We report the case of a patient who experienced near-infrared spectroscopy (NIRS)-detected transient regional cerebral desaturation during cardiopulmonary bypass for an operation to replace the aortic arch. Prompt institution of additional flow through an axillo-femoral graft was associated with restoration of regional cerebral saturation. The aortic surgery had no neurologic complications. Promptness in detecting and restoring cerebral perfusion appeared crucial in avoiding prolonged cerebral ischemia and reducing the likelihood of adverse neurologic events.