Neuromonitoring in Thyroidectomy Is neuromonitoring useful in preventing recurrent laryngeal nerve injury? Wong Chun Lam United Christian Hospital Joint Hospital Surgical Grand Round 18th July 2015

Introduction Recurrent laryngeal nerve (RLN) injury – one of the most significant complications in thyroidectomy Visual identification of RLN Incidence of RLN palsy Transient: 3% Permanent: 1%

Mode of RLN Injury Traction / stretching Thermal Ischemia due to over-skeletonization Direct Transection

Neuromonitoring Firstly described since 1960s Continuous discussion on its role in reducing risk of RLN injury

Methods of Neuromonitoring Electromyography (EMG) Needle electrodes inserted to effector muscle Surface electrodes on endotracheal tube contacting with vocal cord

Stimulating probe emits electric current when activited RLN stimulated and vocalis muscle activity registered by monitoring machine

Use of Neuromonitoring RLN mapping and identification Aiding RLN dissection Predicting post-operative vocal cord function High negative predictive value (92-100%) Helps operation planning in total thyroidectomy Loss of signal upon stimulation of first side RLN  defers contralateral thyroidectomy as second operation after functional recovery of ipsilateral vocal cord

Disadvantage of Neuromonitoring Time in setup the monitoring system Cost Endotracheal tube: HKD 3,500 Monitoring system: HKD 300,000 Surgeon’s dependence on neuromonitoring

Current Evidence

Search Strategy Literature search using Pubmed with keywords: thyroidectomy, recurrent laryngeal nerve, monitor From 2005 till now 10 comparative studies 4 RCTs 4 meta-analyses I have performed a literature search on Pubmed using keywords thyroidectomy, recurrent laryngeal nerves and monitor. What I could find is 10 comparative studies, 4 randomized controlled trials and 4 meta-analysis related to the topic.

Randomized clinical trial of visualization versus neuromonitoring of recurrent laryngeal nerves during thyroidectomy M. Barczynski, A. Kontrurek, S. Cichon 2000 nerves-at-risk Visual Identification Alone (n = 1000) Visual Identification + Neuromonitoring P value Transient RLN palsy 38 (7.7%) 19 (3.8%) 0.011 Permanent RLN palsy 12 (2.4%) 8 (1.6%) 0.368 3.9% reduction in risk of transient RLN palsy with neuromonitoring No significant difference in risk of permanent RLN palsy

Neuromonitoring and video-assisted thyroidectomy: a prospective, randomized case-control evaluation Gianlorenzo Dionigi, Luigi Boni, Francesca Rovera, Alessandro Bacuzzi, Renzo Dionigi 112 nerves-at-risk Visual Identification Alone (n = 57) Visual Identification + Neuromonitoring (n = 55) P value Transient RLN palsy 3 (8.3%) 1 (2.7%) >0.05 Permanent RLN palsy No significant difference in risks of transient and permanent RLN palsy

Evaluation of recurrent laryngeal nerve monitoring in thyroid surgery Serkan Sari, Yesim Erbil, Aziz Sumer, Orhan Agcaoglu, Adem Bayraktar, Halim Issever, Selcuk Ozarmagan 409 nerves-at-risk Visual Identification Alone (n = 199) Visual Identification + Neuromonitoring (n = 210) P value Transient RLN palsy 3 (1.5%) 3 (1.4%) >0.05 Permanent RLN palsy No significant difference in risks of transient and permanent RLN palsy

Randomized Controlled Trial of Visualization versus Neuromonitoring of the External Branch of the Superior Laryngeal Nerve during Thyroidectomy Marcin Barczynski, Aleksander Konturek, Malgorzata Stopa, Agnieszka Honowska, Wojciech Nowak 402 nerves-at-risk Visual Identification Alone (n = 202) Visual Identification + Neuromonitoring (n = 200) P value Transient RLN palsy 2 (1.0%) 1 (0.5%) 0.57 Permanent RLN palsy No significant difference in risks of transient and permanent RLN palsy

