Relationship between posttraumatic ischemia and hemorrhage in the injured rat spinal cord as shown by colloidal carbon angiography.

Adult female Wistar rats underwent extradural clip compression injury of the spinal cord at T-1. A force of 40 g was applied for 1 minute; this moderately severe injury renders animals paraparetic. We performed colloidal carbon angiography with Aquablak on four animals at 15 minutes, 2 hours, and 24 hours after injury. The entire spinal cord was then removed, frozen, and sectioned serially at 250 micron. The sections were examined microscopically for patterns of ischemia and hemorrhage at the site of compression injury and at adjacent and remote sites in the spinal cord. There was a marked lack of filling of the arterioles, capillaries, and venules at the injury site. In addition, there was a specific anatomical distribution of the ischemic areas in that ischemia of the white matter occurred in areas supplied by arteries that traversed adjacent hemorrhagic gray matter. For example, ischemia of the ventral funiculus was consistently seen adjacent to hemorrhage in the ventral gray matter. Similarly, ischemia of the dorsal white columns was related to hemorrhagic lesions surrounding the feeding vessels in the dorsal gray matter. This study also demonstrates the usefulness of a new colloidal carbon suspension (Aquablak) for documenting the pathophysiology of posttraumatic ischemia of the spinal cord. The results suggest that ischemic lesions in the white matter are anatomically related to hemorrhagic lesions in the gray matter. The pathophysiology of this relationship is unknown, but may include thrombosis, vasospasm, or direct injury of the feeding vessels.