Defined as suspected invasion of the precentral gyrus or compression without identifiable sulcus between tumor and precentral gyrus and/or suspected invasion of the corticospinal tract.

Infiltration of presumed motor eloquent area based on preoperative MR images is a risk factor for both in complete resection and postoperative motor deficit.

Hence, areas of presumed motor eloquence should be tested by intraoperative neuromonitoring to optimize the oncological benefit of surgery

Resection of a motor eloquent lesion has become safer because of intraoperative neurophysiological monitoring (IOM). Stimulation of subcortical motor evoked potentials (scMEPs) is increasingly used to optimize patient safety.

A proof-of-concept analysis showed that tumors adjacent to motor eloquent areas may be safely removed down to motor thresholds MTs as low as 1–3 mA, so long as motor evoked potential (MEP) monitoring remains stable.