Prognostic value of improved intraoperative motor evoked potentials. A case report.

UNLABELLED: This unusual case involves intraoperative registration of improved motor evoked potentials accompanied by postoperative improvement of the motor status. CASE REPORT: A 51-year-old patient undergoing surgery for a right postcentral glioma was first submitted to phase reversal of somatosensory potentials for intraoperative localization of the central sulcus. During subsequent monopolar electric stimulation of the precentral gyrus, motor evoked potentials (MEPs) could not be recorded initially but only following extirpation of the tumor fraction in the central sulcus. The amplitudes of the registered potentials increased during the further clinical course. The preoperative arm-preponderant hemiparesis already improved on the first postoperative day. CONCLUSION: This intraoperative electrophysiological observation correlated with the postoperative neurological status, thus documenting functional recovery of the motor system through the intervention.