Continuous intraoperative neural monitoring in thyroid surgery: a Mexican experience

Intraoperative continuous neural monitoring (C-IONM) during thyroid surgery has been recognized as a useful tool to identify and confirm recurrent laryngeal nerve integrity. The aim of the present study is to analyze electromyographic features and thresholds for normal vocal fold function in our initial experience with C-IONM in thyroid surgery. C-IONM was utilized in 57 patients who underwent thyroid surgery between July 2012 and December 2015. EMG parameters were analyzed looking for potential predictors of postoperative vocal fold dismotility. There were 54 females (94.7%) and 3 males (5.3%) with a mean age of 46.7 ± 11.6 years. C-IONM was successfully registered in 89 of 107 nerves at risk (83.1%). Mean basal amplitude was 727.31 ± 471.25 μV and mean final amplitude was 650.27 ± 526.87 μV (P = 0.095, CI 95% 13.83-167.91). Mean basal latency was 5.23 ± 1.42 mS and mean final latency was 5.18 ± 1.50 mS (P = 0.594, CI 95% 0.39-0.24). Four patients had transient postoperative vocal fold paresis. None of these four patients had loss of signal (LOS), three had transient decrease in amplitude, and one had a normal registry throughout the operation. C-IONM is a useful tool to identify patients in whom intraoperative RLN is at risk during surgery. Final amplitude above 500 μV and no LOS is associated with RLN integrity and normal postoperative vocal fold function.