Injury of the external branch of the superior laryngeal nerve in thyroid surgery

Comparison of diffusion ranges at different local anesthetic volumes during superior laryngeal nerve block

OBJECTIVES

Ultrasound-guided superior laryngeal nerve (SLN) block is a practical and painless approach to avoid the hemodynamic stress response during endotracheal intubation and relieve sore throat after laryngeal surgery. The main purpose of this study was to establish an optimal dosage of local anesthetic when performing SLN block to help anesthetists balance analgesia and side effects.

METHODS

Twenty fresh larynx specimens were obtained immediately after resection and then injected with 2-, 3-, 4-, or 5- mL of a lidocaine-blue dye mixture at bilateral SLN puncture sites. Superficial areas of deposited blue dye were measured. Dye leakage and surrounding dyed tissue were recorded. Another 40 patients were included in the ultrasound investigation. Distances between the internal branch of the SLN (iSLN) and adjacent structures were calculated.

RESULTS

The dye spread area was greater with the administration of larger doses, especially to the visceral space. A 2- or 3-mL injection of local anesthetic was sufficient to infiltrate the SLN gap. A higher incidence of dye leaking out of the thyrohyoid membrane and anterior epiglottis space was observed; furthermore, there was substantially more dyed hyoid/thyroid cartilage with 4 and 5 mL of injected dye mixture than 2 mL. There was no significant difference between the specimen and ultrasound measurements of for length of iSLN-adjacent structures.

CONCLUSIONS

In the Chinese population, 2- or 3- mL of local anesthetic is a safe dose during SLN block. A larger volume could overflow from the cavity to cause complications. The thyrohyoid membrane combined with the superior laryngeal artery is a reliable target for positioning the iSLN during ultrasound-guided regional anesthesia.

Step-by-Step Thyroidectomy-Incision, Nerve Identification, Parathyroid Preservation, and Gland Removal

Thyroidectomy is a surgical procedure to remove part or all of the thyroid gland. Although the general tenets of surgery have remained the same, improvements in techniques, diagnostics, understanding of anatomy, and technology have allowed thyroid surgery to become a standard, effective, and safe surgery. For surgeons undertaking this procedure, it is imperative to have an in-depth knowledge of critical anatomy and a comprehensive understanding of surgical techniques to perform safe and effective surgery. This article aims to provide an overview of surgical techniques that may be applied in both benign and malignant disease settings.

Prevalence and risk factors for dysphagia in older adults after thyroid and parathyroid surgery

BACKGROUND

We aimed to determine the prevalence and risk factors for dysphagia in adults 65 years and older before and after thyroidectomy or parathyroidectomy.

METHODS

We performed a longitudinal prospective cohort study of older adults undergoing initial thyroidectomy or parathyroidectomy. We administered the Dysphagia Handicap Index questionnaire preoperatively and 1, 3, and 6 months postoperatively. We compared preoperative and postoperative total and domain-specific scores using paired t tests and identified risk factors for worse postoperative scores using multivariable logistic regression.

RESULTS

Of the 175 patients evaluated, the mean age was 71.1 years (range = 65-94), 73.7% were female, 40.6% underwent thyroidectomy, 57% underwent bilateral procedures, and 21.1% had malignant diagnoses. Preoperative swallowing dysfunction was reported by 77.7%, with the prevalence 22.4% greater in frail than robust patients (P = .013). Compared to preoperative scores, 43.4% and 49.1% had worse scores at 3 and 6 months postoperatively. Mean functional domain scores increased by 62.3% at 3 months postoperatively (P = .007). Preoperative swallowing dysfunction was associated with a 3.07-fold increased likelihood of worse functional scores at 3 months. Whereas frailty was associated with preoperative dysphagia, there was no association between worse postoperative score and age, sex, race, frailty, body mass index, smoking status, gastroesophageal reflux disease, comorbidity index, malignancy, surgical extent, or type of surgery.

CONCLUSION

Adults 65 years and older commonly report swallowing impairment preoperatively, which is associated with a 3.07-fold increased likelihood of worsened dysphagia after thyroid and parathyroid surgery that may persist up to 6 months postoperatively.

Intraoperative cricothyroid muscle electromyography may contribute to the monitorization of the external branch of the superior laryngeal nerve during thyroidectomy

Background

In thyroid surgery, both the recurrent laryngeal nerve (RLN) and external branch of the superior laryngeal nerve (EBSLN) should be preserved for maintaining the vocal cord functions. We aimed to evaluate whether EMG of the CTM applied after the superior pole dissection provided additional informative data to the IONM via ETT or not, regarding the EBSLN function.

Methods

The prospectively collected data of the patients, who have undergone thyroidectomy with the use of IONM for the exploration of both the RLN and EBSLN between October 2016 and March 2017, were evaluated retrospectively. Patients over 18 years of age with primary thyroid surgery for malignant or benign thyroid disease, and whom were applied CTM EMG with a needle electrode after the completion of thyroidectomy were included in the study. In the study, each neck side was evaluated as a separate entity considering the EBSLN at risk.

