Effective tool or necessary evil: intraoperative monitoring during thoracic aneurysm repairs.

Background: The aim of our study was to analyze the neurophysiologic monitoring method with regard to its potential problems during thoracic and thoracoabdominal aortic open or endovascular repair. Furthermore, preventive strategies to the main pitfalls with this method were developed.

Methods: Between November 2000 and May 2007, in 97 cases, open surgery or endovascular stent graft implantation was performed on the thoracic or thoracoabdominal aorta. Intraoperatively, neurophysiologic motor and somatosensory evoked potentials were monitored.

Results: Our cases were divided into four groups: event-free patients with normal potentials (A, 63 cases), those with correlation of modified evoked potentials and neurological outcome (B, 14 cases), those with false-positive or false-negative results (C, 4 cases), and those with medication interaction or technical issues (D, 16 cases). We observed a sensitivity of 93% and a specificity of 96% for the neurophysiologic monitoring.

Conclusions: Monitoring spinal cord function during surgical and endovascular interventions on the thoracic and thoracoabdominal aorta is necessary. It can be made more effective by precisely analyzing the interference factors of the neurophysiologic monitoring method itself. Successful strategies of immediate troubleshooting could be identified.