Continuous intraoperative neuromonitoring for thyroid cancer surgery: A prospective study

Laryngoscope Investig Otolaryngol. 2019 Jul 18;4(4):455-459. doi: 10.1002/lio2.290. eCollection 2019 Aug.


Objective: We evaluated the utility of continuous intraoperative neuromonitoring (CIONM) during surgery for thyroid cancer (TC) in an educational university hospital.

Study design: Prospective observational study.

Methods: During the period April 2016 to March 2017, 43 patients who underwent standardized surgery with CIONM were prospectively included: 5 men and 38 women, 24-87 years old (median 52 years); 23 lobectomies and 20 total thyroidectomies with node dissection were conducted. Thirty-six operations were performed by a supervising surgeon, and seven were performed by trainees.

Results: Temporal vocal cord paresis (VCP) was identified in 9 of 63 nerves at risk (14.3%) by postoperative laryngoscopy. VCP was not related to clinical factors including the surgeon's experience or the severe nerve stress demonstrated by CIONM. A significant relation only between VCP and loss of signal (LOS) was demonstrated (P = .002). The recovery of VCP was rapid (<1 month) in patients with global injury even when LOS was demonstrated, but was prolonged in patients demonstrating obvious segmental nerve injury and LOS.

Conclusion: The present standard protocol of CIONM was useful to some extent to protect prolonged VCP, but not enough to detect every nerve stress causing VCP during TC surgery. On the other hand, CIONM is a promising method that could contribute surgical education at training hospitals enabling the instant confirmation of the procedure safely.

Levels of evidence: 3b.

Keywords: Continuous intraoperative neuromonitoring; recurrent laryngeal nerve injury; surgical education; thyroid cancer surgery.