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

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

Importance

Use of intraoperative neuromonitoring (IONM) during thyroidectomy can nearly eliminate the risk of postoperative bilateral vocal cord palsy (VCP) by indicating staged surgery in cases of loss of signal (LOS) on the first side of planned total thyroidectomy. However, aborting planned total thyroidectomy may lead to persistence of symptoms, delay in adjuvant treatment, and patient inconvenience and distress. There are few data to guide a selective approach to total thyroidectomy in patients with first-side LOS.

Objective

To investigate outcomes of immediate bilateral surgery in patients undergoing total thyroidectomy with first-side LOS.

Design, Setting, and Participants

This cohort study was a retrospective review of outcomes for patients undergoing thyroidectomy between January 2016 and July 2023 at an academic tertiary referral center for thyroid surgery. Consecutive patients scheduled for total thyroidectomy using IONM were included. Exclusion criteria were preoperative VCP, deliberate sacrifice of recurrent laryngeal nerve (RLN), inadvertent RLN resection, and surgery performed without IONM.

Exposures

Total thyroidectomy performed using IONM.

Main Outcome Measures

Vocal mobility on first postoperative day as assessed by flexible laryngoscopy; secondary outcome measures included subjective voice assessment, other postoperative complications, and long-term vocal mobility.

Results

Among 400 patients undergoing planned total thyroidectomy (mean age, 50.5 years [range, 4-88 years]; 318 female [79.5%]), 51 (12.8%) had first-side LOS, of whom 37 (9.3%) had persistent LOS. Twenty-nine patients (56% of procedures with first-side LOS, including 18 with persistent LOS) proceeded to immediate total thyroidectomy. Postoperatively, 16 patients (55% of patients undergoing total thyroidectomy following first-side LOS, including 14 of 18 with persistent LOS) had impaired vocal mobility. One patient had bilateral VCP that did not require tracheostomy, and 2 had postoperative hypoparathyroidism. Of those whose surgery was aborted after first-side LOS, 8 of 22 (36%) underwent completion thyroidectomy at a later stage. In those undergoing completion thyroidectomy, 2 of 8 (25%) had temporary VCP after the second surgery, 2 (25%) had permanent hypoparathyroidism, and 1 (12.5%) developed inoperable cancer. Postoperative VCP was fully reversible in all but 1 patient.

Conclusion and Relevance

Among patients planned for total thyroidectomy who develop first-side LOS, immediate total thyroidectomy may be considered among those who have pressing reasons for same, and where surgical difficulties might be anticipated in a secondary surgery.

Accelerometry May be Superior to EMG for Early Evaluation of Vocal Cord Function After Nerve Injury in a Pig Model

OBJECTIVE

Vocal cord (VC) movement has been demonstrated by the use of accelerometry (ACC) to decrease in parallel with the electromyographic amplitude (EMG) during ongoing traction injury to the recurrent laryngeal nerve (RLN). When RLN function recovers, discrepancies between EMG and VC movement have been reported in clinical and experimental studies. The present study was conducted to clarify the actual relationship between EMG and VC movement measured by ACC during nerve recovery.

METHODS

EMG obtained by continuous nerve monitoring (C-IONM) was compared with ACC during traction injury to the RLN, and throughout 40-min nerve recovery. A three-axis linear accelerometer probe was attached to the VC, and ACC data were registered as described. Traction damage was applied to the RLN until there was a 70% amplitude decrease from baseline EMG, or until loss of signal (LOS), that is, EMG values ≤100 μV.

RESULTS

Thirty-two RLN from 16 immature pigs were studied. Correlation between EMG and ACC were calculated during nerve injury and nerve recovery. The mean correlations were for the 70% and LOS group from start to end of traction: 0.82 (±0.17) and 0.87 (±0.17), respectively. Corresponding correlation coefficients during 40-min recovery was 0.50 (±0.48) in the 70% group and 0.53 (±0.33) in the LOS group.

CONCLUSION

There is a high correlation between EMG and VC movement during nerve injury, and a moderate correlation during early nerve recovery. EMG recovery after RLN injury ensures sufficient VC function as assessed by ACC.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:1485-1491, 2024.

