Seizure outcome determinants in children after surgery for single unilateral lesions on magnetic resonance imaging: Role of preoperative ictal and interictal electroencephalography

Objective To determine whether an ictal electroencephalographic (EEG) recording as part of presurgical evaluation of children with a demarcated single unilateral magnetic resonance imaging (MRI) lesion is indispensable for surgical decision‐making, we investigated the relationship of interictal/ictal EEG and seizure semiology with seizure‐free outcome. Methods Data were obtained retrospectively from consecutive patients (≤18 years old) undergoing epilepsy surgery with a single unilateral MRI lesion at our institution over a 6‐year period. Video‐telemetry EEG (VT‐EEG) was classified as concordant or nonconcordant/noninformative in relation to the MRI lesion location. The odds of seizure‐free outcome associated with nonconcordant versus concordant for semiology, interictal EEG, and ictal EEG were compared separately. Multivariate logistic regression was conducted to correct for confounding variables. Results After a median follow‐up of 26 months (interquartile range = 17–37.5), 73 (69%) of 117 children enrolled were seizure‐free. Histopathological diagnoses included low‐grade epilepsy‐associated tumors, n = 46 (39%); focal cortical dysplasia (FCD), n = 33 (28%); mesial temporal sclerosis (MTS), n = 23 (20%); polymicrogyria, n = 3 (3%); and nondiagnostic findings/gliosis, n = 12 (10%). The odds of seizure freedom were lower with a nonconcordant interictal EEG (odds ratio [OR] = .227, 95% confidence interval [CI] = .079–.646, p = .006) and nonconcordant ictal EEG (OR = .359, 95% CI = .15–.878, p = .035). In the multivariate logistic regression model, factors predicting lower odds for seizure‐free outcome were developmental delay/intellectual disability and higher number of antiseizure medications tried, with a nonsignificant trend for “nonconcordant interictal EEG.” In the combined subgroup of patients with FCD and tumors (n = 79), there was no significant relationship of VT‐EEG factors and seizure outcomes, whereas in children with MTS and acquired lesions (n = 25), a nonconcordant EEG was associated with poorer seizure outcomes (p = .003). Significance An ictal EEG may not be mandatory for presurgical evaluation, particularly when a well‐defined single unilateral MRI lesion has been identified and the interictal EEG is concordant.