Yield of video electro encephalography for phase 1 pre-surgical evaluation of drug resistant epilepsy in 1200 adults: retrospective study from a tertiary center situated in a lower-middle-income country.

Abstract

Video Electroencephalography (VEEG) is crucial for presurgical evaluation of Drug Refractory Epilepsy (DRE). The yield of VEEG in large volume centers, particularly those situated in Low-and Middle-Income countries (LMIC) is not well studied. We studied 1200 adults with drug resistant focal epilepsy whose seizures were recorded during VEEG in the epilepsy monitoring unit. VEEG review and analysis was done independently by trained epileptologists. Video EEG and MRI data were examined for concordance in order to generate a hypothesis for the presumed epileptogenic zone. Analysis of seizure semiology provided information on the symptomatogenic zone in most cases except for 33 (2.75%) patients. A total of 1050 (87.5%) patients showed interictal epileptiform discharges (IEDs) with most (58.3%) showing unilateral IEDs. Most patients (n = 1162, 96.83%) showed ictal EEG discharges of which 951(81.8%) had unilateral ictal onset. Abnormal MRI was seen in 978 (81.5%) patients. Concordance of electroclinical data obtained by analysis of VEEG with MRI abnormality could be established in most patients (63%). Concordance was higher for patients with ictal onset from temporal regions (83.71%) as compared to posterior cortex (55.4%) and frontal regions (43.5%.) CONCLUSION: This study highlights the high yield of VEEG in phase 1 presurgical evaluation in DRE. Systematic evaluation of data from VEEG provided lateralizing and localizing information in most cases. Concordance between VEEG and MRI findings was noted in most patients. These findings support steps to increase referral for pre-surgical evaluation in DRE.