Results

The data of 41 patients (32 female, 9 male) (mean age, 46.7 + 9.1; range, 22-71) were evaluated. Sixty seven EBSLNs out of 26 bilateral and 15 unilateral interventions were evaluated. With EBSLN stimulation after the superior pole dissection, positive glottic EMG waveforms via ETT were obtained in 45 (67.2%) out of 67, and the mean glottic amplitude value was 261 + 191 μV (min-max: 116-1086 μV). Positive EMG responses via the CTM EMG were achieved from all of the 67 EBSLNs (100%) with stimulation using a monopolar probe at the most cranial portion above the area of divided superior pole vessels. The mean value of CTM amplitudes via CTM EMG obtained with EBSLN stimulation was 5268 + 3916 μV (min-max:1215 -19726 μV). With EBSLN stimulation, the mean CTM EMG amplitude was detected significantly higher than the mean vocal cord amplitude (p<0.0001). The CTM EMG provided more objective quantifiable data regarding the EBSLN function (100% vs 67,2%, p<0.001).

Conclusion

In addition to the IONM via ETT, intraoperative post-dissection CTM EMG via needle electrode is a safe, simple and applicable method that may provide significant additional informative data to IONM with ETT by obtaining and recording objective quantitative data related to the EBSLN function.

Analysis of Voice Quality After Thyroid Surgery

OBJECTIVES

Voice changes are a common complication after a thyroidectomy, which is a surgical procedure involving partial or total removal of the thyroid gland. The main objective of this work is to examine the possible voice disorders after thyroid surgery. More precisely, it is an investigation of partial and total thyroidectomy, as well as the effects that cancerous and noncancerous thyroid glands can have regarding postsurgical vocal and their association with age and gender.

METHODS

Patients were evaluated using acoustic voice parameters, including harmonics-to-noise ratio (HNR), fundamental frequency (F0), jitter, speaker phonation frequency (SPF) range, cepstral peak prominence (CPP), maximum phonational frequency range (MPFR), and shimmer at the preoperative stage and postoperatively at the 1 day, and first-month stages.

RESULTS

Results demonstrated a significant change in F0 parameters, SPF range, and CPP feature 1 month after surgery, depending on the type of thyroidectomy and thyroid pathology. No significant changes were observed in the HNR, shimmer, and jitter features. Age was associated with the CPP parameter in the entire sample. In contrast, the MPFR parameter was also related to the type of thyroidectomy in the entire sample. However, maximum F0 was significantly associated with the type of thyroidectomy, specifically in the female sample.

CONCLUSIONS

Results indicated that a thyroidectomy can have a negative impact on voice quality. The age and type of thyroidectomy performed are not responsible for this change. Potentially this change can be due to factors such as nerve damage or the subjects' experience, such as job, anxiety, and their physical condition, as well as treatments they may have undergone before thyroidectomy. Further efforts are needed to fully understand the background of voice changes after thyroidectomy.

Revisiting Loré's retrograde thyroidectomy from the perspective of preserving the external branch of the superior laryngeal nerve

Background

Injury to the external branches of the superior laryngeal nerve (EBSLN) is the main reported cause of inexplicable post-thyroidectomy dysphonia (PTD) without recurrent laryngeal nerve (RLN) injury. Loré proposed a retrograde thyroidectomy (RT) technique in which the superior pole is dissected as a final step after the Berry ligament division, making this approach advantageous for protecting the EBSLN. However, evidence of this protective effect remains insufficient. We aimed to evaluate EBSLN function following RT and conventional thyroidectomy (CT) using postoperative electromyography (EMG).

Methods

This is a retrospective cohort study conducted at a single tertiary center. Consecutive patients who had undergone CT or RT were included. Bilateral EMG of the cricothyroid muscle was performed 2-3 months postoperatively in all patients. Patient characteristics, postoperative findings of bleeding events, drain amount, hypocalcemia, calcium replacement, RLN function, and EBSLN function were thoroughly reviewed and compared between the two surgical approaches. Abnormalities in the EMG findings were reported based on the wave configuration, and the results were graded into four categories.

Results

Seven hundred and thirty-one consecutive patients who underwent CT (n=341), or RT (n=390) were included, and a total of 1,179 RLNs and EBSLNs were at risk in CT (n=601) and RT (n=578). The CT and RT groups had similar clinical characteristics and surgical data. Two groups presented similar postoperative results for bleeding incidence, drain amount, and hypocalcemia. All RLNs were identified in both groups and their permanent function was preserved. EBSLN was significantly less frequently identified in the surgical field during RT than it was during CT (0.3% vs. 4.2%, respectively; P<0.001). Abnormal rates of postoperative EMG on the EBSLN were significantly lower in the RT group than in the CT group (1.7% vs. 7.8%, respectively; P<0.001), while the CT group presented with a higher grade of abnormal EMG (P<0.001).

Conclusions

The RT technique may be beneficial for preserving EBSLN function. Meticulous capsular dissection and appropriate traction of the upper pole facilitated by RT are crucial for decreasing the risk of EBSLN injury, which can be achieved without directly identifying the nerve.

Utility of video-assisted method for identifying and preserving the external branch of the superior laryngeal nerve during thyroidectomy

Background

The EBSLN is vulnerable to damage during thyroidectomy, results in voice related complications, negatively affect patient quality of life, routine identification of the EBSLN prior to surgical manipulation is necessary for a complication-free thyroidectomy. We aimed to validate a video-assisted procedure for identifying and preserving the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy and analyze the EBSLN Cernea classification and the localization of the nerve entry point (NEP) from the insertion of the sternothyroid muscle.

