Contralateral surgery in patients scheduled for total thyroidectomy with initial loss or absence of signal during neural monitoring

Abstract

Background: Staged total thyroidectomy has been advised to prevent bilateral recurrent laryngeal nerve paralysis when loss of the signal from neural monitoring is observed after dissection of the initial thyroid lobe. This is supported by expert opinion but hard evidence is lacking. A lost signal can return during surgery or, even if it persists, its positive predictive value is only in the range 60-70 per cent. The aim of the present study was to investigate the clinical outcome of patients in whom total thyroidectomy was performed following loss of signal after dissection of the first thyroid lobe. Methods:This was a prospective observational study of adult patients scheduled for neural monitoring during total thyroidectomy. The prevalence of first-side absence or loss of signal was recorded. The contralateral thyroid lobe was approached routinely. The vagus and recurrent laryngeal nerves on the first side were retested during and at the end of the contralateral procedure.Results: Some 462 patients were included. Loss (32 patients) or initial absence (8) of signal at dissection of the first thyroid lobe was noted in 40 patients (8⋅7 per cent). Total thyroidectomy was completed in 29 patients, and a change of surgical strategy adopted in 11 patients with benign disease. At retesting, 15 of 37 initially silent nerves recovered electromyographic signal after a mean(s.d.) interval of 30(14) min. Postoperative vocal cord palsy/paresis was demonstrated in 24 of 40 patients. One patient developed a bilateral paresis that could be managed conservatively. Conclusion:After an absence or loss of signal of the recurrent laryngeal nerve following dissection of the first thyroid lobe, contralateral thyroidectomy can be performed safely, avoiding the expense, psychological burden and potential complications of a second procedure.

An experimental study on intraoperative recovery of recurrent laryngeal nerve function

“…recovered after LOS to an amplitude above 100 μV. 19 In our experimental study, we observed incomplete recovery after LOS in 13 of 16 nerves (81%) after the suggested 20-minute waiting time. The higher rate of incomplete recovery in our experimental setup, than described in clinical observational studies, may be explained by the standardized injury mechanism using only traction.…”

Efficacy of Transcartilaginous Electrodes for Intraoperative Neural Monitoring During Thyroid Surgery

“…Higher EMG amplitudes make it possible to monitor RLN function more sensitively. Thus, surgeons can obtain feedback from IONM, change their procedures, and be more careful when performing procedures near the RLN [37][38][39].…”

“…However, several factors can influence the EMG signal, resulting in false positive or negative results. This can make decisions difficult, such as when LOS occurs on one side during a contralateral operation [38,39]. Therefore, it is very important to know whether the LOS is a true signal.…”

Author response to: Comment on: Contralateral surgery in patients scheduled for total thyroidectomy with initial loss or absence of signal during neural monitoring

“…Thanks to Piccin et al . for their comment on our article on avoiding staged thyroidectomy in cases of initial signal loss. The authors, however, do not discuss our data or our reasoning, they merely give their opinion.…”