Seizure Outcome After Surgery for MRI-Diagnosed Focal Cortical Dysplasia: A Systematic Review and Meta-analysis.

Abstract

Focal cortical dysplasia (FCD) has been associated with poorer post-surgical seizure outcomes compared to other pathologies. FCD surgical series have been assembled on the basis of a histological diagnosis, including patients with abnormal as well as normal pre-operative MRI. However, in clinical workflow, patient selection for surgery is based on pre-operative 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. We devised our study protocol in accordance with PRISMA guidelines and registered the protocol with PROSPERO. We searched MEDLINE, EMBASE, and Web of Science for studies of patients followed 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, ILAE Classes 1-2, or "seizure-free" status. Meta-regression was performed to investigate sources of heterogeneity. Our search identified 3,745 references. Of these, 35 studies (total of 1,353 patients) were included. Most studies (89%) followed patients for ≥24 months post-surgery. The overall post-surgical favorable outcome rate was 70% (95% CI: 64-75). There was high inter-study heterogeneity. Favorable outcome was associated with complete resection of the FCD lesion [risk ratio, RR=2.42 (95% 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=0013], but not lesion extent, intracranial EEG use, or FCD histological type. The number of FCD histological types included in the same study accounted for 7.6% of the observed heterogeneity. 70% of patients with drug-resistant epilepsy and MRI features of FCD attain a favorable seizure outcome following resective surgery. Our findings can be incorporated in routine pre-operative counselling and reinforce the importance of resecting completely the MRI-detected FCD where this is safe and feasible.