Correlation Between Electrophysiological Changes and Outcomes of Vocal Cord Function in 1764 Recurrent Laryngeal Nerves with Visual Integrity During Thyroidectomy

Noticeable effect of lower baseline amplitude on the predictive accuracy of intraoperative amplitude changes for postoperative vocal cord palsy: a prospective cohort study

BACKGROUND

To explore the effect of lower baseline amplitude on its predictive accuracy of postoperative vocal cord paralysis (VCP) in monitored thyroid surgery.

MATERIALS AND METHODS

Clinical and electrophysiological data were collected during thyroid surgeries performed between November and December 2021 at China-Japan Union Hospital. Univariate/multivariate regression analysis were applied to these data to examine a possible correlation. A receiver operating characteristic curve was used to evaluate predictive efficacy.

RESULTS

A total of 631 nerves-at-risk (NAR) were identified in 460 patients who were divided into two groups according to postoperative development of VCP. The VCP group included a higher percentage of NAR with V1<1000 (68.2 vs. 40.7%, respectively; P =0.014) and NAR with R1<1400 (77.3 vs. 47.0%, respectively; P =0.005) compared with the non-VCP group. Multivariate regression analysis further identified V1<1000 [odds ratio (OR)=2.688, P =0.038], R1<1400 (OR=3.484, P =0.018) as independent risk factors for postoperative temporary VCP. The receiver operating characteristic curve showed the AUC value of V signal decline for predicting VCP was 0.87. The diagnostic efficiency of R signal decline reached as high as 0.973. A multivariate logistic regression analysis identified independent risk factors for V1<1000 and these included: higher BMI (OR=1.072, P =0.013), hypertension (OR=1.816, P =0.015), smoking (OR=1.814, P =0.031), and male sex (OR=2.016, P =0.027).

CONCLUSION

In our cohort, lower baseline amplitude was an independent risk factor for developing transient postoperative VCP. It also affected the predictive efficacy of intraoperative amplitude changes on VCP. Higher BMI, hypertension, smoking, and male sex may also be closely associated with lower initial amplitude. Thus, maintaining a higher initial amplitude is critical for patient safety during thyroid surgery.

Prophylactic Central Neck Dissection Based on Preoperative Imaging and Intraoperative Surgeon's Palpation Versus Total Thyroidectomy Alone for Papillary Thyroid Cancer

INTRODUCTION

To compare the overall morbidity and recurrence of papillary thyroid cancer (PTC) after total thyroidectomy (TT) with or without prophylactic central compartment neck dissection (CCND) in cases of both preoperative and intraoperative nonsuspicious central lymph nodes (CLNs).

METHODS

A total of 570 PTC patients who harbored no preoperative and intraoperative suspicious CLNs at two institutions were enrolled. They were randomly assigned to TT alone or TT with prophylactic CCND (pCCND) after intraoperative assessment of CLNs during the surgery. Lymph nodes that were hard or large enough to be palpated were regarded as suspicious metastatic lymph nodes during the surgery. The characteristics, postoperative complications, and locoregional recurrence of the two groups were recorded and compared.

RESULTS

With a median follow-up of 5 y, the rates of lymph node recurrence in the TT alone and TT with pCCND groups were similar (7.3% versus 4.6%, P = 0.247), but there were significantly higher rates of overall morbidity (6.6% versus 19.1%, P < 0.001) when pCCND was performed.

CONCLUSIONS

pCCND is not recommended for patients with clinically node-negative PTC preoperatively and intraoperatively because of the high complication rate and lack of benefit of reducing recurrence.

Persistent subjective voice symptoms for two years after thyroidectomy

BACKGROUND

Voice change after thyroidectomy is an important issue in thyroid surgery. However, little is known about long-term voice outcomes after thyroidectomy. This study investigates the long-term voice outcomes of thyroidectomy up to two years after surgery. Also, we analyzed the pattern of recovery through acoustic tests over time.

METHODS

We reviewed data from 168 patients who underwent thyroidectomy between January 2020 and August 2020 at a single institution. The Thyroidectomy-related Voice and Symptom Questionnaire (TVSQ) score and acoustic voice analysis results were examined preoperatively and postoperative one, three, and six months, and one and two years after surgery. We divided patients into two groups based on the TVSQ score (≥15 or <15) at two years postoperatively. We investigated the difference of acoustic characteristics between the two groups and analyzed correlations between acoustic parameters and various clinical and surgical factors.

