Towards a sensitive awake craniotomy: assessment of electrical mapping thresholds

Background. Awake surgery is currently a safe and reliable alternative for identifying and preserving functional areas. However, this protocol has evolved over time to minimize the occurrence of electrical stimulation-induced seizures and postoperative deficits. Objective. The aim of this study is to highlight both internal and external factors influencing the language and sensorimotor thresholds of electrical stimulation mapping (ESM) during gliomas awake surgery. Material and methods. From October 2016 to April 2022, we performed a retrospective study on 74 patients underwent awake craniotomy of gliomas in two series based on ESM: group 1 and group 2. Preoperatively and three months after surgery, general performance and neurological deficits were assessed according to the type, location, and side of the tumor in correlation with ASA, BMI, Mallampati and KPS indexes. Results. The outcome shows that the median patient age was 49 years old in a range of [13-70], functional mapping was performed in language areas for 96% of patients and motor functions for 54%. In addition, 55.5% of the patients had HGG, 40.5% had LGG, and 4% had AVMs. Most lesions were in the temporal area (40.5%), followed by the frontal area (31%), 24.5% for insular area, 4% for the parietal area, and 85% of patients had left-sided lesions. The overall rate of intraoperative complications fell from 16.2% in group 2 to 1.35% in group 1. Conclusions. Under the ESM threshold of group 1, a high-quality of awake surgery can be used with optimally low complications and failure rates regardless of BMI, ASA rating, Mallampati and KPS scores or smoking status.