Methods

A prospective descriptive study was performed; 134 patients, who scheduled for lobectomy with an intraglandular tumor max diameter ≤ 4 cm and without extrathyroidal extension, were randomly divided into the video-assisted surgery (VAS) and conventional open surgery (COS) groups. We used the video-assisted surgical procedure for visually identifying the EBSLN directly, and compared the differences in the visual identification rate and total identification rate of the two groups. We also measured the localization of the NEP using the insertion of the sternothyroid muscle as a reference.

Results

There was no statistically significant difference in clinical characteristics between the two groups. The visual identification rate and total identification rate were significantly higher in the VAS group than the COS group (91.04% vs. 77.61%, 100% vs. 89.6%). The EBSLN injury rate was 0 in both groups. The mean vertical distance (VD) of the NEP from the sternal thyroid insertion was 1.18 mm (SD 1.12 mm, range, 0-5 mm), with approximately 88.97% of the results occurring within the 0-2 mm range. The mean horizontal distance (HD) was 9.33 mm (SD 5.03 mm, range, 0-30 mm), with over 92.13% of the results occurring within the 5-15 mm range.

Conclusion

Both the visual and total identification rates of the EBSLN were significantly higher in the VAS group. This method provided a good visual exposure rate of the EBSLN, aiding in identifying and protecting the EBSLN during thyroidectomy.

Comparison of the endoscopic thyroidectomy via areola approach and open thyroidectomy: A propensity score matched cohort study of 302 patients in the treatment of papillary thyroid non-microcarcinoma

Background

The endoscopic thyroidectomy via areola approach (ETAA) is widely used in patients with benign thyroid tumors and papillary thyroid microcarcinoma (PTMC). Its safety and complication rates are reported to be similar to open thyroidectomy (OT). This study aimed to evaluate the safety and feasibility of ETAA, compared with OT, in patients with papillary thyroid non-microcarcinoma (PTNMC).

Methods

We retrospectively reviewed all patients with PTNMC who underwent ETAA or OT in our hospital from January 2017 to December 2021. A total of 302 patients were matched at a ratio of 1:1 by the propensity score matching (PSM) analysis and surgical outcomes. Safety and feasibility were analyzed between two groups.

Results

Before PSM, patients in the ETAA group were younger (p < 0.001) and had a larger proportion of female patients (p < 0.001) with a lower BMI (p < 0.001) compared with the OT group. The ETAA group also had a higher proportion of unilateral thyroidectomy (p = 0.002). PSM was used to create a highly comparable control group. After PSM, the ETAA group had a longer operative time (p < 0.001), larger blood loss (p = 0.046) and total drainage amount (p = 0.035), with higher C-reactive protein (p = 0.023) and better cosmetic outcomes (p < 0.001). There were no significant differences in the following clinicopathologic characteristics: number of dissected positive lymph nodes, rate of recurrent laryngeal nerve signal weakened, parathyroid autotransplantation, postoperative pain, hospital stay, complications, and oncologic completeness. There was no patient converted to OT in the ETAA group and two patients suffered from persistence/recurrence in the follow-up.

Conclusion

ETAA is a safe and feasible surgical approach for patients with PTNMC.

Effect of mouse nerve growth factor combined with the exposure of the external branch of superior laryngeal nerve on voice changes after thyroidectomy: a prospective non-randomized controlled trial

Background

The superior laryngeal nerve (SLN) injury may also affect vocal fold function and voice quality. It is efficient yet simple approach to expose the external branch of the superior laryngeal nerve (EBSLN). Neurotrophic agent mouse nerve growth factor (mNGF) to treat patients after thyroid surgery, and found it had significant efficacy in improving the voice of patients. However, the potential effectiveness and safety of mNGF combined with EBSLN were unclear.

Methods

In this study, 96 patients who suffered from hoarseness after thyroidectomy at Hangzhou First People's Hospital between January 2018 and October 2019 were screened and divided into the control group and the observation group by patients' choice. In the control group, the SLN was not exposed. In the observation group, the SLN was exposed. The mNGF treatment was administered for observation group once a day at 20 µg each time for 4 weeks. The data of acoustic voice indicators was analysis by univariate analyses. Patients in both groups were followed up for more than 6 months. The rate of SLN damage was compared between two groups.

Results

The baseline clinical characteristics of the two groups showed no statistic difference. The results showed that the fundamental frequency was significantly lower 1 month after surgery than 3 days after surgery in both groups. The fundamental frequency perturbation, shimmer, maximum phonation time, highest fundamental frequency, and dysphonia severity index in 1 month after surgery were significantly higher than they were 3 days after surgery (all P<0.001). There was no significant difference in the postoperative harmonic-to-noise ratio between the 2 groups (P=0.426).

Conclusions

MNGF combined with the exposure and protection of the EBSLN effectively may prevent voice damage after thyroid surgery.

