Microstereometrically guided cortical stimulation for the intraoperative identification of the central motor strip

A rangable stimulation tool based on the sonar microstereometric system has been developed for the intraoperative identification of the central motor strip. The elicited motor evoked potentials (MEPs) were recorded with surface electrodes and displayed together with the corresponding stereometric coordinates of the stimulation site. MEP data were overlaid in 'real time' on preoperatively scanned CT images on a computer screen. The system has been used during open microsurgical procedures in 6 patients with small tumors near the central motor strip or related 'eloquent' areas. Three operations have been performed under local anesthesia, 3 under general anesthesia. It was possible to operate on tumors located closely to functionalal relevant areas of the brain not only stereotactically, but also with function guidance.