Abstracts

Rationale: Previous studies on medication discontinuation after successful surgery in children have been done but are not specific to focal cortical dysplasia (FCD). 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 2014 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: Fifty nine (59 patients) FCD resections were identified. Twenty five patients had Engel 1 outcome and medications were tapered. Nineteen patients’ medications were not tapered due to seizures (Engel 2 (5); 3 (12); 4 (2)), 2 noncompliant and 3 seizure free post-op but AEDs not tapered. No follow up data in (9) seen by outside neurologists and (1) lost to follow up. For the 25 patients with Engel 1 outcome, seizure onset was 1 week to 10 years. Twenty five had focal epilepsy and 3 also had facilitated spasms. Twenty one had FCD confirmed on initial MRI and 4 did not (one had FDG PET that lead to FCD identification). Five out of 25 were seizure free and AEDs were discontinued. Out of these 5, 4 had tapering of AED < 6 months post-op. In 3, age of seizure onset was > 4 to 10 years, 4 had no post-op MRI residual dysplasia and all had no spike waves on post-op EEGs. 20 % had an abnormal exam. Nine out of 25 were tapering AEDS and seizure free. In 4, tapering was started < 6 months post-op, 3 at 6 mos- 1 year and 2 > 1-2 years. Eight out of 25 had seizure relapse during AED withdrawal or discontinuation. Four 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 7 months to 6 years after starting taper. In 7 out of 8 (87%), age of seizure onset was < 2.5 years. Three had spasms and 2 had contralateral EEG findings. Three had residual dysplasia on post-op MRI and 7 out of 8 were extratemporal. In 6, post-op EEGs were abnormal with spike waves (1 no post-op EEG). 63 % had an abnormal exam. Three out of 25 were seizure free and tapering AEDs after second resection only. In all 3 tapering was started < 6 months. Two of the 3 had no residual dysplasia on post-op MRI. Post-op EEG showed no spike waves (1 no post-op EEG).Conclusions: Children can successfully discontinue AEDs after FCD resection. The optimal timing of AED withdrawal is not determined. Our data suggests seizure onset at older age, complete resection, normal post-op EEGs, and normal exams were positive predictive factors. In our limited study, AEDs tapered < 6 months post-op had good outcome in children with positive predictive factors. Pathology, number of AEDs pre-op and location did not affect relapse rate. Factors that may increase relapse are age of onset < 2.5 years, abnormal exams, contralateral EEG findings, spasms, residual dysplasia and abnormal post-op EEGs suggesting a conservative and slower taper.