Neuropsychological outcome after surgery of frontal lobe epilepsy in children with good seizure outcome

Abstract

One third of children with drug-resistant epilepsy included in surgical programmes have frontal lobe epilepsy. Frontal lobe epilepsy in itself constitutes a high risk of impacting neurocognitive and behavioral development. In this study, we characterized the long-term neuropsychological and behavioral outcomes of children with pharmacoresistant structural focal epilepsy who underwent frontal neurosurgery. The clinical variables that may influence these outcomes were also investigated. A comprehensive neuropsychological evaluation – including a behavioral questionnaire − was administered to 37 children on long-term postoperative follow-up (5.1 years ± 2.9) using the Wechsler Intelligence Scale for Children, Fluency task, Rey-Osterrieth Complex Figure, Trail Making Test, Tower of London, Wisconsin Sorting Card Test and Achenbach Child Behaviour Inventory. To assess executive functions in the youngest children, we administered the junior version of EpiTrack. The clinical characteristics were as follows (mean in years ± standard deviation): Engel I (78 % with among them 96 % without anti-seizure medication), age of onset of seizures (3.5 ± 2.9), preoperative delay (3.9 ± 2.5), neurosurgical age (7.5 ± 3.6), FCD (n = 25) versus LEAT (n = 12) aetiologies. In our series, the children had an average FSIQ (92 ± 17) with a significant difference between VCI which was higher than WMI and PSI. About a third of the children experienced weakness of the executive functions with some difficulties in phonemic verbal fluency and slowness in attentional tasks, and a long execution time in planning, as well as impaired conceptualization and organization capacities. Mild to severe alteration on the Epitrack Junior was found in the majority of the youngest patients although they had a mean FSIQ of 96. At the behavioral level, around a quarter of children reached a pathological score in the attentional, social and anxiety/depression domains. Regarding the effects of clinical variables, we demonstrated that early age at surgery, shorter disease duration and LEAT etiology, were good prognosis factors for neuropsychological outcomes. Early frontal lobe resection followed by good seizure outcome efficiently determines intellectual and neuropsychological trajectory in selected patients. Our results help to better understand the cognitive and behavioral outcomes of this pediatric population, who may benefit from cognitive follow-up and adapted intervention when weaknesses are identified.