Combination of Myogenic and Neurogenic Motor Evoked Potential Monitoring During Thoracoabdominal Aortic Surgery

A 64-year-old woman was evaluated for thoracoabdominal aortic aneurysms (TAAAs). Preoperative computed tomography showed a TAAA extending from the level of the diaphragm to the renal arteries. The Adamkiewicz artery (AKA) arose at the Th10 level, close to the aneurysm, and an abdominal aortic prosthesis and left iliac artery aneurysm were detected. Myogenic and neurogenic motor evoked potentials (MEPs) were monitored during the surgical repair of the TAAA, and there were differences between the two types of MEPs during surgery. Both MEPs fell below 50% of their baseline levels during surgery, which suggested critical ischemia, but the decrease in the myogenic MEP occurred at a different time from the decrease in the neurogenic MEP. A time-course analysis suggested that AKA reimplantation was unnecessary and all intercostal arteries were ligated. Both MEPs recovered completely by the end of surgery and there were no postoperative neurologic deficits. Our findings suggest that the combination of myogenic and neurogenic MEP monitoring is helpful in evaluating spinal cord injury during the surgical repair of TAAAs.