Impact of intraoperative MRI on outcomes in epilepsy surgery: preliminary experience of two years

Abstract

Purpose: To determine the impact of intraoperative magnetic resonance imaging (iMRI) in epilepsy surgeries on the extent of surgical resection and seizure outcome along with its feasibility and limitations.

Methods: Patients with pharmacoresistant epilepsy (PRE), who underwent surgeries in operating theater equipped with high-field 1.5-Tesla MRI, were evaluated for extent of resection, operative time, scanning time, pathologies, resultant extra resection, and seizure outcomes.

Results: Thirty-nine patients with mean age of 18 (range: 3-65) years with PRE underwent surgical intervention. Mean duration of epilepsy was 10.2 years. Surgical interventions included tumor resection (31%), resection of focal cortical dysplasia (28%), mesial temporal lobe surgeries (18%), and disconnection surgeries (23%). iMRI alone, apart from navigation and electrophysiology, improved resection rates in 13% (5 out of 39) of these patients. In lesional group, iMRI modified operative strategy resulting in increased resections in 21% (5/23) patients. Complete resection was observed in 87% of patients. iMRI scanning time constituted 25% (mean: 72 ± 21 min) of time spent under anesthesia by the patient. Major and minor complications were observed in 2.5% and 7.5% of patients, respectively. The mean follow-up was 14 months. Favorable postoperative seizure control (Engel Classes I and II) was achieved in 85% and complete seizure freedom was achieved in 77% of patients (Engel Class IA) at 1-year follow-up.

Conclusions: iMRI increases the extent of resection mainly in lesional epilepsy surgeries translating into good seizure outcomes but not found to be much beneficial in prototype mesial temporal sclerosis surgeries and disconnection surgeries.

Keywords: epilepsy surgery; intraoperative MRI; lesional epilepsy; seizure outcome.