Spinal Cord Protection / Monitoring

A major challenge in operations to replace the descending thoracic or thoracoabdominal aorta is preventing injury to the spinal cord. The spinal cord can be at risk when replacing the descending aorta due to interruption of its blood supply, which comes partially from intercostal arteries from the descending aorta itself. As a result of interruption of this blood supply, pressure in the fluid around the spinal cord may increase and, in turn, put pressure on the spinal cord and lead to neurologic complications. We employ a number of measures that help us monitor the spinal cord during the surgery and prevent spinal cord injury.

CSF Drainage
We routinely place a catheter in the space around the spinal cord (an epidural catheter) which monitors the pressure of the cerebrospinal fluid (CSF) and allows us to drain fluid from the space if the pressure rises. This catheter is placed before the operation, and left in place for approximately 2-3 days, in order to provide safe perioperative spinal cord monitoring.

Distal Perfusion
During the operation, the patient is usually placed on a form of partial cardiopulmonary bypass support. This means of support allows the heart to continue to beat on its own, while maintaining blood flow and perfusion to the lower part of the body while the aortic replacement is taking place.

MEP / SSEP Monitoring
For all descending aortic operations in our practice, we use comprehensive neurologic monitoring equipment that measures both motor and somatosensory evoked potentials (MEP / SSEP). A non-invasive monitoring system is in place throughout the surgery and allows the surgeon to be aware of any changes in the neurologic function in real time. This facilitates changes in strategy during the surgery to lessen the risk of neurologic damage.

Hypothermia
All descending aortic surgery is performed with the use of moderate systemic hypothermia, which involves cooling the patient, lowering metabolic work and decreasing the risk of neurologic injury.