Intraoperative Mapping and Monitoring of the Pyramidal Tract Using Endoscopic Depth Electrodes.

Abstract

To evaluate motor function during neuroendoscopic resectioning of deep-seated brain tumors using endoscopically guided depth electrodes. For 12 cases of thalamic tumors, including high-grade gliomas, germinomas, and malignant lymphomas, depth electrodes were inserted using endoscopic guides between the tumor and the pyramidal tract in the thalamus. Motor-evoked potentials (MEPs) were continuously recorded during neuroendoscopic resectioning of the tumors. Monitoring of MEP responses using depth electrodes in all 12 cases was successful. The minimum stimulus intensity threshold required to induce MEP responses was 3 mA. Gross total or subtotal resections were successful with this technique for all patients with glioma. No additional neurologic impairments were found after surgery in any of the cases. Continuous MEP measurement using depth electrodes can serve as a new monitoring technique for endoscopic resectioning of deep-seated brain tumors.