The reliability of evoked spinal cord potentials elicited by direct stimulation of the cord as a monitor of spinal cord ischemia during temporary occlusion of the thoracic aorta.

Paraplegia is a severe and disastrous complication of operations on the thoracic aorta. For preventing this complication, we employed evoked spinal cord potentials elicited by direct stimulation of the cord (ESPs-dsc) during operations on 83 patients with various aortic lesions (37 dissecting and 46 cases of nondissecting aneurysms, 35 descending and 48 thoracoabdominal aortic aneurysms). All of the patients had some form of circulatory adjunct during aortic cross-clamping. Of the 83 patients, three had "immediate" paraparesis and five had "immediate" paraplegia, whereas three other patients had "delayed" paraplegia. During operation, four types of ESPs-dsc response pattern were observed: (1) no change (n = 57), (2) change with return (n = 15), (3) change with inconsistent return (n = 6), (4) change without return (n = 5). "Delayed" paraplegia occurred in two patients with "no change" and "change with return" response (3%), "immediate" paralysis occurred in three and "delayed" paraplegia occurred in one of those with "change with inconsistent return" response (67%), and all of those with "change with inconsistent return" response (67%), and all of those with "change without return" response developed "immediate" paraplegia (100%). We conclude that intraoperative monitoring of spinal cord function utilizing ESPs-dsc is a good indicator of spinal cord ischemia and we can improve the outcome according to its changes.