Seizure Outcome After Surgery for MRI-Diagnosed Focal Cortical Dysplasia

Abstract

Background and ObjectivesFocal cortical dysplasia (FCD) has been associated with poorer postsurgical seizure outcomes compared to other pathologies. FCD surgical series have been assembled on the basis of a histologic diagnosis, including patients with abnormal and normal preoperative MRI. However, in clinical workflow, patient selection for surgery is based on preoperative findings, including MRI. We performed a systematic review and meta-analysis of the literature to determine the rate and predictors of favorable seizure outcome after surgery for MRI-detected FCD.MethodsWe devised our study protocol in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered the protocol with PROSPERO. We searched MEDLINE, EMBASE, and Web of Science for studies of patients followed up for ≥12 months after resective surgery for drug-resistant epilepsy with MRI-detected FCD. Random-effects meta-analysis was used to calculate the proportion of patients attaining a favorable outcome, defined as Engel class I, International League Against Epilepsy class 1 to 2, or seizure-free status. Meta-regression was performed to investigate sources of heterogeneity.ResultsOur search identified 3,745 references. Of these, 35 studies (total of 1,353 patients) were included. Most studies (89%) followed up patients for ≥24 months after surgery. The overall postsurgical favorable outcome rate was 70% (95% confidence interval [CI] 64–75). There was high interstudy heterogeneity. Favorable outcome was associated with complete resection of the FCD lesion (risk ratio [RR] 2.42 [95% confidence interval (CI) 1.55–3.76], p < 0.001) and location of the FCD lesion in the temporal lobe (RR 1.38 [95% CI 1.07–1.79], p = 0.013) but not lesion extent, intracranial EEG use, or FCD histologic type. The number of FCD histologic types included in the same study accounted for 7.6% of the observed heterogeneity.DiscussionSeventy percent of patients with drug-resistant epilepsy and MRI features of FCD attain a favorable seizure outcome after resective surgery. Our findings can be incorporated into routine preoperative counseling and reinforce the importance of completely resecting the MRI-detected FCD when safe and feasible.