Spinal evoked potential in patients undergoing thoracoabdominal aortic reconstruction: a prognostic indicator of postoperative motor deficit.

We studied 76 patients who had thoracoabdominal aortic reconstruction between January 1981 and March 1991. Evoked potential monitoring of the spinal cord (peridural bipolar catheter stimulation at level L4-L5, recording via a second bipolar catheter at level Th4) was used to predict intraoperatively a possible motor deficit. There was a close linear correlation of r = 0.892 between postoperative motor deficit (normal, paraparesis, paraplegia) and the time from declamping to reappearance of the potential. Forty-three of 76 patients received prostaglandin E1 (5 ng/kg/min) for pharmacologic protection of the spinal cord 15 minutes before onset of clamping and through the entire clamping period. Patients with protection had a loss of their potential significantly later (20.2 min; p < 0.05) than those patients who had not received any pharmacologic treatment (15.2 min). Pharmacologic protection also resulted in a reduced incidence of postoperative neurologic deficit and paraplegia when compared with patients receiving no treatment (25% vs 5%). These data suggest that spinal evoked potentials may be very useful for monitoring during these hazardous cases. They also suggest that pharmacologic protection before clamping may help preserve the function of the spinal cord during aortic clamping.