Papillary thyroid carcinoma with rare lymph node metastasis between the non-ipsilateral sternocleidomastoid and striate muscles: two case reports and literature review

Background

Differentiated thyroid cancer (DTC) has a high incidence but a generally good prognosis. However, lymph node metastasis is likely to occur. It usually metastasizes from the central group lymph nodes to the deep cervical lymph nodes and less frequently to the sternocleidomastoid-sternohyoid muscle. The lymph nodes between the sternocleidomastoid and sternohyoid muscles (LNSS) is easily overlook. Ignoring the preoperative assessment and dissection of level LNSS, especially in the contralateral neck level LNSS, may lead to incomplete surgery and thus require reoperation. The metastatic relevant factors and pathway for LNSS remains inconclusive require further investigation. There is a lack of reports of contralateral or bilateral cervical level LNSS metastasis in thyroid cancer. We hope to arouse attention to the level LNSS through our two case reports.

Case Description

We report two cases of non-ipsilateral LNSS metastases. The patients were diagnosed with thyroid cancer by fine-needle aspiration (FNA), and ultrasound examination showed enlarged lymph nodes at the LNSS level. After surgical treatment and postoperative paraffin pathology, both patients were diagnosed with papillary thyroid carcinoma (PTC) and LNSS-level lymph node metastasis. Case 1 was a 63-year-old woman admitted to our hospital with a 15-day history of an untreated thyroid nodule and preoperative euthyroidism. This patient underwent total thyroidectomy, central and left neck LNSS dissection. Her prognosis was good, and there were no signs of recurrence at her 6-month follow-up appointment; Case 2 was a 24-year-old woman admitted to our hospital for a physical examination of an anterior cervical mass that had been present for 1 year and preoperative euthyroidism. This patient underwent total thyroidectomy, central and bilateral neck LNSS dissection. Her prognosis was good, and there were no signs of recurrence at her 12-month follow-up appointment.

Conclusions

The occurrence of contralateral and bilateral simultaneous LNSS metastasis in thyroid cancer is relatively rare. However, in clinical practice, surgeons should focus on the evaluation and clearance of LNSS, especially in patients with cancer foci located in the lower pole, cancer foci invading the anterior cervical band muscle, extensive metastasis in the lateral cervical lymph nodes or stages T3/4 and to reduce postoperative recurrence.

2022 European Thyroid Association Guideline for the management of pediatric Graves' disease

Hyperthyroidism caused by Graves' disease (GD) is a relatively rare disease in children. Treatment options are the same as in adults - antithyroid drugs (ATD), radioactive iodine (RAI) or thyroid surgery, but the risks and benefits of each modality are different. The European Thyroid Association guideline provides new recommendations for the management of pediatric GD with and without orbitopathy. Clinicians should be alert that GD may present with behavioral changes or declining academic performance in children. Measurement of serum TSH receptor antibodies is recommended for all pediatric patients with hyperthyroidism. Management recommendations include the first-line use of a prolonged course of methimazole/carbimazole ATD treatment (3 years or more), a preference for dose titration instead of block and replace ATD, and to avoid propylthiouracil use. Where definitive treatment is required either total thyroidectomy or RAI is recommended, aiming for complete thyroid ablation with a personalized RAI activity. We recommend avoiding RAI in children under 10 years of age but favor surgery in patients with large goiter. Pediatric endocrinologists should be involved in all cases.

Transcutaneous Laryngeal Ultrasound for Vocal Cord Paralysis Assessment in Patients Undergoing Thyroid and Parathyroid Surgery-A Systematic Review and Meta-Analysis

Recurrent laryngeal nerve injury is an important complication following thyroid and parathyroid surgery. Recently, Transcutaneous laryngeal ultrasound (TLUSG) has emerged as a non-invasive alternative to laryngoscopic examination for vocal cord (VC) assessment. The aim of the systematic review and meta-analysis was to determine its diagnostic accuracy in reference to laryngoscopy. It was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. MEDLINE, Scopus, Cochrane library and Web of Science databases were searched to identify relevant articles. Sixteen studies were included in the review. Pooled diagnostic accuracy was calculated based on weighted arithmetic mean and plotting forest plot. The pooled visualization rate was 86.28% and 94.13% preoperatively and postoperatively, respectively. The respective pooled sensitivity and specificity was 78.48% and 98.28%, and 83.96% (CI 95%: 77.24-88.50%) and 96.15% (CI 95%: 95.24-96.88%). The diagnostic accuracy improved if transverse and lateral approaches, and valsalva maneuver were utilized. Male gender and older age were the most crucial risk factors for VC non-visualization. TLUSG is an efficacious screening tool for vocal cord palsy due to its high sensitivity. It is likely to prevent unnecessary laryngoscopic examination in around 80% of patients, with the potential for becoming a gold standard for specific (female/young) patient cohort through assimilative modifications use, increasing expertise and development of objective measurements in the future.

Post-thyroidectomy complications in southwestern Saudi Arabia: a retrospective study of a 6-year period

BACKGROUND

Thyroidectomy is the surgical removal of all or part of the thyroid gland for non-neoplastic and neoplastic thyroid diseases. Major postoperative complications of thyroidectomy, including recurrent laryngeal nerve injury, hypocalcemia, and hypothyroidism, are not infrequent.

OBJECTIVE

Summarize the frequency of surgical complications of thyroidectomy.

DESIGN

Retrospective.

SETTING

Secondary health facility in southwestern Saudi Arabia.

PATIENTS AND METHODS

We collected data from the records of patients who were managed for thyroid diseases between December 2013 and December 2019.

