Comparison of Outcomes of Intra-operative Neuromonitoring of Recurrent Laryngeal Nerve Versus Visualisation Alone during Thyroidectomies: A Singapore Experience

Abstract

Introduction: Although intra-operative neuromonitoring (IONM) has become commonly used to identify the recurrent laryngeal nerve (RLN) during thyroid surgeries, its value is still debatable. This study aimed to evaluate the outcomes of thyroid surgery using IONM versus visualisation alone (VA). Methods: We conducted a retrospective analysis of all the open thyroidectomies performed by the otolaryngology department in a tertiary institution in Singapore (Khoo Teck Puat Hospital) from 1 January 2014 to 31 December 2018. There were 301 nerves-at-risk (NAR), 139 in the IONM group and 162 in the VA group. The primary outcome measure was the incidence of RLN injury and the secondary outcome measure was operative duration. Results: There were 33 NAR with immediate post-operative RLN injury, of which 7 had permanent (>6 months) injury. There were minor improvements in the respective rates of immediate and permanent injury in the IONM group (7.9%, 0.7%) compared to the VA group (13.6%, 3.8%), but these were not statistically significant (P=0.14, 0.13). The average operative duration of total thyroidectomies in the IONM group was 37 minutes shorter than in the VA group, but the difference was not statistically significant (P=0.40). Conclusion: The current study shows that the use of intra-operative neuromonitoring shows a tendency towards better RLN outcome and operative duration for total thyroidectomies, but the study may be too small to demonstrate a statistical difference. Keywords: Nerve monitoring, otorhinolaryngology, surgery, thyroid, vocal cord paralysis