Cerebral motor cortical mapping: Awake procedure is preferable to general anaesthesia

Abstract

Objective: To investigate the outcome of surgical resection of cerebral lesions near or at the motor cortex under general anaesthesia or in the awake condition. Methods: Patients undergoing motor cortical mapping for tumour surgery were recruited. Surgery was carried out according to the cortical mapping protocol of the centre. Tumour location, stimulation threshold, extent of resection and postoperative complications, including neurological deficits and seizure, were recorded. Results were categorized in the awake group and in the general anaesthesia (GA) group for analysis. Results: From February 2003 to July 2006, 28 patients suffering from brain tumour (24 glioma, two metastasis and two cavernoma) were indicated for motor cortical mapping to facilitate safe tumour removal.Eight patients were in the GA group. Five tumours were subcortical lesions, whereas three were cortical lesions. There were 20 patients in the awake group. Three tumours were subcortical, whereas 17 were cortical lesions. The mean stimulation threshold was 10.75 mA (5-16 mA) in the GA group and 7.7 mA (4-12 mA) in the awake group. There were four early postoperative seizures, two transient (3-month) deficits and four permanent deficits in the GA group. One early postoperative seizure, five transient deficits and no permanent deficits were recorded in the awake group. All the permanent deficits were associated with subcortical tumours and were in the GA group. Seventy five percent of the patients achieved radiological total removal and an average extent of resection of 94.15% was achieved in the awake group. Only 37.5% of patients achieved radiological total removal and the average of extent of resection was 64.1% in the GA group. Conclusions: General anaesthesia was associated with high postoperative permanent deficit despite the effort of motor cortical mapping. Higher rate of early postoperative seizure was also found in the GA group. Awake motor cortical mapping was safer and was associated with fewer complications. We suggest that awake motor cortical mapping is preferable to the general anaesthetic technique. © 2010 The Authors. Journal compilation © 2010 College of Surgeons of Hong Kong.