Corticospinal descending direct wave elicited by subcortical stimulation

Area of Science:

• Neurosurgery
• Neurophysiology
• Brain Mapping

Background:

• Corticospinal tract (CT) mapping is crucial for tumor resection near the primary motor area (M1).
• Descending direct waves (D-waves) are established for M1 mapping and CT functional integrity monitoring.

Purpose of the Study:

• To investigate the feasibility of recording D-waves following subcortical stimulation.
• To assess the utility of subcortical D-wave recordings for intraoperative guidance.

Main Methods:

• Examined 14 patients with brain tumors near M1/CT and no pre-operative motor deficits.
• Performed electrical stimulation of subcortical white matter (monopolar/bipolar).
• Recorded descending waves (D-waves) from the spinal epidural space using a catheter electrode.

Main Results:

• Subcortical D-waves were more clearly recorded with monopolar than bipolar stimulation.
• Subcortical D-wave characteristics (waveform, velocity, latency) matched M1-stimulated D-waves.
• D-wave amplitude varied with the distance from stimulation points to the CT.

Conclusions:

• Subcortical D-wave recordings are feasible and provide information similar to M1-stimulated D-waves.
• Subcortical D-wave amplitude changes may offer valuable insights for preventing postoperative motor deficits.
• Further research is needed to correlate subcortical stimulation distance to CT with D-wave amplitude.