Neural Noise

Artifactual signal detection with intraoperative ECoG during functional brain mapping

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  • Intraoperative electrocorticographic (ECoG) devices are used during functional brain mapping of brain tumors.1
  • Artifactual signal detection methods improve reliability of ECoG-based brain mapping, which is central to neural interface and clinical electrophysiology.1 1

Weekly enrichment (2026-07-20)

  • The study (Mayo Clinic) is a single-center retrospective comparison of a customized circular grid versus a linear strip electrode for intraoperative electrocorticography (iECoG) during functional brain mapping in awake craniotomy; 142 patients (83 female, mean age 50.8 years) were included, with 26 (18.3%) undergoing reoperation with repeat iECoG, and 71 recorded with circular grids versus 71 with linear strips.2
  • Direct electrical stimulation for functional mapping was performed in 109 patients (76.8%), and both maximum and minimum recorded signal amplitudes were higher with the circular grid than the strip electrode (p < 0.01).2
  • The minimum (2.3 vs. 2.8 mA) and maximum (4.9 vs. 6.3 mA) currents needed to evoke a visible stimulation artifact were lower with the circular grid (p < 0.01), indicating greater sensitivity to stimulation-related signals.2
  • Afterdischarges (a physiological signal) were detected in 59.2% of circular-grid patients versus 40.8% of strip-electrode patients (Fisher’s exact p = 0.044); in a Negative Binomial model with an offset for stimulation trials, afterdischarge rate per stimulation was 2.5× higher with circular grids (rate ratio 2.51; 95% CI 1.61–3.91; p < 0.0001).2
  • Circular grids captured afterdischarges across more electrodes per event (5.06 vs. 0.95, p < 0.001); total stimulation counts were 2,786 (circular) versus 2,209 (strip); the work appeared in Clinical Neurophysiology (Volume 183, article 2111489; © 2025 International Federation of Clinical Neurophysiology).2
  • Context: an independent awake-craniotomy series comparing three electrode designs (194 patients; 264 electrode uses—113 circular grid, 96 strip, 55 high-density grid) found circular and HD grids detected epileptiform activity better than strips and recorded afterdischarges at a lower median stimulation intensity (3 mA vs. 5 mA, p < 0.001).3
  • Context: in that series the high-density grid was used during direct electrical stimulation far less often (15%) than the circular grid (80%) or strip electrodes (69%, p < 0.001), underscoring that both contact count and array geometry shape ECoG mapping quality.3
  • Background: electrocautery generates large-amplitude, high-frequency discharges that transiently saturate EEG/EMG amplifiers, and 50–60 Hz cortical stimulation produces a characteristic stimulation artifact in the ECoG—both nonphysiological signals that intraoperative monitoring must distinguish from true afterdischarges and seizures.4

Footnotes

  1. https://www.sciencedirect.com/science/article/pii/S1388245725013410?dgcid=rss_sd_all ↩ ↩2 ↩3

  2. https://mayoclinic.elsevierpure.com/en/publications/artifactual-signal-detection-using-intraoperative-electrocorticog/ ↩ ↩2 ↩3 ↩4 ↩5

  3. https://doi.org/10.3171/2025.7.jns251224 ↩ ↩2

  4. https://neupsykey.com/artifacts-in-neurophysiologic-intraoperative-monitoring/ ↩

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