Last update:
11-Nov-2004

OBJECTIVE Ischemic preconditioning has been found to protect various organs from subsequent ischemic insult. In this study it was investigated whether late ischemic preconditioning reduces spinal cord injury after descending thoracic aortic occlusion.

METHOD The experiment used 24 pigs (27–30 kg), randomly divided into four groups, I, II, III and IV. The group I (n=4) animals underwent a sham operation, group II (n=4) underwent aortic occlusion for 20 minutes, group III aortic occlusion for 35 minutes and in group IV (n=8) aortic occlusion for 20 minutes and 48 hours later for 35 minutes (late ischemic preconditioning). Aortic occlusion was performed by using two occlusion balloon catheters under fluoroscopic guidance at T6–T8 and at the aortic bifurcation. The neurologic evaluation was made according to the Tarlov scale (0–4) at 24, 48 and 120 hours. Lumbar spinal cord specimens were examined histologically with hematoxylin-eosin stain at 120 hours, the number of neurons was counted and the presence of inflammation was scored (0–4, 4: no inflammation). Statistical analysis was performed using the Kruskal-Wallis test.

RESULTS Group IV had a better neurologic outcome at 24, 48 and 120 hours in comparison to group III (P<0.001), although at 120 hours after the end of the experiment the neurologic outcome was worse than that at 24 hours (P=0.014). Histologic findings were proportional to the neurologic test scores, with the more severe and extensive gray matter damage in the group III animals (number of neurons P<0.001, and grade of inflammation P<0.001).

CONCLUSIONS Ischemic preconditioning (late phase 48 hours after the first occlusion) reduces spinal cord injury after descending thoracic aortic occlusion, as estimated by the Tarlov score and histopathological appearances.

Key words: Aneurysm, Aortic occlusion, Aortic occlusion ischemia, Preconditioning, Spinal cord.