Artifactual signal detection using intraoperative electrocorticographic devices during functional brain mapping of...

To compare the signal detection performance of a circular grid versus a strip electrode during intraoperative electrocorticography (iECoG) for Functional Brain Mapping (FBM).

We performed a single center retrospective evaluation of signal detection by recording intraoperative ECoG comparing two intraoperative recording devices and techniques during awake craniotomy for FBM. A circular grid and linear strip evaluated stimulation artifact, afterdischarges (ADs), and epileptiform activity.

142 patients underwent awake craniotomy, and 26 (18.3 %) had reoperations with repeat iECoG performed during their subsequent procedure. A total of 71 patients underwent iECoG using circular grids and 71 with linear strip electrodes. Max and min Signal amplitudes were higher with the circular grid (p < 0.01). The minimum (2.3 vs. 2.8 mA) and maximum (4.9 vs. 6.3 mA) currents required to evoke visible stimulation artifact were lower with the circular grid (p < 0.01), suggesting increased sensitivity to stimulation-related signals. Physiological signals represented by ADs were detected in 59.2 % of circular-grid patients vs 40.8 % of strip-electrode patients (Fisher's exact p = 0.044). When adjusting for stimulation trials in a Negative Binomial model with an offset, AD rates per stimulation were 2.5 × higher with circular grids (rate ratio 2.51; 95 % CI 1.61-3.91; p < 0.0001). Total stimulation counts were 2,786 (circular) and 2,209 (strip). Notably, the circular grid also involved more electrodes (5.06 vs. 0.95,p < 0.001).

High-density circular grids enhance intraoperative detection of artifacts and ADs with lower stimulus currents.

The high-density circular grid offered more interpretable contacts and higher sensitivity.