[Predictive value of strobovideolaryngoscopy, acoustic and aerodynamic measures in the prognosis of temporally unilateral vocal fold paralysis after thyroidectomy]

Objective:To investigate the strobovideolaryngoscopy, acoustic and aerodynamic characteristics of transient unilateral vocal ford paralysis（UVFP） after thyroidectomy. Methods:A retrospective analysis was made of 11 patients with temporary UVFP after thyroidectomy who were treated in Department of Otolaryngology and Head and Neck Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University from January 2013 to March 2021; 8 patients with permanent UVFP after thyroidectomy during the same period were included as a control group. The differences in baseline strobovideolaryngoscopy, acoustic and aerodynamic measures were compared between the two groups. Results:The tones of patients with temporary UVFP after thyroidectomy were all normal, and the proportions of abnormal vocal fords（vocal ford bowing, atrophy, and shortening）, ventricular adduction and glottic insufficiency were significantly lower than those of permanent UVFP patients; arytenoid cartilage stability and height mismatch of vocal ford tended to be better than permanent UVFP. The maximal phonation time（MPT） in patients with temporary UVFP was （8.5±4.1） s, which was significantly longer than （3.9±2.1） s in patients with permanent UVFP; fundamental frequency, mean airflow（MeAF） and mean subglottic pressure（SGP） were better in temporary UVFP than those in patients with permanent UVFP, but the difference did not reach statistical significance. Conclusion:None and mild glottic insufficiency, normal tone, ventricular adduction, and vocal ford appearances without vocal fold bowing, atrophy, and shortening, can be served as the predictors for the early recovery of vocal ford movement in temporary UVFP after thyroidectomy. The MPT less than 4 s, and MeAF, and SGP remarkably increased is the predictor of poor prognosis for vocal ford recovery.

Seeing Is Not Believing: Intraoperative Nerve Monitoring (IONM) in the Thyroid Surgery

Ensuring the integrity of the recurrent laryngeal nerve (RLN), the external branch of superior laryngeal nerve (EBSLN) and preservation of normal voice are the prime 'functional' goals of thyroid surgery. More in-depth knowledge of neuronal mechanisms has revealed that anatomical integrity does not always translate into functional integrity. Despite meticulous dissection, neural injuries are not always predictable or visually evident. Intraoperative nerve monitoring (IONM) is designed to aid in nerve identification and early detection of functional impairment. With the evolution of technique, intermittent monitoring has given way to continuous-IONM. Over the years, IONM gathered both support and flak. Despite numerous randomised studies, systematic reviews, and meta-analyses, there still prevails a state of clinical equipoise concerning the utility of IONM and its cost-effectiveness. This article inspects the true usefulness of IONM, elaborates on the optimal way to practice it, and presents a critical literature review.

Effectiveness of early administration of a single dose of steroids and escin after loss of signal on electromyographic signal recovery during neuromonitored thyroidectomy

BACKGROUND

The aim of this study was to evaluate the effect of a single early administration of dexamethasone and escin after loss of signal (LOS) during a neuromonitored total thyroidectomy.

METHODS

A retrospective analysis of results concerning consecutive patients undergoing total thyroidectomy was performed. Patients included in the study were divided into two groups: Group 1 for which a "wait and see" strategy was used; Group 2, receiving dexamethasone and escin immediately after LOS detection.

RESULTS

Overall 37 patients were included in Group 1 and 35 in Group 2. LOS recovery occurring in 29.7% of cases (n. 11) versus 65.7% (n. 23) respectively (p < 0.001). Postoperative fibrolayngoscopy for patients without LOS recovery showed normal cord function in 4 out of 26 cases (15.4%) in Group 1 and in 7 out of 12 (58.3%) in Group 2 (p < 0.001).

CONCLUSIONS

The early administration of dexamethasone and escin after LOS detection may achieve greater EMG signal recovery than a "wait and see" strategy.

Use of Prophylactic Steroids to Prevent Hypocalcemia and Voice Dysfunction in Patients Undergoing Thyroidectomy: A Randomized Clinical Trial

Importance

Total thyroidectomy is associated with risks related to temporary hypocalcemia and vocal quality dysfunction. Dexamethasone has been proposed to have a physiological effect on hypocalcemia and voice quality.

Objective

To assess the effect of preoperative dexamethasone used to improve hypocalcemia and postthyroidectomy voice dysfunction.

