The evolution and progress of standard procedures for intraoperative nerve monitoring

The close proximity of the recurrent and external superior laryngeal nerves to the thyroid bed places them at risk of injury during neck endocrine procedures. Intra-operative nerve visual identification with structural preservation does not equate with the preservation of nerve functional integrity and the morbidity of neural injury resulting in post-operative vocal fold paralysis or voice change can be significant. As such, intraoperative neuromonitoring strategies for the recurrent laryngeal and, more recently, the external branch of the superior laryngeal nerve have evolved and have gained increasing attention from surgeons performing neck endocrine procedures worldwide. Currently, many head and neck and general surgeons use neural monitoring in at least some of their surgical cases. The support for intraoperative nerve monitoring (IONM) continues to grow at both an individual and organization level as the guidelines for standardization are published, prospective randomized controlled trials are reported, and structured training courses are established. This article will discuss the evolution and recent progress of standard procedures for intraoperative neuromonitoring of laryngeal nerves in thyroid and parathyroid surgeries.