We investigated whether propofol, a widely used anesthetic, injected into clamped aortic segments quickly attenuated transcranial spinal motor-evoked potential (MEP) amplitudes and protected against spinal cord injury during thoracoabdominal aortic surgery.Methods:
Eighteen beagle dogs were divided into three groups (n = 6, each group): group 1 (20 ml of saline, intra-aortic injection), group 2 (1.5 mg/kg of propofol, intravenous injection), and group 3 (1.5 mg/kg of propofol, intra-aortic injection). Aortic cross-clamping was performed for 30 min. In each group, MEP amplitudes were recorded before, during, and after aortic cross-clamping. Tarlov score and histopathological examination were used to evaluate the protective effects of intra-aortic propofol injections.Results:
MEP amplitudes in group 3 attenuated to a value that was 60% of the control in just a minute after aortic cross-clamping, but maintained 40% of the control value during aortic cross-clamping. However, MEP amplitudes in groups 1 and 2 gradually attenuated and almost disappeared. Groups 1 and 2 amplitudes were lower than those in group 3, 30 min after aortic cross-clamping (p ≪ 0.001). Twenty-four hours after ischemia, the Tarlov score in group 3 was 3.5 ± 0.5 and was higher than scores from groups 1 and 2, which were 0.5 ± 0.5 and 1.3 ± 1.2 (mean ± SD, p ≪ 0.001, and p ≪ 0.001), respectively. Histopathologically, normal spinal cord motor neurons in group 3 were preserved to a significantly greater extent than in groups 1 and 2 (p = 0.0031, and p = 0.0282, respectively). There was a strong correlation between Tarlov scores at 24 h and the number of normal motor neurons in the anterior horns of spinal cords (r = 0.897; p ≪ 0.001).Conclusions:
Intra-aortic propofol injections produce the quick suppression of MEP amplitudes and protect spinal cords from ischemia during aortic cross-clamping.