Objective: This study was designed to test the hypothesis that detection of the location of the major artery supplying the spinal cord, that is, the artery of Adamkiewicz or the great radicular artery (GRA), with angiography would help prevent paraplegia. Knowing which intercostal artery provides this important branch would enable prompt, focused revascularization.
Method: The surgical outcome in 131 patients with Crawford extent 1 and 2 degenerative aneurysms and 69 patients with descending thoracic aortic dissection was correlated with findings on selective intercostal arteriograms. Angiographic maneuvers were done with care, and the procedures were aborted if there was loose or "shaggy" mural thrombus, significant tortuosity, or difficulty entering each dissection channel. No attempts were made to find major contributions proximal to T6. Subarachnoid drains were placed in all patients, and all but five patients underwent distal aortic perfusion with controlled cooling to 32 degrees F. Five patients underwent cold circulatory arrest, enabling replacement of the distal aortic arch. We defined paraplegia simply as the inability to walk at hospital discharge, paraparesis as impaired ambulation, and both as having spinal cord dysfunction (SCD).
Results: A GRA was found in 65 (43%)of the 151 patients studied. Of the 65 patients with the GRA identified, SCD developed in 3 (4.6%) patients. Thirteen of 135 (9.6%) patients in whom the GRA was not identified, either because they were not studied or were studied and the GRA was not found, developed SCD (P =.35) However, when the GRA was identified, SCD occurred only in the group with aortic dissection. None of the 45 patients with degenerative aneurysms with the GRA identified had SCD, compared with 9 of 55 (16%) patients studied but without a GRA found (P =.01).
Conclusion: The approach with selective intercostal angiography did not improve overall results. One third of our patients were not studied, and they fared as well as patients who were studied and the GRA was localized (not studied, 4 of 49, 8% with SCD; GRA localized, 3 of 65, 5% with SCD; P =.8). However, when the GRA was found, SCD occurred only in patients with aortic dissection. The studies confirmed the concept that the existence of mural thrombus in degenerative aneurysms results in the occlusion of many intercostal arteries, leaving those remaining patent to supply rich vascular watersheds through acquired collateral channels. As a result, in the group of patients with degenerative aneurysms, the identification of the critical intercostal artery allows focused reimplantation with uniform success. This is not the case in patients with aortic dissection. In those patients, most intercostal vessels remain patent, such that the insertion of one pair is insufficient to supply the paravertebral plexus and the spinal cord. Finally, failure to identify the GRA angiographically with our methods does not provide assurance that the GRA does not exist. Therefore negative findings did not provide license to ligate all intercostal arteries.