Intraoperative magnetic resonance imaging in epilepsy surgery: systematic review of the literature and meta-analysis

INTRODUCTION: Intraoperative magnetic resonance imaging (iopMRI) is increasingly incorporated into neurosurgery to improve outcomes. However, its usefulness in epilepsy surgery remains debated. To elucidate its current role, we conducted a systematic review of the data published to date. EVIDENCE ACQUISITION: We performed a systematic review of the available literature using the PubMed, Scopus, and Embase database. Only articles detailing the usefulness of iopMRI in quantifiable measures were included. Different aspects of iopMRI in epilepsy surgery were analyzed and two meta-analyses summarizing its impact on extent of resection and seizure outcomes performed. EVIDENCE SYNTHESIS: A total of 33 articles met the inclusion criteria, comprising a total of 1313 patients, both children and adults operated under iopMRI guidance. The mean rate of return to surgery was 29.2% in 30 articles reporting this number. Eleven publications were eligible for meta-analysis of seizure outcome in patients with refractory epilepsy, who had undergone surgery with iopMRI (N.=294) compared to controls (N.=298). Eight articles described the impact of iopMRI on the radiological extent of resection. In both regards, usage of iopMRI improved outcomes in our meta-analysis with an OR of 3.8 and 4.75, respectively. CONCLUSIONS: This work presents the first meta-analysis of the value of iopMRI in epilepsy surgery. Its use resulted in an improvement of the desired extent of resection and led to a better seizure outcome compared to conventional surgery. Understanding its benefits might help improve surgical strategies in traditional, open epilepsy surgery.