Neuromonitoring in endoscopic and robotic thyroidectomy

Intraoperative neuromonitoring (IONM) has proven effective for intraoperative verification of RLN function in the conventional thyroid surgery. However, no studies have performed a systematic evidence-based assessment of this novel health technology in endoscopic and robotic thyroidectomy. Evidence-based criteria were used in a systematic review of relevant literature for years 2000-2015. Four electronic databases (CENTRAL, MEDLINE, Cochrane and EMBASE) were used to retrieve relevant reports published from January 1, 2000 to September 1, 2016. The search terms included "endoscopic thyroidectomy", "robotic thyroidectomy", "IONM", "continuous IONM (CIONM)", "neural monitoring", "recurrent laryngeal nerve monitoring", and "superior laryngeal monitoring". The following data were retrieved from eligible studies of patients undergoing endoscopic or robotic thyroidectomy: objective of study, design and setting of study, population, intervention examined, quality of data, follow-up and dropout rate, risk of bias, and outcomes assessed. Of 160 studies retrieved, only 9 (5%) studies used IONM. Eight studies reported 522 nerve at risk (NAR) with IONM. Only three were prospective randomized studies. Reports of IONM endoscopic and robotic procedures included their use for re-surgery and use in both benign and malignant cases. None of the IONM endoscopic procedures involved bilateral palsy. Two studies reported the use of a staged strategy. The rates of recurrent laryngeal palsy were 0-3.6% for transient and 0-0.4% for permanent. Only 30% of the studies performed vagus nerve stimulation, and only 25% performed superior laryngeal nerve monitoring. In addition to the use of IONM as an assistive technology for navigating the anatomy in challenging procedures such as endoscopic and robotic thyroidectomy, IONM has potential use as a routine adjunct to the conventional video-assisted nerve identification in thyroidectomy.