Impact of Intraoperative Neurophysiological Monitoring on Surgery of High-Grade Gliomas

Introduction: Controversy exists on the application of intraoperative monitoring (IOM) procedures during malignant glioma surgery. Because resection rate correlates with the survival rate, it is of paramount importance to determine these values. This study evaluates the impact of IOM on the resection rates, the survival rate, the quality of life, and the functional outcome of malignant gliomas. Methods: Forty patients with a glioma were included in the study. They were divided into two groups: group 1, patients with a glioma not adjacent to motor cortical areas operated without the use of IOM, and group 2, patients with a glioma adjacent to the central region operated under IOM. The further treatment was the same in both groups. The following parameters were analyzed: tumor resection rate, survival rate, preoperative and postoperative Karnowsky Performance Score, and preoperative and postoperative motor function. Results: There were no statistically significant differences in the type of surgery performed or in the resection grade in both groups. No statistically significant difference was found in the median survival of the two groups in the Kaplan-Meier analysis with mean survival time 48.8 and 48.2 weeks. The mean Karnowsky Performance Score preoperative was 82.5 and 81.5, and 81.1 and 82.7 after 6 months, for groups 1 and 2, respectively. Conclusion: The data presented here demonstrate that tumor resection is not negatively influenced by IOM. Accordingly, gliomas that are found to be otherwise resectable should not be excluded from aggressive management simply because of their vicinity to the motor cortex. Surgery should be performed under IOM.