Novel Use of Stimulating Fence-Post Technique for Functional Mapping of Subcortical White Matter During Tumor Resection: A Technical Case Series

Abstract

Background Maximal safe resection remains a key principle in infiltrating glioma management. Stimulation mapping is a key adjunct for minimizing functional morbidity while “fence-post” procedures use catheters or dye to mark the tumor border at the start of the procedure prior to brain shift. Objective To report a novel technique using stereotactically placed electrodes to guide tumor resection near critical descending subcortical fibers. Methods Navigated electrodes were placed prior to tumor resection along the deep margin bordering presumed eloquent tracts. Stimulation was administered through these depth electrodes for subcortical motor and language mapping. Results Twelve patients were included in this preliminary technical report. Seven patients (7/12, 58%) were in asleep cases, while the other 5 cases (5/12, 42%) were performed awake. Mapping of motor fibers was performed in 8 cases, and language mapping was done in 1 case. In 3 cases, both motor and language mapping were performed using the same depth electrode spanning corticospinal tract and the arcuate fasciculus. Conclusion Stereotactic depth electrode placement coupled with stimulation mapping of white matter tracts can be used concomitantly to demarcate the border between deep tumor margins and eloquent brain, thus helping to maximize extent of resection while minimizing functional morbidity.

Applied Fence-Post Techniques Using Deep Electrodes Instead of Catheters for Resection of Glioma Complicated with Frequent Epileptic Seizures: A Case Report

“…Catheter tubes are generally used for fence-posts, but we used deep electrodes in the present case. Only one previous study used electrodes as fence-posts instead of catheters, but electrodes were used for functional mapping during surgery in this study [ 18 ]. To the best of our knowledge, this is the only report that deep electrodes were used as fence-posts for detecting the most irritative zone during surgery.…”

The Role of Extra-Operative Cortical Stimulation and Mapping in the Surgical Management of Intracranial Gliomas

“…We use preoperative DTI for identifying the tracts at risk each time, and then depth electrodes may be inserted along their pathway for stimulating and mapping in detail these tracts. However, it is beyond any doubt that intraoperative stimulation is superior to extra-operative stimulation and mapping through multiple depth electrodes or stereo-EEG [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ].…”

“…We also employed preoperative DTI in our patients (as we routinely do ), mostly for guiding us in the gross location of the tracts at jeopardy each time. This may facilitate the whole stimulation process and diminish the necessary time for stimulation and mapping; at the same time the accuracy of the DTI can be assessed intraoperatively by the employed stimulation [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ]. An adequate-size craniotomy for implanting all the electrodes under direct vision to avoid any surface venous injuries is essential.…”

Hybrid Fluoroscopic and Neurophysiological Targeting of Responsive Neurostimulation of the Rolandic Cortex

“…olandic onset epilepsy provides significant challenges for surgical treatment, given the associated morbidity with surgical resection in this eloquent region despite advances in intra-and extraoperative mapping techniques. [1][2][3][4][5] Resection of epileptic foci within the Rolandic cortices is associated with permanent neurological deficits in nearly 30% of patients. 6 Responsive neurostimulation (RNS) has been increasingly utilized to treat patients with seizures originating from eloquent regions, including seizures from the Rolandic cortex.…”

“…11,12 However, successful motor mapping and RNS via depth electrodes has been reported when surgical exposure of this eloquent area was deemed unfavorable. 5,13 Furthermore, patients with clinical seizure semiology suggesting seizure onset from the mesial Rolandic cortex (ie, early leg involvement) often undergo placement of interhemispheric strip electrodes during intracranial seizure monitoring. 14 However, the placement of interhemispheric leads has been associated with venous injury, brain contusion, and transient lower extremity weakness.…”