NP recordings are cumbersome and provide little information over the well-tolerated routine anterior temporal and ear recordings especially with regard to anterior temporal IEDs [17, 18]. However, NP recordings have increased sensitivity for IEDs arising from mesiobasal temporal regions (increasing IEDs identification by 25%) [19]. FO electrodes offer a unique opportunity for simultaneous intracranial and surface EEG recording without breach of the skull. They may lateralize seizures in adults and children with mesial TLE
%U http://www.hindawi.com/journals/ert/2012/204693/