Somatosensory Evoked Potentials During Exclusion and Reperfusion of Critical Aortic Segments in Thoracoabdominal Aortic Aneurysm Surgery

Abstract

Forty-three patients undergoing repair of a thoracoabdominal aortic aneurysm were monitored to evaluate spinal cord ischemia, as evidenced by somatosensory evoked potentials (SEPs). All patients were operated on using left heart bypass. in 34 patients (80%), staged clamping was used. Except for cerebrospinal fluid (CSF) drainage in 15 patients (asyo), no other protective measures to preserve spinal cord function were used. The overall lncidence of immediate onset paraplegia was 7%, and of immediate onset paraparesis was 5%; neither was limited only to those patients In whom potentials were lost. In 18 patients (42%), no change in the evoked potentials occurred; one of these patients (5%) awoke paraplegic after operation, and two others had a delayed onset paraplegia. In 13 patients (30%), evoked potentials were lost despite adequate perfusion; in 12 of them, potentials returned gradually, with one immediate paraplegia (8%), and in one potentials did not return at all, with subsequent immediate paraplegia (100%). In 12 patients (28%), evoked potentials decreased without being lost completely, and then recovered; in this group there were no immediate parapleglas. No relationship could be demonstrated between the extinction time, the recovery time, or the duration of loss of evoked potentials with postoperative neurological outcome. lntraoperative monitoring of SEPs is a good indicator of spinal cord ischemia, although we found a 5% incidence of false negatives. SEP monitoring offers an improvement in surgical strategy, and allows safer operations for thoracoabdominal aneurysms. (J Card Surg 7994;9:692–702)