[A case report of descending thoracic aortic aneurysm associated with anterior spinal artery syndrome despite no marked ESP changes].

A 67-year-old man underwent graft replacement for the descending thoracic aortic aneurysm with the aid of temporary external bypass. Intraoperative evoked spinal potentials (ESPs) were monitored to detect the spinal cord ischemia. Incomplete paraplegia with sensory dissociation was developed in this patient after surgery, despite well maintained ESPs throughout the aortic cross-clamping. ESPs have been widely used as a mean of detecting early impairment of spinal neural conduction during aortic surgery. However, ESPs are principally mediated through posterior and lateral column pathways and they are not always a reliable monitor to predict paraplegia in aortic surgery.