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 th e thoracic aorta, For preventing this complication, we employed evoked spinal cord potentials elicited by direct stimulation of the cord (ES Ps-dsc) during operations on 83 patients with various aortic lesions ( 37 dissecting and 46 cases of nondissecting aneurysms, 35 descending a nd 48 thoracoabdominal aortic aneurysms), All of the patients had some form of circulatory adjunct during aortic cross-clamping, Of the 83 p atients, 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 observ ed: (1) no change (n=57), (2) change with return (n=15), (3) change wi th inconsistent return (n=6), (4) change without return (n=5), ''Delay ed'' paraplegia occured in two patients with ''no change'' and ''chang e with return'' response (3%), ''immediate'' paralysis occured in thre e and ''delayed'' paraplegia occured in one of those with ''change wit h inconsistent return'' response (67%), and all of those with ''change with inconsistent return'' response (67%), and all of those with ''ch ange 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.