Design, Setting, and Participants

This double-blind, parallel-group, placebo-controlled randomized clinical trial was conducted from January 15, 2014, to December 31, 2019, at the Department of Surgery, Holy Family Hospital in Rawalpindi, Pakistan. All patients with a benign thyroid condition and no preoperative corrected hypocalcemia and voice or vocal quality dysfunction were included. Patients were excluded if they had previous thyroid or neck surgery, known vocal cord dysfunction on laryngoscopy, hearing or voice problems, a history of gastroesophageal reflux, stomach ulcer disease, or contraindications to steroid use.

Interventions

Corrected serum calcium levels and Voice Analog Score defined and measured preoperatively. The dexamethasone group received a 2-mL intravenous dose of 8 mg of dexamethasone 60 minutes before the induction of anesthesia. In contrast, the placebo group received 2 mL of intravenous normal saline (0.9%) 60 minutes before the induction of anesthesia.

Main Outcomes and Measures

Evidence of hypocalcemia and voice dysfunction. Voice dysfunction was defined as a subjective score of less than 50 on a Voice Analog Score scale of 0 to 100 points.

Results

A total of 192 patients (mean [SD] age, 38.9 [12.4] years; 156 women [81.2%]) were included in the study, with 96 patients randomized to each study group (dexamethasone group, mean [SD] age, 39.2 [12.1] years; 75 women [78.1%]; placebo group, mean [SD] age, 38.5 [12.9] years; 81 women [84.5%]). In the first 24 hours after undergoing thyroidectomy, 47 patients (24.4%) developed hypocalcemia and 18 (9.4%) were symptomatic. At 3 days postthyroidectomy, 4 of 96 patients (4.2%) in the placebo group had hypocalcemia compared with no patients in the dexamethasone group. At 24 hours postthyroidectomy, 8 of 96 patients (8.3%) in the dexamethasone group had voice dysfunction compared with 32 of 96 patients (33.3%) in the placebo group. A total of 40 patients (20.8%) reported voice dysfunction. The absolute reduction in the rate of hypocalcemia at 24 hours was 24% (95% CI, 11.9%-35.2%) and at 3 days was 4.2% (-0.44% to 10.0%). The rate of symptomatic hypocalcemia was 19% lower in the dexamethasone group than in the placebo group (95% CI, 11.1%-27.7%). The rate of voice dysfunction was 25% lower in the dexamethasone group than in the placebo group (95% CI, 13.7%-35.7%).

Conclusions and Relevance

In this randomized clinical trial, a single preoperative dose of dexamethasone was safe and effective in reducing postoperative hypocalcemia and voice dysfunction rates in patients undergoing thyroidectomy.

Trial Registration

ClinicalTrials.gov identifier: NCT04752852.

The use of thyroid cartilage needle electrodes in intraoperative neuromonitoring during thyroidectomy: A case-control study

BACKGROUND

The most commonly used recording-side method in intraoperative neural monitoring (IONM) detects the stimulus with the endotracheal tube surface (ETS) electrodes placed in the endotracheal tube during thyroidectomy. The thyroid cartilage needle (TCN) electrode method is an alternative recording-side system in IONM. This study compared two recording-side techniques in IONM.

METHODS

Data were retrospectively analyzed from 885 patients who underwent thyroidectomy between January 2012 and December 2020, with 110 ETS and 775 TCN electrodes. Patients' demographics, diagnosis, surgery type, and amplitudes of all stimulation steps were compared. Costs per patient were calculated.

RESULTS

No significant differences were found in the demographic data between the two groups. All amplitudes were higher in the IONM system where TCN electrodes were used than that with ETS electrodes (all stimulation steps p < 0.001, except left-V2 p = 0.007). Further, TCN electrodes were 20 times cheaper than the ETS electrodes.

CONCLUSION

TCN electrodes are an inexpensive and efficient alternative to ETS electrodes in IONM.

Value of Neurostimulation Plus Laryngeal Palpation to Predict Postoperative Vocal Fold Motility

BACKGROUND

The aim of this study was to evaluate the reliability of intraoperative neuromonitoring through recurrent laryngeal nerve stimulation and simultaneous laryngeal palpation (NSLP) in predicting postoperative vocal cord palsy and in providing useful information in the decision to perform a staged surgery in initially planned total thyroidectomy.

MATERIALS AND METHODS

A retrospective review was performed involving 552 patients for whom a total thyroidectomy was planned. In all patients, preoperative and postoperative laryngoscopy was performed. The incidence of vocal cord palsy was calculated on 1104 nerves at risk.

