Intraoperative electrophysiological principles in neurooncological practice

Abstract

Intraoperative neurophysiological monitoring (IOMN) is an important adjunct in modern day neurosurgical practice. There has been a paradigm shift from functional preservation to maximal safe or total excision of a tumor along with functional preservation, aiming for a better quality of life to the patients. In neurosurgery, like in any other specialty, we have two extremes of tumors, benign and malignant. In malignant tumors, the extent of resection, along with molecular genetics of the tumor, play an important role in the survival of patients. Thus, one should target for complete resection, whenever feasible, in these types of tumors. In benign tumors, such as World Health Organisation (WHO) grade 2 gliomas, a good chance of long-term survival exists. IOMN is a valuable adjunct in neurosurgical practice that guides the surgeon and warns him/her of the important neurological structures in the vicinity, during surgery. The IOMN procedures, however, have their own limitations that everyone should be aware of. The technique has been used along with other adjuncts like a preoperative MRI (including the functional magnetic resonance imaging [MRI], diffusion tensor imaging of long tracts and perfusion studies), neuronavigation and intraoperative imaging to maximize the chances of a better outcome in the form of onco-functional balance. In this review, an overview of IONM has been discussed.