Intraoperative somatosensory evoked responses recorded during onset of the anterior spinal artery syndrome

Somatosensory evoked responses may be used during operations on the thoracic aorta to monitor spinal cord function. A patient is described in whom the evoked responses were well maintained for the first 20 minutes of aortic occlusion and briskly returned to baseline configuration after reestablishment of aortic flow. Nonetheless, the patient was left with paralysis of the lower extremities consistent with the diagnosis of anterior spinal artery syndrome.