SPINAL CORD VASCULARITY. A HISTOPATHOLOGICAL AND ANGIOGRAPHIC STUDY OF THE EFFECTS OF THORACIC-LUMBAR AORTIC MOBILIZATION IN THE RAT

A clinical, histopathological and microangiographical study has been performed in eighty-three rats subjected to regional mobilization of the thoracic-lumbar aorta. Paralysis or paresis of the hindlimbs was observed in about one-fourth of the animals, predominantly in those subjected to an extensive mobilization of the aorta. A staged mobilization of the thoracic-lumbar aorta separated by an interval of 1 week not only minimized the incidence of neurological complications but the severity as well. The topographical distribution of the histopathological changes varied considerably both in the longitudinal and the transverse plane of the spinal cord in different experimental groups as well as individually in the same group of animals. Typical lesions were dorsal spinal cord infarction and arterial watershed lesions at the base of the dorsal horn, in addition to circumscribed necroses of the white matter corresponding fairly well to venous watershed zones. Microangiographically, the preservation of the caudal cord in cases with massive infarction of the thoracic cord, is believed to be due to a number of intramedullary arterial anastomoses. Usually a sufficient collateral blood supply to the spinal cord is readily available even in the case of comparatively extensive aortic mobilization. Enlargement and tortuosity of the spinal cord arteries and the intersegmental anastomoses immediately outside the spinal canal suggest that these vessels are the most important sources in the re-establishment of the collateral circulation.