RESULTS

Sensitivity and specificity of NSLP were 0.9411 and 0.9925 respectively. The positive predictive value was 0.7804, the negative predictive value was 0.9981, the false positive rate was 0.8%. In 41 patients (7.4%) the initial surgical strategy was changed into a staged procedure. Nine patients (21.9%) were false positive, 32 patients (78.1%) were true positive. Finally, a two-stage thyroidectomy was performed in 27 of 41 patients.

CONCLUSIONS

High sensitivity and specificity confirm the validity of NSLP in predicting postoperative vocal cord palsy and in driving a possible staged thyroidectomy, both in benign thyroid disease and in differentiated thyroid carcinoma.

Impact of rocuronium on intraoperative neuromonitoring vagal amplitudes during thyroidectomy

PURPOSE

Neuromuscular blocking agents (NMBA) facilitate endotracheal intubation and reduce related laryngeal morbidity. However, NMBA interfere with intraoperative neuromonitoring amplitudes during thyroidectomy. The goal of this study was to evaluate the impact of rocuronium used for tracheal intubation on early intraoperative neuromonitoring vagal amplitudes observed during first thyroid lobe dissection.

METHODS

This is an observational pharmacoepidemiological study with prospective data collection and retrospective analysis. During the study period, all consecutive patients who underwent thyroid surgery with neuromonitoring were included. Patients underwent endotracheal intubation either using a single dose of rocuronium (NMBA group) or without NMBA (NMBA-free group) according to the anesthesiologist's preference.

RESULTS

Six hundred six patients were included (213 NMBA and 393 NMBA-free group patients). At V1, 39 patients (18%) in the NMBA group had an amplitude < 100 µV (need for curarization reversal in 30 patients) and 13 patients (3.3%) in the NMBA-free group (p < 0.001). In the remaining 554 patients, the mean V1 amplitude was significantly decreased in the NMBA group (544 versus 685 µV; p < 0.001). After exclusion of 25 patients with loss of signal types 1 and 2 during dissection, the difference between mean V1 and mean V2 was significantly lower in NMBA group patients (- 22 versus - 86 µV; p = 0.016).

CONCLUSION

This study provides new data showing how NMBA used for tracheal intubation significantly decrease V1 amplitude baseline and modify amplitude variations from V1 to V2 values during the first thyroid lobe dissection.

LEVEL OF EVIDENCE

Pharmacoepidemiological study.

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

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%.

An experimental study on intraoperative recovery of recurrent laryngeal nerve function

OBJECTIVE

If bilateral thyroid surgery is planned and staged thyroidectomy considered in case of loss of neuromonitoring signal (LOS), a waiting time of 20 minutes is suggested for evaluation of early nerve recovery. This recommendation is based on clinical observations and has not been thoroughly validated experimentally.

METHODS

Sixteen pigs were randomly studied, and electromyogram (EMG) was continuously recorded during traction injury until an amplitude decrease of 70% from baseline (BL) (16 nerves) or LOS (16 nerves), and further during 40-minute recovery time. At the end of the experiments, vocal cord twitch was evaluated by video-laryngoscopy.

RESULTS

In the 70% group, 8 of 16 nerves recovered to or above an amplitude of 50% of baseline after 20 minutes and finally one more after 40 minutes. In the LOS group, only one nerve showed recovery after 20 minutes and one more after 40 minutes. Video-laryngoscopy revealed good or strong vocal cord twitches, in 10 of 14 nerves in the 70% group and in only 2 of 14 nerves in the LOS group.

CONCLUSIONS

The overall intraoperative recovery was low after LOS. Even after 70% amplitude depression, only half of the nerves showed recovery to amplitudes ≥50% of BL. Nerve recovery is dynamic, and a waiting time of 20 minutes seems appropriate for the identification of early nerve recovery before decisions are taken to continue or terminate surgery. The final EMG amplitude was not always well correlated with estimated vocal cord twitch, evaluated by video-laryngoscopy. This observation needs further investigation.

Predictors and consequences of recurrent laryngeal nerve injury during open thyroidectomy: An American College of Surgeons National Surgical Quality Improvement Project database analysis

BACKGROUND

Recurrent laryngeal nerve (RLN) injury is a serious complication of thyroidectomy. The purpose of this study is to determine the predictors and consequences of RLN injury during thyroidectomy.