RESULTS

Voice parameters tended to recover, but some parameters and TVSQ scores exhibited deterioration two years after surgery. In the subgroups, among the many clinicopathologic factors examined, voice abuse history including professional voice users (p = 0.014), greater extent of thyroidectomy and neck dissection (p = 0.019, p = 0.029), and high pitch voice (F0; p = 0.005, SFF; p = 0.016) were associated with high TVSQ score at two years.

CONCLUSIONS

Patients frequently experience voice discomfort after thyroidectomy. After surgery, voice abuse history including professional voice users, greater extent of surgery, and higher pitch voice are associated with worse voice quality and increased risk of persistent voice symptoms over the long-term.

Is There Any Reliable Predictor of Functional Recovery Following Post-thyroidectomy Vocal Fold Paralysis?

BACKGROUND

Predicting definitive outcomes of post-thyroidectomy vocal fold paralysis (VFP) is challenging. We aimed to identify reliable predictors based on intraoperative neuromonitoring (IONM) and flexible fiberoptic laryngostroboscopy (FFL) findings.

METHODS

Among 1172 thyroid operations performed from April to December 2021, all patients who exhibited vocal fold paralysis (VFP) at post-operative laryngoscopy were included. IONM data, including type of loss of signal (LOS), were collected. Patients underwent FFL, with arytenoid motility assessment, at 15, 45 and 120 days post-operatively. Patients were divided into two groups: those who recovered vocal fold motility (VFM) by the 120th post-operative day (recovery group) and those who did not (non-recovery group).

RESULTS

Fifty-nine VFP cases (5.0% of total patients) met the inclusion criteria. Eight patients were lost at follow-up and were excluded. Overall, 9 patients were included in the non-recovery group (0.8% of total patients) and 42 in the recovery group. Among various predictive factors, only arytenoid fixation (AF) at the 15th post-operative day and Type I LOS were significant predictors for no VFM recovery (p = 0.007, RR = 9.739, CI:1.3-72.3 and p = 0.001, RR = 9.25, CI:2.2-39.3 for AF and Type I injury, respectively). The combination of type of LOS and arytenoid motility at the 15th post-op day yielded satisfactory predictive values for the progression of transient VFP to permanent.

CONCLUSIONS

Arytenoid motility at the 15th post-op day and type II LOS are associated with recovery of VFM. Type of LOS and FFL could be included in the follow-up protocols of patients with VFP to reliably predict clinical outcomes.

Total thyroidectomy versus hemithyroidectomy with intraoperative radiofrequency ablation for unilateral thyroid cancer with contralateral nodules: A propensity score matching study

Background

For unilateral papillary thyroid carcinoma (PTC) patients with contralateral benign nodules, optimal treatment decisions are made according to patient preference and the disease’s pathological features. This study was performed to evaluate the efficacy and complications of hemithyroidectomy with intraoperative radiofrequency ablation (RFA) compared with total thyroidectomy.

Methods

Patients with unilateral PTC and cytologically benign contralateral nodules were enrolled from 2014 to 2018. Total thyroidectomy or hemithyroidectomy with intraoperative RFA of the contralateral nodule was offered to patients who had anxiety regarding their disease. The operation-related parameters, transient or permanent nerve injury, hypocalcemia and disease recurrence, were recorded and compared between the two groups.

Results

After propensity score matching, 191 patients who underwent total thyroidectomy and 224 contralateral nodules in 191 patients underwent hemithyroidectomy with intraoperative RFA (HTRFA) were included. The volume reduction ratios of the contralateral nodules were 67.7% at 12 months and 95.8% at 24 months. The total thyroidectomy group reported significantly higher hypocalcemia than HTRFA within one year (7.8% vs. 2.6%, p = 0.022). Supplemental levothyroxine was not required in 28.3% (54/191) of the patients one year after HTRFA. With a median follow-up of 4.1 years, three recurrences (1.6%) were observed in the HTRFA, and no recurrence occurred in the total thyroidectomy group (p = 0.246).

