Combining interictal and ictal low-density EEG source imaging to delineate the epileptogenic zone in young children

The aim of this study was to evaluate the feasibility of low-density (LD) interictal (IIC) and ictal (IC) electrical source imaging (ESI), and to assess their individual and combined diagnostic accuracy and predictive value in a cohort of children with drug-resistant epilepsy (DRE) who underwent resective surgery before the age of 7. Retrospective analysis was conducted on de-identified EEG and MRI data, which were (semi)-automatically processed, blinded to clinical information, to compute both IIC and IC-ESI. The concordance of ESI localizations with the resection cavity at sublobar level, and the association with surgical outcome were assessed. Thirty-two children were included. IIC- and IC-ESI showed an accuracy of 66 ​% (CI 95 ​% 47-81 ​%) and 72 ​% (CI 95 ​% 53-86 ​%) and a diagnostic odds ratio (DOR) of 3.0 (CI 95 ​% 0,66-13,69; p ​= ​0,15) and 5.0 (CI 95 ​% 0,91-27,47; p ​= ​0,06), respectively. The combined approach increased diagnostic performance, achieving an overall accuracy of 75 ​% and a DOR of 11.4 (CI 95 ​% 1.08-120,35; p ​= ​0,042). In multivariate logistic regression analysis, the combined IIC/IC ESI result emerged as the strongest predictor of postsurgical seizure freedom (OR: 222,28; p ​= ​0,0262; AUC: 0.87). These findings demonstrate that combined (semi)-automated LD-IIC and IC-ESI is feasible and can accurately localize the epileptogenic zone and predict postsurgical seizure freedom in children under 7 years of age. ESI may support earlier surgical referral, reduce the time from epilepsy onset to surgery, and ultimately improve long-term outcomes.