MAIN OUTCOME MEASURE

Complications following thyroidectomy.

SAMPLE SIZE

339 patients, 280 (82.6%) females and 59 (17.4%) males.

RESULTS

We found 311 (91.7%) benign and 28 (8.3%) malignant thyroid disorders. Definitive management included 129 (38.1%) total thyroidectomies, 70 (20.6%) hemithyroidectomies, 10 (2.9%) subtotal thyroidectomies and 5 (1.5%) near-total thyroidectomies with 125 (36.9%) patients treated non-surgically. The overall complication rate was 11.3%. There were 4 (1.9%) patients with recurrent laryngeal nerve palsy, 16 (7.5%) patients with temporary hypoparathyroidism, 1 (0.5%) patient with paralysis of the external branch of the superior laryngeal nerve and 3 (1.4%) patients with wound hematoma.

CONCLUSION

The rate of complications following thyroidectomy is still high. There is a need for emphasis on comprehensive measures to control the high rate of complications.

LIMITATIONS

Retrospective design and no long-term follow up to monitor late complications.

CONFLICT OF INTEREST

None.

The Superior Laryngeal Nerve and Its Vulnerability in Surgeries of the Neck

Anatomical considerations of the superior laryngeal nerve (SLN), a branch of the vagus, provides information to minimize the potential for iatrogenic intraoperative injury, thereby preventing motor and sensory dysfunctions of the larynx. The present study aims to assess the variation of the SLN and its relationship to the superior thyroid artery (STA) and superior laryngeal artery (SLA). The study was done on 35 formalin-fixed cadavers at Oakland University in 2018-2019. In our study, we found that out of 21 cadavers, 52.4% of the external laryngeal branches (ebSLN) are related posteromedial to the STA, while 47.6% are related anteromedial to it. Out of 14 cadavers, 64.3% of the internal laryngeal branches (ibSLN) are related superoposterior to the SLA, while 35.7% are inferoposterior to it. In most cases, the SLA crosses above the ebSLN while traveling to pierce the thyrohyoid membrane to reach the larynx. The data demonstrate that both the ebSLN and ibSLN display variation in their relationship with the STA and the SLA, respectively. Awareness of these variable relationships is critical for identification and isolation of these structures in order to prevent consequences of nerve injury, primarily a reduction in the highest attainable frequency of the voice and aspiration pneumonia.

Narrative review of management of thyroid surgery complications

Currently, thyroid surgery is the most common and safe operation worldwide. However, thyroidectomy is still not free from the risks of complications and death due to the anatomical structure and physiological function particularity of the thyroid gland. Postoperative complications affect the life quality and life safety of patients after surgery. The common complications include hypoparathyroidism (HP), recurrent laryngeal nerve (RLN) injury, injury to the external branch of the superior laryngeal nerve (EBSLN), postoperative bleeding (PB), thoracic duct injury, laryngeal edema, tracheospasm, tracheal injury, and esophageal injury. A severe complication, such as dyspnea, asphyxia, or thyroid crisis, might cause the death of the patient. Therefore, every thyroid surgeon's responsibility is to remain alert and aware of the occurrence of various intraoperative and postoperative complications and exercise effective prevention and treatment. This is closely related to the advancement in thyroid disease research, the increase in local anatomy knowledge, the standardization of surgical approaches, the improvement in operating skills, the application of new technologies, and the emphasis on specialty training. In addition, many complications that effect patients are much better tolerated if the patient has appropriate expectations of what the complications are and how to treat them. Open communication between surgeon and patient optimizes the potential negative effects that complications may have on patients' quality of life. This paper discusses the prevention, recognition and therapy of intraoperative and postoperative complications in thyroid surgery.

Unmapped landmarks around branches of the Superior Laryngeal Nerve: An exploratory cadaveric study

Objectives

Preserving the External Branch of Superior Laryngeal Nerve (EBSLN) and Internal Branch of Superior Laryngeal Nerve (IBSLN) is essential during thyroidectomy. However, due to potential distortions caused by large goitres, the present anatomical landmarks used to identify these nerves are flawed. Although under such circumstances, bony landmarks may offer more stable reference points, not much has been explored in this regard. This study measures the distance between the most vulnerable points of the EBSLN and IBSLN and their relatively unexplored bony landmarks, such as the hyoid bone and thyroid notch as well as soft-tissue landmarks like the origin of the Superior Thyroid Artery (STA) and carotid bifurcation.

Methods

An exploratory cadaveric study was conducted in a medical school affiliated with a tertiary care hospital. The detailed analysis included 13 sides from 8 cadavers.

Results

The average distance from the EBSLN piercing site to the greater cornua of the hyoid bone, thyroid cartilage prominence, origin of the STA, and carotid bifurcation was 35.1(±7.2) mm, 33.3(±3.8) mm, 25.7(±6.3) mm, and 31.5(±5.0) mm, respectively and from the IBSLN piercing site was 15.9(±5.9) mm, 32.9(±4.7) mm, 16.3(±4.2) mm, and 20.7(±5.9) mm, respectively. For most cadavers, the distal EBSLN had Cernea type 2a-like relationship with the STA. Certain variations were also observed in the way these nerves branched with respect to the origin of the STA.