Conclusions

Hemithyroidectomy for unilateral PTC and intraoperative RFA for contralateral nodules were acceptable and effective treatment approaches and did not increase the risk of complications.

Graphical Abstract

Correlation between Electrophysiological Change and Facial Function in Parotid Surgery Patients

This observational study investigated intraoperative electrophysiological changes and their correlation with postoperative facial expressions in parotidectomy patients with visual confirmation of facial nerve (FN) continuity. Maximal electromyography(EMG) amplitudes of the facial muscles corresponding to temporal, zygomatic, buccal and mandibular branches were compared before/after FN dissection, and facial function at four facial regions were evaluated before/after parotidectomy in 112 patients. Comparisons of 448 pairs of EMG signals revealed at least one signal decrease after FN dissection in 75 (67%) patients. Regional facial weakness was only found in 13 of 16 signals with >50% amplitude decreases. All facial dysfunctions completely recovered within 6 months. EMG amplitude decreases often occur after FN dissection. An amplitude decrease >50% in an FN branch is associated with a high incidence of dysfunction in the corresponding facial region. This study tries to establish a standard facial nerve monitoring (FNM) procedure and a proper facial function grading system for parotid surgery that will be useful for the future study of FNM in parotid surgery.

Analysis of voice changes after thyroidectomy using the thyroidectomy-related voice and symptom questionnaire

OBJECTIVE

After thyroidectomy, many patients suffer from voice problems and vague neck discomfort. The Thyroidectomy-related Voice and Symptom Questionnaire (TVSQ) is a self-administered questionnaire used to evaluate pre- and post-operative vocal status as well as throat and neck discomfort. We investigated voice conditions in thyroidectomy patients using the TVSQ as well as correlations between TVSQ responses and objective voice parameters. Also, we examined whether any clinicopathologic or surgical factors affect phonetic change after thyroidectomy.

METHODS

We retrospectively reviewed the records of 242 patients who underwent total thyroidectomy to treat papillary carcinoma between January to December of 2019. Of these, we enrolled 232 who exhibited normal vocal cord mobility after surgery. TVSQ responses and acoustic voice analysis results were examined preoperatively and at 1, 3, and 6 months postoperatively. We subclassified patients into favorable and unfavorable TVSQ groups based on the increase in TVSQ score (△TVSQ ≥20) at 1 month postoperatively. We then investigated the difference of acoustic characteristics between two groups and analyzed the correlations between acoustic parameters and various clinical and surgical factors including pathologic results and lymph node status by subgroup.

RESULT

All acoustic voice parameters except for the noise-to-harmonics ratio were significantly worse at 1 month postoperatively and recovered over time, but the TVSQ score did not recover from the 1-month value until 6 months postoperatively. In the subgroups, among the many clinicopathologic factors examined, advanced N stage (p = 0.002) and high positive total and central-and-lateral-neck lymph node ratios were significantly associated with an increased risk of an unfavorable TVSQ (p = 0.049, 0.027, <0.01, respectively). Among the acoustic parameters, only the changes in TVSQ total score and voice score were correlated with deterioration in jitter and shimmer at 1 month postoperatively. However, the correlations was not statistically significant and had disappeared at 6 months postoperatively.

CONCLUSION

We figured out that TVSQ was able to capture the negative effects of lymph node status and lymph node dissection on vocal outcomes after thyroidectomy. Although there was a weak correlation between worsened perturbation value and TVSQ changes, no other acoustic analysis parameters were statistically significant correlated with the TVSQ score.

Warning criterion to predict recurrent laryngeal nerve injury with percentage reduction of the amplitude of V2/R2d in neuromonitoring thyroidectomy

OBJECTIVE

To evaluate the contribution of amplitude reduction compared vagal stimulation at the end of thyroid dissection (V2) to the most distal RLN stimulation during thyroidectomy in predicting postoperative vocal cords paralysis (VCP).

METHODS

Patients with intact preoperative RLN function who underwent monitored thyroidectomy between August 2017 and April 2018 were included. We routinely tested the exposed RLN at the lowest proximal end (R2p signal) and the most distal end near the laryngeal entry point (R2d signal), and then routinely detected the vagal nerve at the horizontal plane of the inferior pole of thyroid with 2mA stimulation current. The cut-off value was calculated with Receiver Operating Characteristic curve. Rates of specificity, sensitivity, negative predictive value, positive predictive value (PPV) for V2/R2d and R2p/R2d were compared.

