Intraoperative functional mapping and monitoring during glioma surgery

Abstract

Glioma surgery represents a significant advance with respect to improving resection rates using new surgical techniques, including intraoperative functional mapping, monitoring, and imaging. Functional mapping under awake craniotomy can be used to detect individual eloquent tissues of speech and/or motor functions in order to prevent unexpected deficits and promote extensive resection. In addition, monitoring the patient's neurological findings during resection is also very useful for maximizing the removal rate and minimizing deficits by alarming that the touched area is close to eloquent regions and fibers. Assessing several types of evoked potentials, including motor evoked potentials (MEPs), sensory evoked potentials (SEPs) and visual evoked potentials (VEPs), is also helpful for performing surgical monitoring in patients under general anesthesia (GA). We herein review the utility of intraoperative mapping and monitoring the assessment of neurological findings, with a particular focus on speech and the motor function, in patients undergoing glioma surgery.

Fig. 1

The screen of the dedicated intraoperative examination monitor for awake craniotomy (IEMAS). Upper left display: The patient’s face. Lower left display: The anatomical data obtained from the real-time updated neuronavigation system, which can be used to localize the exact position of the stimulator. Upper right display: Four different sets of data for the test object, bispectral index monitor, heart beat monitor, and general view of the operating theater. Lower right display: The view of the surgical field through the operative microscope.

Fig. 2

Intraoperative CCEP monitoring. Changes in CCEP were recognized following stimulation of the frontal language area and recordings of the temporal language area. CCEP: cortico-cortical evoked potential.

Fig. 3

A, B: Magnetic resonance (MR) images obtained before the second surgery demonstrating regrowth of the residual tumor just posterior to the prior resection cavity located in the frontal operculum. The tumor is hyperintense on axial T₂-weighted image (T₂WI) (A) and sagittal fluid attenuated inversion recovery (FLAIR) image (B). C, D: MR images obtained after the second surgery showing that the tumor had been subtotally removed on T₂WI (C) and FLAIR (D).