Abstracts

Rationale: Discontinuation of medication after successful surgery in children with focal cortical dysplasia (FCD) is achievable but studies are limited on the timing. Our aim was to identify the optimal timing for discontinuation of antiepileptic drugs (AEDs) in children with seizure-free outcomes after FCD resection and determine positive predictive factors. Methods: We identified patients from 2007 to 2018 who underwent FCD resections for medically refractory epilepsy with at least one year post-op follow up. The epilepsy surgery database and medical records were queried for age of seizure onset, seizure type, MRI/EEG findings, AEDs, pathology and outcome.  Results: Ninety one (91 patients) FCD resections were identified. Thirty five patients had Engel 1 outcome and medications were tapered. Twenty eight patients' medications were not tapered due to seizures (Engel 2 (8); Engel 3 (16); Engel 4 (2) and 2 were noncompliant. Six were seizure free post-op but AEDs were not tapered due to patient preference. There was no follow up data in 15 (referred by outside neurologist) and 7 were lost to follow up. For the 35 patients with Engel 1 outcome, seizure onset was 2nd day of life to 10 years. Thirty five had focal epilepsy (5 had facilitated spasms additionally). Thirty had FCD confirmed on initial MRI and five did not (3 had FDG PET that lead to FCD identification). Eleven out of 35 were seizure free and AEDs were discontinued. Out of these 11, 7 had tapering of AED < 6 months post-op. Of these 11, age of seizure onset was > 3 to 10 years (5/11), no post-op MRI residual dysplasia (9/11), and all had no spike waves on post-op EEGs. Only 1 had an abnormal exam. Twelve out of 35 are in the process of being tapered. Of the twelve, tapering was started < 6 months (5/12), 6 months to 1 year (5/12), and > 1-2 years (2/12). All are seizure free. Six out of 35 had seizure relapse during AED withdrawal or discontinuation. Two relapsed when the AED was tapered off <6 months post-op, 3 at 6 mos to 1 year and 1 at 1-2 years. Relapse occurred 11 months to 2 years after starting taper. In 5 out 6 who relapsed (83%), age of seizure onset was < 3 years, the FCD was extratemporal and the post-op EEGs had spike waves. Two had contralateral EEG findings, 2 had residual dysplasia on post-op MRI, and 2 had an abnormal exam. Six out of 35 who had a 2nd or 3rd epilepsy surgery were seizure free and on tapering AEDs. Three of these patients had facilitated spasms and focal seizures. In five out of the 6, tapering started < 6 months after the surgery. There was no residual dysplasia on all post-op MRI. Two out of 6 had spike waves on post-op EEG, slowing (1), suppression (1), and no post-op EEG (2).  Conclusions: Children can be successfully discontinued from AEDs after FCD resection. Seizure onset > 4 years of age, complete resection, normal post-op EEGs, and normal exams were positive predictive factors. AEDs tapered even < 6 months post op, had good outcome with positive predictive factors although our numbers are limited. Pathology, number of AEDs pre-op and location did not affect relapse rate. Factors that might increase relapse rate are age of onset <3 years, abnormal exams, contralateral EEG findings, residual dysplasia and abnormal post-op EEGs and suggest a more conservative and slower taper.  Funding: No funding