Intraoperative neurophysiologic monitoring in thoracoabdominal aortic aneurysm repair: A single-center prospective study

Intraoperative neuromonitoring (IOM) allow the assessment of spinal integrity during thoracoabdominal aneurysm (TAAA) surgery, giving the opportunity to predict or help to prevent spinal ischemia (SCI). The reliability of IOM depends on excluding confounding factors and on warning criteria. Our aims were to investigate the sensitivity and specificity of IOM for SCI and to verify if the study of compound motor action potential (CMAP) is reliable in the identification of limb ischemia and improve IOM sensitivity for SCI. One-hundred consecutive patients (mean 64.3 yrs) undergoing TAAAs surgery between February 2016 and March 2018 were studied prospectively. IOM included motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs), popliteal potentials and CMAPs. MEPs and SEPs were recordable in 99% of cases. MEPs showed transient changes in 49.5% and persistent decrease in 16.2% (3% unilateral). All of 4 patients with persistent bilateral MEPs deterioration and without alteration of peripheral potentials or arm MEPs developed paraplegia. Persistent bilateral MEPs changes, especially without concurrent peripheral alterations, are at high risk of SCI and justify prompt interventions for maximize spinal perfusion. The improvement of the accuracy in the identification of peripheral ischemia could help to clarify which MEPs alterations correlate with neurologic deficits.