RESULTS

Percentage reduction of the amplitude of V2/R2d ranged from 34.8% to 76.7%. Twenty-two (1.5%) nerves developed temporary VCP, in which one nerve with VCP showed no significant amplitude reduction at the end of the surgery. There was no permanent or bilateral VCP. Sensitivity, specificity, PPV, NPV, and accuracy for the amplitude reduction of V2/R2d> 60% were 95.5%, 99.8%, 99.9%, 98.2%, respectively, for R2p/R2d were 99.5%, 99.2%, 63.6%, 99.9%, 97.7%, respectively.

CONCLUSION

Percentage reduction of the amplitude of V2/R2d is a reliable and practical warning criterion for RLN injury. When the amplitude reduction> 60% surgeons should consider the possibility of postoperative VCP and correct some surgical maneuvers.

The area under the waveform of electromyography for monitoring the external branches of the superior laryngeal nerve during thyroid surgery

Background

Injuries to the external branches of the superior laryngeal nerve (EBSLN) are difficult to identify during thyroidectomy. Monitoring the low amplitudes of the EBSLN during surgery has proven to be complicated. Therefore a new parameter, the area under the waveform (AUW), was designed to improve monitoring efficiency. The aim of this study was to determine the effectiveness of using AUW to monitor the EBSLN during thyroidectomy.

Methods

A total of 927 patients and 927 recurrent laryngeal nerves (RLN) and EBSLNs who underwent monitored unilateral thyroidectomy were included. Standardized intraoperative neuromonitoring procedures were followed. RLN injuries were confirmed using stroboscopic laryngoscopy after surgery. EBSLN injuries were identified by means of observing changes in cricothyroid muscle (CTM) twitches when stimulated. Amplitude and AUW changes were assessed using statistical analysis. The correlations between AUW and amplitude were verified using the ratio of the two parameters to determine any decreases that were observed in the number of nerve injury cases. The receiver operating characteristic (ROC) curve was used to estimate the prediction of nerve injury.

Results

The overall injury rates of the RLN and EBSLN were 3.56% and 2.05%, respectively. The AUW for the RLN and EBSLN presented linear correlations with amplitude. In the RLN injury cases, no significant difference was observed between the two parameters (P>0.05). In the cases with EBSLN injuries, the AUW decreased 64.5%±14.1%, on average, which was a greater decrease compared to that observed for amplitude 49.7%±22.2% (P<0.0001). The summary of the EBSLN injury prediction included, amplitude vs. AUW, AUC: 0.918 vs. 0.994; P<0.0001, and Youden's index: 31.54% vs. 49.58%.

Conclusions

The AUW demonstrated consistency with the change in amplitude, and the observed changes were significant. The use of the AUW allowed successful predictions for both RLN and EBSLN nerve injuries. Also, the sensitivity of AUW was greater than amplitude for predicting EBSLN injuries.

Comparison of Surgical Complications Rates Between LigaSure Small Jaw and Clamp-and-Tie Hemostatic Technique in 1,000 Neuro-Monitored Thyroidectomies

Over the past decade, the use of neuromonitoring in thyroid surgery has become well established and is increasing accepted across the world. In addition, new developments in energy devices have significantly improved efficacy in achieving hemostasis in thyroid surgery. Few studies focused on the complication rates in energy device-assisted sutureless neuro-monitored thyroidectomy. This study investigates a novel LigaSure Small Jaw (LSJ) technique for sutureless thyroidectomy and compares the surgical complication rates between LSJ and conventional clamp-and-tie technique in one thousand consecutive neuro-monitored thyroidectomy patients. Five hundred patients received sutureless thyroidectomy performed with LSJ (Group L), and 500 patients received surgery performed with conventional clamp-and-tie technique (Group C). Complication rates of postoperative hematoma, hypocalcemia and recurrent laryngeal nerve (RLN) palsy were compared between groups. The overall complication rates of hematoma, hypocalcemia (temporary/ permanent), and RLN (temporary/ permanent) palsy were 0.9%, 24.9% (24.6%/0.3%), and 1.7% (1.5%/0.2%), respectively. Group L and Group C significantly differed in postoperative hematoma rate (0.0% vs. 1.8%, respectively; p = 0.0026) and in postoperative hypocalcemia rate (20.1% vs. 30.0%, respectively; p = 0.0032). The incidence of RLN palsy did not significantly differ between Group L and Group C (1.38% vs. 2.08%; p = 0.2652). The overall surgical complication rates are low in neuro-monitored thyroidectomy. The LSJ is feasible for performing completely sutureless thyroidectomy and obtains superior outcomes of postoperative hematoma and hypocalcemia in comparison with clamp-and-tie hemostatic technique. The novel LSJ technique using double or overlapped sealing is useful for sutureless thyroidectomy. However, surgeons must carefully observe the tissue contraction that may reduce the LSJ-RLN distance and increase the risk of thermal injury during the LSJ activation.