Recurrent Laryngeal Nerve Monitoring Versus Identification Alone on Post-Thyroidectomy True Vocal Fold Palsy: A Meta-Analysis Thomas S. Higgins, Reena Gupta, Amy S. Ketcham, Robert T. Sataloff, J. Trad Wadsworth, John T. Sinacori Includes 1 RCT, 8 comparative studies and 34 single-arm case series 64,699 nerves-at-risk Transient Permanent Odd Ratio: 1.07 (0.95 – 1.20) Odd Ratio: 0.99 (0.80 – 1.24) No significant difference in risks of transient and permanent RLN palsy

Neuromonitoring in thyroidectomy: a meta-analysis of effectiveness from randomized controlled trials Alvaro Sanabria, Adonis Ramirez, LuizP. Kowalski, Carl E. Silver, Ashok R. Shaha, Randall P. Owen, Carlos Suarez, Avi Khafif, Alessandra Rinaldo, Alfio Ferlito Includes 4 RCTs 2,912 nerves-at-risk Transient Permanent Risk Difference: -0.01 (-0.02 – 0.00) Risk Difference: 0.00 (-0.01 – 0.00) No significant difference in risks of transient and permanent RLN palsy

Effect of intraoperative neuromonitoring on recurrent laryngeal nerve palsy rates after thyroid surgery – A meta-analysis Shixing Zheng, Zhiwen Xu, Yuanyuan Wei, Manli Zeng, Jinnian He Includes 2 RCTs and 12 comparative studies 36,487 nerves-at-risk Transient Permanent Odd Ratio: 0.80 (0.65 – 0.99) Odd Ratio: 0.80 (0.62 – 1.03) 0.15% reduction in risk of transient RLN palsy No significant difference in risk of permanent RLN palsy

Systematic review with meta-analysis of studies comparing intraoperative neuromonitoring of recurrent laryngeal nerves versus visualization alone during thyroidectomy Adolfo Pisanu, Giulia Porceddu, Mauro Podda, Alessandro Cois, Alessandro Uccheddu Includes 3 RCTs and 17 comparative studies 35,513 nerves-at-risk Transient Permanent Odd Ratio: 0.946 (0.817 – 1.063) Odd Ratio: 0.884 (0.687 – 1.136) No significant difference in risks of transient and permanent RLN palsy

Type of study Nerves-at-risk Transient RLN palsy Permanent RLN palsy Barczynski (2009) RCT 2,000 Favours IONM ↓3.9% No difference Dionigi 112 Sari (2010) 409 (2012) 402 Higgins (2011) Meta-analysis 64,699 Sanabria (2013) 2,912 Zheng 36,487 ↓0.15% Pisanu (2014) 35,513

“High Risks” Operations Malignancies Retrosternal goiter Toxic goiter Revision surgeries Recurrent Laryngeal Nerve Monitoring Versus Identification Alone on Post-Thyroidectomy True Vocal Fold Palsy: A Meta-analysis. The Laryngoscope 2011.

Continuous Vagal Stimulation Automatic periodic stimulation from electrode placing at vagus nerve Reduction or loss of signal – RLN injury Real time feedback of RLN function Enables immediate corrective measures to prevent further injury (indirect trauma including traction, heat) Increased vagal tone, but no significant change in haemodynamics

Intermittent versus Continuous Monitoring Laryngeal neuromonitoring and neurostimulation versus neurostimulation alone in thyroid surgery: a randomized clinical trial. Head Neck 2012;34:141. 250 patients No signficant difference in incidence of RLN palsy (2.6% in intermittent stiumulation; 2.7% on continuous stimulation)

Conclusion Current literature does not support use of neuromonitoring in preventing RLN injury in thyroidectomy, comparing with visual identification of RLN ?use in “high risk” cases; definition varies between different opinions, no strong literature support

Overall incidence of RLN palsy is low Large sample size needed to show the statistical significance, if any Cost-effectiveness ~ 25 thyroidectomies with neuromonitoring costing HKD 87,500, to prevent 1 transient RLN palsy (taking 3.9% as risk reduction) Visual identification of RLN, careful nerve dissection and meticulous surgical skills – gold standard for preventing vocal cord palsy in thyroidectomy

Thank you