Conclusions

This study provides metric information (linear measurements) regarding the distance between the branches of SLN and certain unique landmarks. This could potentially aid in minimising intraoperative trauma to these branches.

Superior Laryngeal Nerve Signal Attenuation Influences Voice Outcomes in Thyroid Surgery

OBJECTIVES/HYPOTHESIS

The objective was to identify whether injury of the external branch of the superior laryngeal nerve (EBSLN) or changes in EBSLN parameters after dissection during thyroidectomies correlate with changes in voice quality postoperatively.

STUDY DESIGN

Prospective multicenter case series.

METHODS

A prospective multicenter study was conducted on patients undergoing thyroidectomies with intraoperative nerve monitoring. Electromyography waveforms of EBSLN stimulation before (S1) and after superior pole dissection (S2) were evaluated using endotracheal tube (ETT) and cricothyroid intramuscular (CTM) electrodes. Voice outcomes were assessed using Voice-Related Quality of Life Surveys and Voice Handicap Index.

RESULTS

A total of 131 at-risk EBSLNs were evaluated in 80 patients. Two nerves showed loss of CTM twitch coupled with an absent S2 signal response. Complete EBSLN loss of signal was more likely with: 1) Cernea EBSLN anatomic classification Type 2B; 2) with a longer distance from the sternothyroid muscle insertion site; and 3) with larger lobar volumes (P < .05). Patients who experienced a more than 50% decrement in CTM amplitudes of S2 (n = 7) by CTM electrodes had a statistically significant decline in their voice outcomes compared to those who did not (n = 69) (P < .05).

CONCLUSIONS

Patients experienced worse voice outcomes when at least one EBSLN response amplitude decreased by more than 50% after dissection when measured by CTM needle electrodes. CTM needle electrodes have an ability to measure finer amplitude changes compared to ETT electrodes, may represent a safe method to deduce subtle EBSLN injuries, and may serve to optimize voice outcomes during thyroidectomy. CTM needle electrodes are safe and tolerated well.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1436-1442, 2021.

Carotid Endarterectomy Requiring Removal of the Superior Horn of Thyroid Cartilage: Case Report and Literature Review

Carotid endarterectomy (CEA) is an established surgical procedure for carotid stenosis. We present the case of a 74-year-old man who underwent CEA for symptomatic internal carotid artery (ICA) stenosis. During the operation, we found that the hyoid bone (HB) and the superior horn of the thyroid cartilage covered the carotid sheath, preventing adequate visualization. Since this was anticipated based on preoperative examinations, the superior horn of thyroid cartilage was removed with the help of an otorhinolaryngologist. The HB was preserved because it could be retracted, and thereafter we performed CEA. Although CEA is a common procedure, the HB and thyroid cartilage are rarely involved in the operation. We present a case report including literature review of acute cerebrovascular syndrome (ACVS) due to HB and thyroid cartilage obstruction.

Factors Influencing the Relationship of the External Branch of the Superior Laryngeal Nerve with the Superior Pole Vessels of the Thyroid Gland

Objectives:

In a thyroidectomy, the external branch of the superior laryngeal nerve (EBSLN) is a potential risk during the superior pole dissection due to its close anatomical relationship with the superior thyroid artery and its highly variable anatomy. In this study, we aimed to evaluate the relationship of EBSLN with the superior pole considering Cernea classification and the factors affecting this relationship.

Methods:

The data of thyroidectomized 126 patients (95 female, 31 male) with 200 neck sides (mean age of 45.6±12.1 years) using intraoperative neuromonitoring (IONM) for the EBSLN exploration were evaluated retrospectively. During the superior pole dissection, the EBSLN course was classified according to Cernea classification after being confirmed with IONM. It was defined as a large goiter in the case of the thyroid lobe volume being >50 cc. The factors influencing the presence of type 2b, which has the highest risk of injury, were evaluated using logistic regression analysis.

Results:

Of the 200 EBSLNs evaluated, 52 (26%) were type 1, 134 (68%) were type 2a, and 14 (7%) were type 2b. The mean volumes of the resected thyroid lobes were 22±25 cc (min-max: 2-136), 23±20 cc (3-163), and 39±24 cc (3-65) in type 1, 2a and 2b, respectively, which was significantly higher in type 2b (p=0.035). Presence of large goiter rates were 5.8% (n=3), 8.2% (n=11), 64.3% (n=9) in type 1, 2a, and 2b, respectively, and was significantly higher in type 2b (p=0.0001). There was no significant difference between EBSLN Cernea types concerning age, sex, nerve side, presence of cancer and hyperthyroidism. In logistic regression analysis, large goiter was the only independent factor associated with Cernea type 2b. In case of a lobe volume greater than 50 cc, the probability of type 2b presence was approximately 25 times higher (p<0.001, odds ratio: 25.262).

Conclusion:

Type 2b course of EBSLN is more common in large goiters, and it is 25 times more likely to be seen in the presence of a lobe volume over 50 cc. Thus, it should be considered that the probability of this high-risk course is significantly higher in large goiters.

Voice modulation, self-perception and motor branch of the superior laryngeal nerve

OBJECTIVES

Vocal morbidity resulting from damage to the motor branch of the superior laryngeal nerve (SLN) after endocrine surgery is well known, but diagnosis is often delayed. The present study aimed to quantify these vocal changes acoustically (main objective), and correlate this with the vocal complaints of patients with suspected SLN motor impairment (secondary objective).

