Electroclinical Characteristics, Genetic Findings And Complex Epilepsy Surgery Outcomes In Children With Low-Grade Epilepsy-Associated Tumors - A Comprehensive View

ObjectiveTo analyze postsurgical outcomes in relation to epilepsy characteristics and genetic etiology 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. MethodsPatients younger than 19 years at the time of epilepsy surgery, with isolated LEAT or LEAT plus FCD IIIb and a minimum follow-up of 2 years were included. Clinical data, neuroimaging, EEG, neuropsychological findings, surgical variables, histopathological and molecular-genetic findings were evaluated. Surgical outcomes were assessed in four domains: seizures, antiseizure medication (ASM) use, cognitive performance changes and complications, including predictor analysis. ResultsSeventy-three children fulfilled the inclusion criteria, with 53 (72.6%) having drug-resistant epilepsy. LEAT plus FCD IIIb were more frequent than isolated LEAT (44/73, 60.3% vs. 29/73, 39.7%) and gangliogliomas were the most common tumor type (43/73, 58.9%), followed by dysembryoplastic neuroepithelial tumor (19/73, 26.0 %). Genetic testing was more frequently positive in isolated LEAT (20/28) than LEAT plus FCD IIIb (18/43, p = 0.02). At the end of follow-up (median 5.7 years), 66 patients (90.4%) were seizure-free, and 57 (78.1%) had discontinued ASM. Younger age at seizure onset, longer epilepsy duration, and a higher number of ASM were correlated to lower pre- and postoperative IQ. An IQ gain of > 10 pts. postoperatively was present in 8 patients (15.1%). Two patients (2.7%) had an unexpected permanent deficit, while 10 (13.7%) had minor temporary deficit. No additional predictive outcome factors were identified. SignificanceEpilepsy surgery yields high chances of freedom from seizures and ASM discontinuation. Early surgical intervention in terms of shorter duration of epilepsy and fewer used ASM can be associated to a higher pre- and postoperative IQ. Molecular-genetic differences between isolated LEAT and LEAT plus FCD IIIb suggest distinct neoplastic and dysplastic entities, respectively. Key pointsO_LIA majority of patients with LEAT achieved freedom from seizures and ASM post-surgically. C_LIO_LIChildren with younger age at seizure onset, longer duration of epilepsy and a higher number of ASM used before surgery had lower pre- and postoperative IQ. C_LIO_LIGenetic cause was detected more often in patients with isolated LEAT vs. LEAT + FCD IIIb implying their neoplastic respectively dysplastic origin. C_LI