Loss of neuromonitoring signal during bilateral thyroidectomy: no systematic change in operative strategy according to a survey of the French Association of Endocrine Surgeons (AFCE).

Lilly Khamsy,Paul E Constanthin,Samira M Sadowski,Frédéric Triponez

doi:10.1186/s12893-015-0082-5

Abstract

BackgroundTotal thyroidectomy presents a risk of bilateral vocal cord paralysis, which can lead to compromised airway. Visual Recurrent Laryngeal Nerve (RLN) identification significantly decreases this risk of RLN lesion. Yet, an anatomically intact nerve is not always functional. Intraoperative neuromonitoring (IONM) allows to test in real time the function of the RLN. In case of loss of signal (LOS) on the first operated side, some authors recommend to stop the intervention. The purpose of this study was to characterize the operative strategy of the French-speaking surgeons in case of LOS on the first side in planned bilateral thyroidectomies.MethodsAn online questionnaire was sent to the surgeons of the French Association of Endocrine Surgeons (AFCE).ResultsWe collected 69 responses (response rate: 42 %). Forty-six surgeons (66 %) used IONM. After a signal loss, 22 % (N = 10) stopped the operation in all cases, 24 % (N = 11) continued the operation in case of malignant disease and stopped in cases of benign disease, and 54 % (N = 25) continued the operation contralaterally.ConclusionsThe majority of surgeons continued the operation contralaterally as originally planned despite a loss of IONM signal at the end of the first side.

Highlights

Total thyroidectomy presents a risk of bilateral vocal cord paralysis, which can lead to compromised airway
The most feared complication following thyroid surgery is a lesion of the recurrent laryngeal nerve (RLN) [1]
Unilateral paralysis has no impact on patient survival, while paralysis of both vocal cords following a bilateral lesion of the Recurrent Laryngeal Nerve (RLN) involves their prognosis

Summary

Introduction

Total thyroidectomy presents a risk of bilateral vocal cord paralysis, which can lead to compromised airway. The presence of a muscle response to the nerve stimulation is transmitted to the surgeon by an audible and visual EMG signal on the Khamsy et al BMC Surgery (2015) 15:95 monitor, confirming the functional integrity of the RLN. A loss of signal (LOS) can be observed in various situations; when the stylus touches another structure instead of the RLN or when the patient is under myorelaxant medication, thereby preventing the contraction of the voice muscles, or when there is a lesion of RLN. Another confusing factor can be the preoperative state of the vocal cords [9]. The use of algorithms such as those described by the International Neural Monitoring Study Group reduce signal losses that do not represent nerve injuries [10]

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