Preoperative Magnetoencephalography Improves Tumor Resection Safety in Awake Craniotomy: Our Initial Experience

Objectives: The purpose of presurgical brain mapping is to facilitate surgical planning, prevent or reduce morbidity, and optimize the therapeutic effects of surgery. We report our experience of combining awake craniotomy (AC) techniques with preoperative Magnetoencephalography (MEG) for tumors adjacent to eloquent cortex.

Methods: We obtained and evaluated the records of all patients who had undergone combined preoperative MEG and awake craniotomy for tumors adjacent to eloquent cortex. Patients’ Demographics, presentation, tumor characteristics, intraoperative neuromonitoring, extent of resection, and neurological outcome were assessed retrospectively.

Results: Between march 2013 and feb 2015, 11 (8 females, 3 males, average age = 40.5)awake craniotomies with preoperative MEG were performed for resection of 10 intra-axial tumors(3 grade II oligodendroma, 1 grade III oligodendroma, 3 glioblastoma multiforme, 1 grade II astrocytoma, 2 grade III astrocytoma) and 1 metastatic non small cell carcinoma. The presenting symptoms were mainly seizures and speech difficulties. The mean follow-up period was 15 months. The mean operative time was 189 minute. Gross total resection was achieved in 73% (n = 8), near total resection in 18% (n = 2), and subtotal resection in 18%(n = 2) . No subsequent surgeries for further resection performed on any of the cases. None of the patients had permanent post operative neurological deficit. One patient with glioblastoma multiforme had disease progression and died 24 months after the surgery.

Conclusions: MEG provides reliable non-invasive technique for pre-surgical mapping of eloquent brain cortex. Awake craniotomy can be safely performed combined with preoperative MEG to maximize tumor resection with an acceptable morbidity profile. Better preoperative craniotomy planning, reasonable confidence with tumor resection, shorter operative time, and satisfactory neurological outcome are the natural results of combining MEG with AC.