1. 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

2. 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%

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

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

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

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

7. 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

8. 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

9. Current Evidence

10. 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.

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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: (-0.02 – 0.00)
Risk Difference: 0.00 (-0.01 – 0.00)
No significant difference in risks of transient and permanent RLN palsy

17. 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

18. 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: (0.817 – 1.063)
Odd Ratio: (0.687 – 1.136)
No significant difference in risks of transient and permanent RLN palsy

19. 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

20. “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.

21. 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

22. 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)

23. 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

24. 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

25. Thank you