Continuous Vagal Nerve Monitoring is Dangerous and Should not Routinely be Done During Thyroid Surgery

Introduction: Laryngeal nerve monitoring has been increasingly embraced as a mechanism for mitigating the risk of nerve damage during thyroid and parathyroid surgery. Vagal nerve monitoring has recently been introduced as a potentially increased level of nerve integrity scrutiny. We sought to define the risks and benefits of this technology in a prospective analysis of a series of patients undergoing neck endocrine surgery. Setting: High-volume academic endocrine surgery practice. Methods: A prospective, non-controlled trial of continuous vagal nerve monitoring (CVNM) in a projected cohort of 20 non-randomly selected patients undergoing thyroid and parathyroid surgery was planned. A commercially available nerve monitoring system with automatic periodic stimulation was utilized for both laryngeal nerve monitoring and CVNM. Demographic data were obtained, and outcome variables included surgical procedures performed, pathology, complications, incremental time required to achieve CVNM, and benefits of monitoring and stimulation. Results: The patient accrual was aborted after 9 surgeries (12 nerves monitored) because of two serious adverse events (hemodynamic instability and reversible vagal neuropraxia attributable to the monitoring apparatus). No other complications occurred. The time to establish monitoring ranged from 3 to 26 min, with a median of 6 min (representing 2.9-12.2 % of the total surgical procedural time). The stimulation clamp became dislodged 11 times in 5 cases and was replaced in 7 of those instances. Benefits of CVNM included recognition of reduced amplitude and increased nerve latency in two patients. Conclusions: We report the first evidence that CVNM may cause serious patient harm. This novel approach is invasive and threatens patient safety. Although it may occasionally provide meaningful information, the risk-benefit ratio does not favor widespread adoption.