Continuous intraoperative monitoring of vagus and recurrent laryngeal nerve function in patients with advanced atrioventricular block.

Abstract

Intraoperative neuromonitoring of recurrent laryngeal nerve function after stimulation of the vagus nerve has been embraced as a risk minimization tool in thyroid surgery to prevent recurrent laryngeal nerve injury. Because this technology is increasingly used in an elderly and sicker population, the present study was conducted to determine the safety of this method in patients with second- or third-degree atrioventricular block. This study aimed at evaluating the feasibility and safety of continuous intraoperative neuromonitoring (CIONM) in patients with second- or third-degree atrioventricular block. A total of six patients (12 nerves at risk), accounting for 0.3% of all 1800 patients (3049 nerves at risk) who underwent thyroid surgery during the study period, were found to have second- or third-degree atrioventricular block. All these patients maintained normal systolic and diastolic blood pressures; heart rate; and peripheral arterial oxygen saturation before, during, and after CIONM. No clinically relevant changes in heart rate or blood pressure, cardiac arrhythmia, or other hemodynamically important events were noted despite careful monitoring of these patients. There was no interference between the biphasic waveform of the vocal muscle electromyogram and the spikes generated by the implanted cardiac pacemakers. Outcomes were uneventful with normal vocal fold and parathyroid gland function. Within the limitations of this series and considering experimental, animal, and human data, continuous IONM of the vagus nerve at ≤2Hz seems to be reasonably safe. Additional research is warranted to confirm these results in larger groups of patients with advanced atrioventricular block.