A major disadvantage of monitoring only posterior tibial nerve SSEP during scoliosis surgery is the inability to?

Monitoring solely the posterior tibial nerve somatosensory evoked potentials (SSEPs) during scoliosis surgery does have significant limitations, particularly when it comes to assessing ischemic injury to the anterior spinal cord. The posterior tibial nerve primarily assesses the function of the sensory pathways that project through the posterior columns of the spinal cord. However, it does not effectively monitor the anterior portion of the spinal cord, which is critical in evaluating motor function and anterior spinal cord ischemia.

Ischemic injury to the anterior spinal cord can occur due to various mechanisms during scoliosis surgery, particularly with the positioning and mechanical manipulation of the spine. The anterior spinal artery supplies blood to the anterior two-thirds of the spinal cord, and damage to this area could lead to motor deficits and significant functional impairments. Because the posterior tibial nerve SSEPs do not reflect the functional integrity of the anterior spinal cord trajectories, reliance on this monitoring modality alone can result in an inadequate assessment of possible ischemic injury.

In conclusion, monitoring only the posterior tibial nerve SSEPs leaves a gap in the ability to detect anterior cord ischemia, making it a critical disadvantage during scoliosis surgeries where maintaining the integrity of the entire spinal cord is paramount for patient outcomes.