Background: Paraplegia is a devastating complication of spinal cord ischemia following descending thoracic and thoracoabdominal aortic surgery. The incidence of spinal cord ischemia ranges from 8-22%. The mechanisms are multifactorial but are related to ischemia-reperfusion injury.
Case Description: A 61-year-old Hispanic male presented to the emergency department complaining of hemoptysis. In 1974, he underwent an aortic isthmus interpositional graft for a traumatic aneurysm of the thoracic aorta. An endovascular graft was placed in 2014 for an aorto-bronchial fistula. In 2015, the patient was started on suppressive antibiotics for a chronic aortic graft infection. Surgery was planned for a complete resection of the indwelling grafts with extra-anatomic bypass. After induction, we performed remote ischemic preconditioning of the left upper extremity for three five-minute periods. A lumbar drain was placed and cerebrospinal fluid was drained intermittently throughout the procedure. The surgeons performed a median sternotomy and laparotomy. Bypass grafts were placed from the low ascending aorta to the innominate and left common carotid artery, and from the low ascending aorta to the supra-celiac aorta. During this time, the innominate artery, left common carotid, and supra-celiac aorta were cross-clamped intermittently. The distal ascending aorta was ligated and the sternotomy closed. The patient then became hypertensive followed immediately by profound hypotension with 3L of blood output from his chest tubes. The sternotomy was emergently reopened and manual cardiac massage was performed and the patient was resuscitated. An aortic tear at the proximal graft anastamosis was repaired and the sternotomy closed. The patient was placed in right lateral decubitus for a thoracotomy and the remaining aortic graft was resected. He was brought to the ICU intubated and sedated. The patient awoke four hours postoperatively with lower extremity paraplegia and intact sensation. His symptoms improved with drainage of CSF and all neurological symptoms resolved following arterial blood pressure augmentation.
Discussion: The potential for severe morbidity and mortality demands that prevention of spinal cord ischemia be a part of the anesthetic plan for all thoracic or thoracoabdominal aortic repairs. Aortic cross-clamping causes decreased distal MAP and increased CSF pressure which lowers spinal cord perfusion pressure. Perioperative hypotension is also a major factor implicated in spinal cord ischemia. Reperfusion after ischemia produces oxygen free radical species and proinflammatory cytokines which worsen the initial injury. Several preoperative interventions and pharmacological agents have been shown to provide some protection from ischemic injury however further investigation is needed as no method has been ultimately successful. Anesthetic management should include identification of patients at risk for spinal cord ischemia, maintenance of spinal cord perfusion pressure, detection of neurological deficits, and facilitation of lumbar CSF drainage. Additional measures can aim to improve ischemic tolerance, reduce spinal cord oxygen demand, scavenge free radicals, decrease inflammation, and mitigate neuronal injury.
