Electroclinical characteristics, genetic findings, and complex epilepsy surgery outcomes in children with low‐grade epilepsy‐associated tumors: A comprehensive view

OBJECTIVE: To evaluate outcomes in relation to epilepsy characteristics and genetic findings in pediatric patients with isolated low-grade epilepsy-associated tumors (LEAT) and LEAT plus focal cortical dysplasia type IIIb (FCD IIIb) who underwent epilepsy surgery. METHODS: Patients younger than 19 years at the time of surgery, with isolated LEAT or LEAT plus FCD IIIb, and a minimum follow-up of 2 years were included. Clinical, neuroimaging, EEG, neuropsychological, surgical, histopathological, and molecular-genetic data were analyzed. Outcomes and potential predictors were assessed across four domains: seizures, antiseizure medication (ASM) use, cognition (Full Scale Intelligence Quotient, FS-IQ), and postoperative surgical complications. RESULTS: Seventy-one children fulfilled the inclusion criteria. Fifty-one (71.8%) had drug-resistant epilepsy. LEAT plus FCD IIIb were more frequent (43/71, 60.6%) than isolated LEAT (28/71, 39.4%). Gangliogliomas were the most common tumor type (39/71, 54.9%), followed by dysembryoplastic neuroepithelial tumors (16/71, 22.5%). Genetic testing demonstrated internal tandem duplication of the FGFR1 gene in most isolated LEAT cases (OR 11.9, 95% CI 1.32-100, p = .02), while LEAT+FCD IIIb cases were more frequently negative (OR 3.8, 95% CI 1.3-10.9, p = .02). After a median 5.7-year follow-up, 64 patients (90.1%) were seizure-free, and 55 (77.5%) discontinued ASM. Earlier seizure onset, longer epilepsy duration, and a higher number of ASM correlated with lower pre- and postoperative FS-IQ. A postoperative FS-IQ gain of >15 points occurred in four patients (7.7%). Two patients (2.8%) had unexpected permanent deficits, and 10 (14.1%) had minor temporary deficits. SIGNIFICANCE: Epilepsy surgery leads to high rates of freedom from seizures and ASM in pediatric patients with LEAT and LEAT + FCD IIIb. Early surgical intervention can be associated with higher pre- and postoperative FS-IQ. Molecular-genetic findings suggest distinct neoplastic and dysplastic entities of LEAT and LEAT plus FCD IIIb.