Role of intraoperative MRI in epilepsy surgeries: Preliminary experience for two years

Background: Epilepsy surgery often involves resection substrates that are subtle and often require special MRI sequences to detect them. Guidance at the time of surgery is often by visual cues, neuronavigation and EEG parameters. Intra-operative MRI (iMRI) may provide better guidance especially in providing information about total excision that has a clear impact on outcome.

Objective: To determine the usefulness of iMRI in epilepsy surgeries with regards to extent of surgical resection and seizure outcome along.

Study design: Longitudinal, observational.

Methods: Patients undergoing epilepsy surgeries in intra-operative MRI OT were primarily evaluated for extent of resection, operative time, pathologies, resultant extra resection, and seizure outcome along with complications.

Results: Thirty-nine patients with mean age of 18 years (range 3–65 years) with PRE underwent surgical intervention. Mean duration of seizures was 10.2 years. Surgical interventions included tumor resection (23%), resection of focal cortical dysplasia (28%), medial temporal lobe surgeries (18%) and disconnection surgeries (31%). In 13% (5 out of 39) of these patients, iMRI was decisive and resulted in increased resection of lesions despite extensive use of electrocorticography and navigation in all cases. This is only observed for lesional pathologies where it made 36.6% change in surgeon's intra-operative decision. Complete resection was observed in (89%) of patients. It is at the cost of 24% increase in operative time without any clinical complications of prolonged anesthesia and surgeries. Major and minor complications were observed in 2.5% and 10% 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 in 77% patients.

Conclusions: iMRI increases the extent of resection mainly in extratemporal lesional epilepsy surgeries translating in good seizure outcomes and not found to be much beneficial in medial temporal sclerosis surgeries and disconnection surgeries. Increase in operative times does not found to lead any clinical significant complications.