Neuromonitoring of the Recurrent Laryngeal Nerve Reduces the Rate of Bilateral Vocal Cord Dysfunction in Planned Bilateral Thyroid Procedures

Abstract

Purpose: Bilateral vocal cord dysfunction (bVCD) is a rare but feared complication of thyroid surgery. This long term retrospective study determined the effect of intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) during thyroid surgeries with regard to the rate of bVCD and evaluated the frequency as well as the outcome of staged operations. Methods: Retrospective analysis of prospectively documented data (2000–2019) of a tertiary referral centers’ database. IONM started in 2000 and, since 2010, discontinuation of surgery was encouraged in planned bilateral surgeries to prevent bVCD, if non-transient loss of signal (ntLOS) occurred on the first side. Datasets of the most recent 40-month-period were assessed in detail to determine the clinical outcome of unilateral ntLOS in planned bilateral thyroid procedures. Results: Of 22,573 patients, 65 had bVCD (0.288%). The rate of bVCD decreased from 0.44 prior to 2010 to 0.09% after 2010 (p < 0.001, Chi2). Case reviews of the most recent 40 months period identified ntLOS in 113/3115 patients (3.6%, 2.2% NAR), of which 40 ntLOS were recorded during a planned bilateral procedure (n = 952, 2.1% NAR). Of 21 ntLOS occurring on the first side of the bilateral procedure, 15 procedures were stopped, subtotal contralateral resections were performed, and thyroidectomy was continued in 3 patients respectively, with the use of continuous vagal IONM. Eighteen cases of VCD were documented postop, and all but one patient had a full recovery. Seven patients had staged resections after 1 to 18 months (median 4) after the first procedure. Conclusion: IONM facilitates reduced postoperative bVCD rates. IONM is, therefore, recommendable in planned bilateral procedures. The rate of non-complete bilateral surgery after intraoperative non-transient LOS was 2%.

Outcomes of Immediate Total Thyroidectomy in First-Side Loss of Neuromonitoring Signal

“…One further patient ended up having an aggressive thyroid cancer after abortion of planned total thyroidectomy. Other authors did not report or reported limited information regarding complications among completion thyroidectomy cases . However, the number of cases undergoing completion thyroidectomy in this study is very low, so caution should be exercised drawing any conclusions.…”

“…While IONM can offer the significant benefit of nearly eliminating the risk of bilateral VCP after thyroidectomy by prompting the surgeon to abort the operation in case of first-side LOS, [12][13][14] this approach may lead to failure to resolve symptoms, delay in treatment, and patient dissatisfaction due to need for a secondary procedure. There are also risks of morbidity from the second procedure, which may be increased due to scarring from the first operation.…”

“…11 One incontrovertible benefit of IONM is the ability to nearly completely eliminate bilateral VCP by prompting the surgeon to abort second-side surgery in patients with loss of signal (LOS) on the first side. [12][13][14] In such cases, patients requiring total thyroidectomy may undergo staged completion thyroidectomy after documentation of return of first-side vocal mobility. 13,14 The downside of aborting planned total thyroidectomy after first-side LOS is that it incurs the need for a second operation for many patients, which may lead to prolongation of symptoms in patients with compressive goiters and hyperthyroidism; delay in adjuvant treatment in patients with thyroid cancer; and patient inconvenience, anxiety, and dissatisfaction.…”

“…[12][13][14] In such cases, patients requiring total thyroidectomy may undergo staged completion thyroidectomy after documentation of return of first-side vocal mobility. 13,14 The downside of aborting planned total thyroidectomy after first-side LOS is that it incurs the need for a second operation for many patients, which may lead to prolongation of symptoms in patients with compressive goiters and hyperthyroidism; delay in adjuvant treatment in patients with thyroid cancer; and patient inconvenience, anxiety, and dissatisfaction. In addition, revision thyroid surgery may be more difficult due to scarring from the first operation, with consequent increased risk of surgical morbidity.…”

Editorial on the Special Issue “Novel Methods of Diagnostics of Thyroid and Parathyroid Lesions”

“…In another paper, the advantages of the application of intraoperative neuromonitoring of the recurrent laryngeal nerve (IONM) were shown, which, according to authors' findings, reduces the rate of one of the most important complications of thyroid surgeries in bilateral planned thyroidectomies -bilateral vocal cord dysfunction (bVCD) [21]. This retrospective analysis involved prospectively documented data from 20-year experience of a tertiary referral center.…”