In an effort to reduce the incidence of spinal cord injury following resection of descending thoracic and thoracoabdominal aneurysms, we have developed a multifaceted approach to maximize spinal cord perfusion which involves monitoring spinal cord function using somatosensory evoked potentials (SSEPs) intraoperatively and postoperatively. Intercostal and lumbar intersegmental vessels are sacrificed in a gradual stepwise fashion before the aneurysm is incised: none of these vessels is reattached unless SSEPs are abnormal following temporary occlusion, and this has not yet been observed. Postoperative spinal cord perfusion is maximized by keeping arterial pressure high and by draining cerebrospinal fluid if intrathecal pressure is elevated. Only two cases of permanent paraplegia have developed in 95 patients. Multivariate analysis showed extensive aneurysms (spanning 10 or more intersegmental arteries) and a history of smoking as the only significant risk factors for development of spinal cord injury.