Transcranial Motor-Evoked Potentials

Abstract

Motor-evoked potentials (MEPs) are the most recent addition to routine intraoperative neurophysiologic monitoring (IOM). Enthusiastic reports of improved outcomes obtained with the use of somatosenory evoked potential (SEP) monitoring, primarily for scoliosis procedures in children and young adults, were quickly followed by case reports of isolated postoperative motor injury without sensory changes [ 1 ] . These reports reflected the reality of the anatomy and physiology of motor/sensory pathways. MEP and SEP pathways are located in different topographic and vascular regions of the cerebral cortex, brainstem, and spinal cord. Motor functional pathways are more sensitive to ischemic insults than SEP pathways [ 2 ] .