MATERIAL AND METHODS

Thirty females patients with suspected injury of the SLN cricothyroid branch (CT-) were compared to 30 patients without postoperative vocal impairment (CT+) and to 30 control subjects. Mean, minimal and maximal fundamental frequencies (F0mean, F0min and F0max) and vocal range were measured on /e/ at high frequency, sirens (glissandi), a reading text, and minimal intonation pairs. Subjective vocal impairment was evaluated on the Voice Handicap Index (VHI).

RESULTS

A lowering of F0mean associated with vocal range reduction by one fifth (in the reading text) seemed to be specific to CT- patients. Production of questions was affected, with differences in melodic curve and attack. Thyroidectomy within 2 months in itself (without suspected SLN cricothyroid branch injury) also affected these parameters, but to a lesser degree. CT- patients reported greater voice impairment than CT+ patients or controls (P=0.0004).

CONCLUSION

Alterations in speech intonation, quantified on minimal pair test, and self-assessed vocal handicap (VHI) are tools that can easily be used in daily practice to screen for SLN motor branch lesion.

Neural Monitoring of the External Branch of the Superior Laryngeal Nerve During Transoral Thyroidectomy

OBJECTIVES/HYPOTHESIS

There is no study regarding intraoperative neural monitoring (IONM) of the external branch of the superior laryngeal nerve (EBSLN) during transoral thyroidectomy. The objective of this study was to evaluate the feasibility and success rate of electrical identification of the EBSLN during transoral robotic or endoscopic thyroidectomy.

STUDY DESIGN

Case series study.

METHODS

We studied a cohort of 76 patients (87 nerves at risk, (NARs)) who underwent transoral robotic or endoscopic thyroidectomy and simultaneous intermittent IONM between July 2017 and May 2019. We performed the standard IONM procedure plus routine neural monitoring of the EBSLN. IONM and surgical outcome data were prospectively collected.

RESULTS

Sixty-one patients underwent the robotic procedure, and 15 patients underwent the endoscopic procedure. Thirty-seven external branches of the superior laryngeal nerves at risk (42.5%) were electrically identified using electromyography signals (31 NARs, 35.6%) or cricothyroid muscle twitches (6 NARs, 6.9%). The mean pre-(S1) and post-dissection (S2) amplitudes of the EBSLN were 372 ± 147 and 351 ± 159 μV, respectively. The identification rates were not different between the robotic and endoscopic procedures. In comparing the early 20 NARs (18 patients) and the later 67 NARs (58 patients), the identification rate was higher in the later cases, although the difference was not statistically significant (25.0% vs. 47.8%, P = .079).

CONCLUSION

IONM of the EBSLN is feasible and useful in identifying and preserving the nerve during transoral thyroidectomy, although the identification rate of the nerve is relatively low.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E671-E676, 2021.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Thyroid Disease in Adults

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate thyroidectomy.

BACKGROUND

Surgical management of thyroid disease has evolved considerably over several decades leading to variability in rendered care. Over 100,000 thyroid operations are performed annually in the US.

METHODS

The medical literature from 1/1/1985 to 11/9/2018 was reviewed by a panel of 19 experts in thyroid disorders representing multiple disciplines. The authors used the best available evidence to construct surgical management recommendations. Levels of evidence were determined using the American College of Physicians grading system, and management recommendations were discussed to consensus. Members of the American Association of Endocrine Surgeons reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines analyze the indications for thyroidectomy as well as its definitions, technique, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Fine Needle Aspiration Biopsy Diagnosis, Molecular Testing, Indications, Extent and Outcomes of Surgery, Preoperative Care, Initial Thyroidectomy, Perioperative Tissue Diagnosis, Nodal Dissection, Concurrent Parathyroidectomy, Hyperthyroid Conditions, Goiter, Adjuncts and Approaches to Thyroidectomy, Laryngology, Familial Thyroid Cancer, Postoperative Care and Complications, Cancer Management, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal surgical management of thyroid disease.

Anterior cervical discectomy and fusion requiring resection of the superior horn of thyroid cartilage: case report

Anterior cervical discectomy and fusion (ACDF) is the most common surgical procedure utilized for degenerative diseases of the cervical spine. The authors present the case of a 64-year-old man who underwent an ACDF for degenerative changes causing cervical stenosis with myelopathy. The patient's symptoms consisted of pain and weakness of the bilateral upper extremities that slowly progressed over 1.5 years. During the procedure, the superior horn of the thyroid cartilage impeded proper retraction, preventing adequate visualization due to its prominent size. At this point, otorhinolaryngology was consulted, which allowed for safe resection of this portion of the thyroid cartilage while preserving nearby critical structures. With the frequent usage of this surgical approach for various etiologies, the importance of proper recognition and consultation is paramount. Encountering prominent thyroid cartilage resulting in surgical obstruction has not been described in the literature and this report represents a paradigm for the proper course of action.

