Prevention of paraplegia secondary to operations on the aorta.

Prevention of paraplegia during operations on the aorta requires knowledge of the blood supply to the spinal cord. The great radicular artery of Adamkiewicz (RAD) plays a major role in the supply to the anterior spinal artery which nourishes the anterior two-thirds of the cord. The RAD usually arises from an intercostal artery between T9-T12 but may arise higher or in 10% of patients from a lumbar artery. Temporary interruption of flow by crossclamping, hypotension, or permanent interruption of the RAD are factors in the etiology of paraplegia. In resection of descending thoracic aortic aneurysms, the thoracic aorta should not be crossclamped without an external bypass. The bypass should be nonthrombogenic to avoid necessity for anticoagulation and attendant hemorrhagic problems. Bypass flow is ideally controlled by a pump with continuous monitoring of the proximal and distal pressures to provide normal distal flow to the cord. As many intercostal and high lumbar arteries as possible should be preserved by retaining the distal posterior wall of the aneurysm. Preoperative selective catheterization of the distal thoracic intercostal or proximal lumbar vessels can delineate critical supply to the cord and should become part of the routine workup of patients being considered for surgery of the distal thoracic and thoraco-abdominal aorta. Knowledge of the location of the RAD may permit its avoidance or reinsertion into a graft. Avoidance of the RAD may be particularly applicable with infrarenal aneurysms when a large lumbar artery is seen just above or below a renal artery. Here, avoidance of all but brief suprarenal clamping and resection of the aneurysm below the feeding RAD may help to avoid paraplegia.