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Evoked Potentials: Aortic Surgery

There are multiple modalities currently used in practice to prevent paraplegia after aortic surgery including distal aortic perfusion, lumbar drains to monitor ICP and drain CSF, reimplantation of intercostal arteries, and moderate hypothermia. Neurophysiologic monitoring via somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) can provide a means of predicting neurologic deficits intraoperatively.

SSEPs and MEPs have poor sensitivity for immediate neurologic damage when the changes in potentials are reversible after changes are made to improve spinal cord perfusion. These reversible changes are not correlated with immediate neurologic deficit.

If SSEPs or MEPs remain normal, the negative predictive value for immediate neurologic damage is high and there is a very low probability that these patients will awake with neurologic deficit.

SSEP and MEP monitoring are highly correlated when changes seen intraoperatively were irreversible. This is highly associated with immediate neurologic damage on awakening.

SSEPs are not a good predictor of delayed neurologic deficit as the pathophysiology of delayed deficits is different than those seen immediately postoperatively.


  1. Vaughn SB, Lemaire SA, Collard CD. Case Scenario: Anesthetic Considerations for Thoracoabdominal Aortic Aneurysm Repair. Anesthesiology 11 2011, Vol.115, 1093-1102 PubMed Link
  2. Galla JD, Ergin M, Lansman SL, et al. Use of somatosensory evoked potentials for thoracic and thoracoabdominal aortic resections. Ann Thorac Surg. 1999; 67(6): 1947-52 PubMed Link

Other References

  1. Loubser PG, Sheinbaum R. Neurophysiologic Monitoring during Thoracoabdominal Aortic Aneurysm Surgery. Anesthesiology 6 2012, Vol.116, 1397-1398 Link