Comparative study of gasless endoscopic selective lateral neck dissection via the anterior chest approach versus conventional open surgery for papillary thyroid carcinoma

BACKGROUND

Although there has been increasing interest in aesthetical approaches for treating patients with papillary thyroid carcinoma (PTC), there have been no studies comparing the safety and effectiveness of gasless endoscopic selective lateral neck dissection (SLND) via the anterior chest approach (ACA) with that of conventional open surgery (OPEN) for papillary thyroid carcinoma.

METHODS

A total of 91 patients with PTC who underwent either gasless endoscopic thyroidectomy, central compartment neck dissection and SLND via the ACA or conventional open surgery between Nov. 2008 to Dec. 2018 were included. Primary outcomes and demographic data were compared between the two groups.

RESULTS

Thirty-one patients were in the ACA group and 60 were in the OPEN group. The ACA group was younger and had a longer operative time but less intraoperative hemorrhage (P < 0.001 for all). There were no differences in other clinicopathological features. During the median follow-up of 48 months (ACA group) and 35 months (OPEN group), no recurrence on US/CT was found. The patients in the ACA group had better cosmetic results assessed postoperatively.

CONCLUSION

It appeared that gasless endoscopic selective lateral neck dissection via the anterior chest approach achieved comparable safety and effectiveness as conventional open surgery for PTC and resulted in better cosmetic results.

Visual and electrophysiological identification of the external branch of superior laryngeal nerve in redo thyroid surgery compared with primary thyroid surgery

Purpose

Thyroid reoperations are surgically challenging because of significant anatomical variance. Visual and functional identification of the external branch of the superior laryngeal nerve (EBSLN) were studied in 2 groups of patients who underwent primary and redo thyroid surgery.

Methods

This study was conducted on 200 patients: 100 patients with redo and 100 patients with primary thyroid surgery. In addition to visual identification, nerve branches were functionally identified by intraoperative nerve monitoring (IONM). Visual, functional, and total identification rates of the EBSLN in both primary and redo surgery were determined and compared between the 2 groups.

Results

We attempted to identify 138 and 170 EBSLNs at risk in redo and primary surgery, respectively. Visual identification rates were 65.3% and 30.4% (P < 0.001) in primary and redo surgery groups, respectively. In total, 164 (96.5%) and 97 EBSLNs (70.3%) were identified in primary and redo surgery, respectively (P < 0.001), including the use of IONM. In primary surgery group, 53 nonvisualized EBSLNs of 164 identified nerves (32.3%) were determined by IONM alone. In redo surgery group, 55 of 97 identified nerves (56.7%) were determined by IONM alone (P < 0.001).

Conclusion

Both visual and total identification rates of the EBSLN are significantly decreased in reoperative thyroidectomy. IONM increases the total identification rate of the EBSLN in primary and redo thyroid surgery. Electrophysiological monitoring makes a substantial contribution to the identification of the EBSLN both in primary and especially in redo thyroid surgery.

Importance of incorporating intraoperative neuromonitoring of the external branch of the superior laryngeal nerve in thyroidectomy: A review and meta-analysis study

BACKGROUND

Voice changes are frequently reported after thyroidectomy due to injury to the external branch of the superior laryngeal nerve (EBSLN) and paralysis of the cricothyroid muscle, The objective is to evaluate the advantage of intraoperative neuromonitoring (IONM) in identifying EBSLN during thyroid surgery.

METHODS

Data sources were MEDLINE, PubMed, Web of Science, and Cochrane Library from January 1, 1995, through July 1, 2018. Published studies of adult patients who had thyroid surgery and an attempt to identify EBSLN done by conventional methods and/or IONM were selected.

RESULTS

Seven studies met all inclusion criteria. Patients who had IONM during thyroid surgery had a significantly increased number of identified EBSLN at risk, compared to the control group.

CONCLUSION

The use of IONM during open thyroid surgery increases EBSLN identification/visualization, and hence it may decrease the incidence of post-thyroidectomy voice disorders.

Variations of the origin of superior thyroid artery and its relationship with the external branch of superior laryngeal nerve

Introduction

The superior thyroid artery, the main atrial supply of neck region, is branched from the external carotid artery as a first branch, but it may also arise from the common carotid artery and its bifurcation. The external branch of superior laryngeal nerve runs parallel to it and later crossing the artery either above or below the upper pole of the thyroid gland.

Objective

This study aimed at evaluating the variations of the origin of superior thyroid artery and its relationship with the external branch of the superior laryngeal nerve.

Methods

A descriptive study was conducted on 43 embalmed cadavers. The anterior triangle of the neck region was dissected bilaterally. The presence or absence of STA and its origin, branching pattern, relationship with the external branch of the superior laryngeal nerve, level of origin in relation to the lamina of the thyroid cartilage and level of carotid bifurcation were observed and recorded.

Result

The superior thyroid artery arises from the external carotid artery in 44.2%, common carotid bifurcation in 27.9% and common carotid artery in 26.7% of cadavers. In one of the cadaver, the superior thyroid artery arises from lingual artery. The origin of superior thyroid artery was significantly associated with its branching pattern and level of common carotid artery bifurcation. The mean distance from the upper pole of the thyroid gland to the level where an external branch of superior laryngeal nerve turns medially from superior thyroid artery was found to be 1.04cm.

Conclusion

The wide range of variations of the superior thyroid artery on its origin and relationship with adjacent structures is a common phenomenon. The clinicians should be aware of those variations.