Spinal cord ischemia during aortic surgery is best detected by changes in which potential?

The detection of spinal cord ischemia during aortic surgery is most effectively monitored using the posterior tibial nerve somatosensory evoked potentials (SSEPs). These potentials are particularly sensitive to changes in the functional status of the spinal cord, especially in the lower segments, which is critical during procedures that may compromise blood flow to the spinal cord.

During aortic surgery, the risk of ischemia arises due to manipulation of vascular structures that supply blood to the spinal cord, particularly during clamping or retraction. The posterior tibial nerve SSEPs reflect the integrity of pathways connecting the lower limb nerves through the spinal cord, allowing for real-time monitoring of neural function. Anomalies or reductions in the amplitude or latency of these SSEPs can indicate diminished spinal cord perfusion, signaling the onset of ischemia.

In contrast, while median nerve SSEPs and tibial nerve compound action potentials provide valuable information about upper limb and motor pathways, respectively, they are less direct indicators of spinal cord health in the context of thoracoabdominal aortic surgery. The lumbar N20 spinal cord potential, although important for assessing lumbar spine function, does not offer the same level of sensitivity to ischemic changes as the posterior tibial nerve SSEPs during this type