Non-invasive Electrical Source Imaging for Localizing Epileptiform Discharges in Children with Focal Epilepsy Based on Developing Country’s Limitations

Abstract

Background: Preliminary studies have shown that electrical source imaging (ESI) has numerous advantages for the pre-surgical evaluation of epileptic patients. However, the role of ESI for children with non-lesional drug resistance in focal epilepsy has been poorly characterized. Objectives: This study aimed to investigate this issue according to interictal epileptiform discharges (IEDs) and constraints in developing countries. Methods: The present study used long-term video electroencephalography (EEG) monitoring (LTM) data that were recorded using the standard 19 scalp electrodes (10 - 20 system) and 3 tesla T1 image data. Accordingly, first, IEDs were clustered and then assessed by an epileptologist. Afterward, some operations were conducted that included EEG inverse problem solving with three known methods, namely brain electrical source analysis (BESA) with the individual head model, cortical classical LORETA analysis recursively analysis (CLARA) with the individual head model, and BESA with the age template head model. Seven children were processed in this project. Results: In most cases (n = 5, 71%), the seizure onset zone (SOZ) was the same in the LTM report and the present proposed methodology. Moreover, this study succeeded in localizing the region of the predicted SOZ. Conclusions: According to limitations in a developing country, for the configuration of multi-modal studies (e.g., 3T magnetic resonance imaging, LTM, and ESI) with a specific and valuable protocol, this investigation defined a pilot study with a 7 data sample for the first step. These findings, based on the small sample size, suggest that ESI based on combining ensemble methods improves information for children with focal drug-resistant epilepsy. It is hoped that future studies with large sample sizes show the role of ESI in developing countries more than before.