METHODS

A retrospective analysis was conducted using the ACS-NSQIP 2016-2017 main and thyroidectomy targeted procedure databases. Data was analyzed by multivariate logistic regression resulting in risk-adjusted odds ratios of RLN injury and morbidity/mortality.

RESULTS

Age ≥65, black race, neoplastic indication, total or subtotal thyroidectomy, concurrent neck surgery, operation time > median, hypoalbuminemia, and anemia were associated with RLN injury. Use of intraoperative nerve monitoring was associated with decreased RLN injuries. RLN injury is a risk factor for overall morbidity, hypocalcemia, hematoma, pulmonary morbidity, readmission, reoperation, and length of stay > median.

CONCLUSION

Several predictors of RLN injury during thyroidectomy are identified, while use of intraoperative nerve monitoring was associated with a decreased risk of RLN injury. RLN injury is associated increased postoperative complications.

Efficacy of Transcartilaginous Electrodes for Intraoperative Neural Monitoring During Thyroid Surgery

Objectives.

This study was conducted evaluate the efficacy of electromyography (EMG) using transcartilaginous (TC) electrodes through the thyroid cartilage and perichondrium.

Methods.

We prospectively collected EMG data from intraoperative neuromonitoring (IONM) of 54 nerves at risk in 38 patients during thyroidectomy. We followed standardized IONM procedures in all operations. EMG signals from both endotracheal tube (ET) electrodes and TC needle electrodes were recorded simultaneously. We compared the characteristics of the EMG signals and the efficacy of both methods.

Results.

Significantly higher mean EMG amplitudes were recorded by TC electrodes than by ET electrodes in all four-step procedures (V1-R1-R2-V2, P<0.001). Loss of signal (LOS) occurred in five patients in ET electrodes, but in only two patients in TC electrodes. Postoperative laryngoscopy revealed recurrent laryngeal nerve palsy in the two patients who showed LOS from both the ET and TC electrodes, and vocal cord movement was intact in the other three patients. Therefore, the positive predictive values of LOS in ET and TC electrodes were 40% and 100%, respectively.

Conclusion.

EMG recording using TC needle electrodes is feasible and effective, making it a good alternative technique for IONM.

Intraoperative nerve monitoring in thyroid surgery-shifting current paradigms

Over the past two decades, intraoperative neural monitoring (IONM) has matured into a powerful risk minimization tool. Meta-analyses of studies, most of which were limited by poor study designs and the sole use of intermittent nerve stimulation, failed to demonstrate superiority of IONM over anatomic recurrent laryngeal nerve (RLN) dissection in the absence of IONM. With the advent of continuous IONM (CIONM), intraoperative nerve electromyographic tracings, registered almost in real time during the operation, accurately predict postoperative vocal fold function when International Neural Monitoring Study Group quality standards are adhered to. CIONM aids in avoiding permanent traction-related nerve injury by urging surgeons to reverse harmful surgical maneuvers. CIONM also forms an integral part in the surgical concept of staged thyroidectomy. Delaying completion surgery on the other side until nerve function has recovered mitigates the risk of bilateral vocal fold palsy. CIONM has greatly furthered our understanding of functional RLN injury, enabling conception of effective risk minimization strategies tailored to the individual patient. The review summarizes the advances of continuous IONM technology that caused a quantum leap in risk minimization for thyroid surgery, shifting current paradigms.

Impact of continuous intraoperative vagus stimulation on intraoperative decision making in favor of or against bilateral surgery in benign goiter

The advent of continuous vagus stimulation (CVS), eliminating lag time between nerve preparation with potential trauma and stimulation, has transformed the intraoperative surgical strategy in thyroid surgery. Continuous intraoperative nerve monitoring empowers the surgeon to be optimally aware of traction-related injury to the recurrent laryngeal nerve (RLN). Electromyographic precursor lesions, called combined events, prompt surgeons to cease harmful surgical maneuvers and release the nerve before damage to the nerve is established. Complete RLN recovery, defined as restitution of the nerve amplitude to ≥50% of baseline, assures the surgeon that it is safe to pursue completion surgery of the contralateral side in one procedure. If this restitution is incomplete or absent (<50% of amplitude baseline) immediate vocal cord paralysis is likely and it is advisable to delay completion surgery until the nerve has fully recovered. This review summarizes the tremendous progress made in this dynamic field, delineating the extent to which CVS has changed the landscape: tailoring intraoperative decision making to determine the safest course of action for patients with benign goiter.