Lymph node metastasis in suprasternal space and intra-infrahyoid strap muscle space from papillary thyroid carcinoma

Background

This study was performed to evaluate the clinicopathologic characteristics of Lymph Node metastasis between investing layer of Cervical fascia and deep fascia of infrahyoid strap Muscles (LNCM) in papillary thyroid carcinoma (PTC).

Methods

Retrospective review of patients with PTC who underwent thyroidectomy and central compartment neck dissection (CND) from January 2016 to January 2018 was performed in two tertiary referral academic medical centers. A total of 2104 consecutive patients with PTC who underwent thyroidectomy and CND were included in the retrospective review. The LNCM was resected as a separate specimen by the surgeon and the clinicopathologic characteristics of the patients were recorded. Multivariate logistic regression analysis was performed to identify risk factors for LNCM metastasis.

Results

Of 2104 PTC patients, 451 patients (21.4%) had lymph nodes in the LNCM. Among them, 68 (15.1%) cases were confirmed to be positive in the LNCM. In total, the metastasis rate of LNCM in PTC patients was 3.2% (68/2104). Univariate analysis revealed that the metastasis of LNCM were more likely to have a primary site in the inferior pole, extrathyroidal extension (ETE), central cervical metastasis, level III and level IV metastasis. Multivariate analysis further showed tumor location in the inferior pole, ETE, level III and level IV metastasis conferred a significantly increased odds ratio for LNCM metastasis.

Conclusion

Attention should be paid to the lymph tissue in the LNCM for PTC patients, especially in presence of a primary site in the inferior pole, ETE, level III and level IV metastasis.

Selective vagus-recurrent laryngeal nerve anastomosis in thyroidectomy with cancer invasion or iatrogenic transection

PURPOSE

Immediate recurrent laryngeal nerve (RLN) reconstruction at the time of thyroid cancer extirpation can provide excellent postoperative phonatory function. This study is to present our experience with the methods of RLN reconstruction, and to evaluate the role of selective vagus to RLN anastomosis (SVR) in thyroidectomy.

METHODS

Respective review of RLN reconstruction in thyroid surgery from January 2004 to October 2018 was conducted in two tertiary referral academic medical centers. Immediate RLN reconstruction was performed for primary thyroidectomy patients with intraoperative nerve tumor invasion or iatrogenic transection. Laryngofiberoscopic examination, voice evaluation of maximum phonation time, and GRBAS scale were performed preoperatively, on the second day after surgery, and monthly postoperatively for the first year.

RESULTS

A total of 37 patients were enrolled. Twenty-nine RLNs were resected caused by tumor-associated trauma; the other nerves were inadvertently transected. Direct anastomosis (DA) was performed in eight patients, free nerve graft (FNG) was performed in four patients, ansa cervicalis to RLN anastomosis (ARA) was performed in eight patients, and SVR was performed in 17 patients. The mean periods from the reinnervation surgery of DA, SVR, ARA, and FNG to the phonation recovery were 46 ± 19 (days), 41 ± 29 (days), 83 ± 21 (days), and 137 ± 32 (days), respectively. There were improvements in the GRBAS scale of perceptual voice quality at 1 month for DA and SVR, 2months for ARA.

CONCLUSIONS

Intraoperative SVR reinnervation demonstrated voice improvement postoperatively and might be an effective treatment for thyroidectomy-related permanent unilateral vocal cord paralysis.