Electrophysiological Mapping and Monitoring during an Awake Craniotomy for Low-Grade Glioma: Case Report

A Cost-Effective, Adjustable, Dynamic Subcortical Stimulation Device - Technical Note

Brain mapping and neuromonitoring remain the gold standard for identifying and preserving functional neuroanatomic regions during safe, maximal brain tumor resection. Subcortical stimulation (SCS) can identify white matter tracts and approximate their distance from the leading edge of an advancing resection cavity. Dynamic (continuous) devices permitting simultaneous suction and stimulation have recently emerged as time-efficient alternatives to traditional static (discontinuous) techniques. However, the high cost, fixed cap size, and fixed tube diameter of commercially available suction devices preclude universal adoption. Our objective is to modify available suction devices into monopolar probes for subcortical stimulation mapping. We describe our technique using a novel, cost-effective, dynamic SCS technique as part of our established neuromonitoring protocol. We electrified and insulated a conventional variable suction device using an alligator clip and red rubber catheter, respectively. We adjusted the catheter's length to expose metal on both sides, effectively converting the suction device into a monopolar stimulation probe capable of cortical and subcortical monopolar stimulation that does not differ from commercially available discontinuous or continuous devices. We fashioned a dynamic SCS suction probe using inexpensive materials compatible with all suction styles and sizes. Qualitative and quantitative analysis in future prospective case series is needed to assess efficacy and utility.

Brain Mapping-Aided SupraTotal Resection (SpTR) of Brain Tumors: The Role of Brain Connectivity

Brain gliomas require a deep knowledge of their effects on brain connectivity. Understanding the complex relationship between tumor and functional brain is the preliminary and fundamental step for the subsequent surgery. The extent of resection (EOR) is an independent variable of surgical effectiveness and it correlates with the overall survival. Until now, great efforts have been made to achieve gross total resection (GTR) as the standard of care of brain tumor patients. However, high and low-grade gliomas have an infiltrative behavior and peritumoral white matter is often infiltrated by tumoral cells. According to these evidences, many efforts have been made to push the boundary of the resection beyond the contrast-enhanced lesion core on T1w MRI, in the so called supratotal resection (SpTR). SpTR is aimed to maximize the extent of resection and thus the overall survival. SpTR of primary brain tumors is a feasible technique and its safety is improved by intraoperative neuromonitoring and advanced neuroimaging. Only transient cognitive impairments have been reported in SpTR patients compared to GTR patients. Moreover, SpTR is related to a longer overall and progression-free survival along with preserving neuro-cognitive functions and quality of life.