Combined Use of DES, EMG and MEP Monitoring, ECoG and EEG for Surgical Resection of Gliomas

Surgery for gliomas aims to remove as much of the tumour mass as possible while at the same time preserving the patient’s functional integrity. This policy particularly applies to resection of gliomas located close to or within the so-called ‘eloquent’ areas, i.e. areas that are involved in motor, language or visuospatial functions. In these cases, extended resection and maximal functional integrity can be achieved by using a cohort of procedures that make up the so-called brain-mapping techniques. These include neuropsychological evaluation, imaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging–fibre tracking (DTI-FT) – generally loaded into the neuronavigation system so as to be available peri-operatively – and a series of neurophysiological techniques available at the time of surgery such as cortical and subcortical direct electrical stimulation (DES), motor-evoked potentials (MEPs), multichannel electromyogram (EMG), electroencephalogram (EEG) and electrocorticogram (ECoG) recordings. In this article we will focus on these neurophysiological adjuncts by describing the protocol in use at our institution for resection of gliomas, and by discussing the rationale and indications for and the results of our experience.