Spinal cord protection during thoracic & thoracoabdominal aortic aneurysm repair surgery

Abstract

The mortality and morbidity of extensive thoracoabdominal aorta replacement has improved markedly in recent years. Ischaemic spinal cord injury (SCI) remains the Achilles heel of open and endovascular descending thoracic and thoracoabdominal repair. Neurological outcomes have improved coincidentially with the introduction of neuroprotective measures. However, SCI (paraplegia and paraparesis) remains the most devastating complication. Blood supply to the spinal cord is complex. The vertebral arteries join to form the anterior spinal artery that supplies the motor areas of the cord, and 2 posterior spinal arteries that originate from the subclavian arteries supply the proprioceptive and sensory areas of the cord. Thoracic and lumbar segmental arteries contribute to both the anterior spinal artery, and an extensive paraspinous network feeds the paraspinous muscles. The anterior spinal artery is connected in multiple locations to epidural arteries and there are extensive connections between the intraspinous and paraspinous networks. Risk factors for spinal cord ischemia are aneurysm extent, Prolonged aortic cross-clamping, anemia, open surgical repair, prior distal aortic operations and perioperative hypotension. The cause of spinal cord injury during TAAA repair is multifactorial. A multitude of preventative and therapeutic approaches have therefore been developed, including distal aortic perfusion, maintenance of mean systolic arterial pressure, cerebrospinal fluid drainage, hypothermia, epidural cooling, selective spinal cord perfusion, sequential aortic crossclamping, reimplantation of intercostal arteries, identification and preservation of the artery of Adamkiewicz, and adjunctive pharmacologic therapies (steroids, mannitol, barbiturates, etc).