Transcranial magnetic evoked potentials used to monitor the spinal cord during neuroradiologic angiography of the spine.

A current topic in intraoperative monitoring of the spinal cord is the inability of the somatosensory evoked potentials (SSEP) to adequately document anterior spinal cord function. Transcranial magnetic stimulation (TMS) of the cortex for assessing corticospinal (efferent) pathways is a developing modality. The authors demonstrate a potential application of TMS as a monitoring medium for use in the neuroradiology suite. Limitations of intraoperative applications of cortical magnetic stimulation associated with cortical suppression are caused by anesthetics and neuromuscular blockers. These limitations generally are not an issue in the neuroradiology suite. In this report, motor improvement was correctly predicted by magnetic evoked potential amplitudes, whereas an SSEP remained unchanged during neuroradiologic angiography.