A Guide to the Performance of Transcranial Electrical Motor Evoked Potentials. Part 1. Basic Concepts, Recording Parameters, Special Considerations, and Application

In August 2002, the Food and Drug Administration (FDA) approved the use of a high-intensity multipulse stimulator to perform transcranial electrical motor evoked potentials (TCeMEPs) to monitor motor pathways in the brain and spinal cord. Since that time, this technique for monitoring pure motor pathways during surgeries that place these neural structures at risk has proceeded rapidly toward becoming the standard of care. This article is meant to be an introduction to the performance and use of this exciting new tool in the field of intraoperative neurophysiologic monitoring. Basic concepts regarding the need for this modality of monitoring, the anatomy of the pathways involved, and the mechanisms of waveform propagation are addressed. Stimulating and recording protocols are suggested for myogenic recordings, and illustrations of waveforms are provided. Special considerations specific to utilizing TCeMEPs, such as anesthetic requirements, risk factors, and other intraoperative considerations are reviewed. Lastly, alarm criteria are discussed and illustrative cases are presented. Appendices of electrode placements, case studies, sample forms, and other information are provided.