Comparison of Injection Laryngoplasty With and Without Ultrasound Marking After Thyroid Surgery

OBJECTIVES

This study aimed to assess the clinical efficacy of injection laryngoplasty using ultrasound marking in patients with unilateral vocal fold paralysis after thyroidectomy compared with injection laryngoplasty without ultrasound marking.

METHODS

Ten patients with unilateral vocal fold paralysis after thyroidectomy were retrospectively analyzed. There were five patients in the ultrasound marking group and matched five patients in the non-ultrasound marking group. Auditory-perceptual evaluation, acoustic analysis, aerodynamic analysis, and Voice Handicap Index-30 were performed on all patients before and 1 month after injection laryngoplasty.

RESULTS

In all patients, auditory-perceptual parameters and the Voice Handicap Index-30 revealed statistically significant improvements following injection laryngoplasty. No adverse effects were observed in any patient. The Voice Handicap Index-30 and the injection laryngoplasty procedure time were substantially reduced in the ultrasound marking group compared to that in the non-ultrasound marking group. However, other parameters did not exhibit a statistically significant difference between the two groups before and 1 month after injection laryngoplasty.

CONCLUSION

Injection laryngoplasty with ultrasound marking is an easy, rapid, and convenient method for patients who experienced unilateral vocal fold paralysis following thyroidectomy.

Proposal of integrated clinical pathway in the management of perioperative recurrent laryngeal nerve injury post thyroid and parathyroid surgery

Early intervention is the current paradigm shift in the management of recurrent laryngeal nerve (RLN) injury post thyroidectomy and parathyroidectomy. Thus, an integrated clinical pathway is needed to enable early detection of RLN injury. A prospective longitudinal study was conducted from 2015 until 2021 in a single tertiary centre. A clinical pathway was developed where routine perioperative laryngeal assessments were implemented for all patients who underwent thyroidectomy and parathyroidectomy. Following an RLN injury, early surgical intervention was performed for unilateral vocal fold paralysis (UVFP). Data on patient demographics, risk factors, timing of RLN injury detection and type of intervention received were recorded in a proforma and analysed. 397 patients were included, involving 660 nerves at risk. The incidences of permanent RLN injury following thyroidectomy and parathyroidectomy were 5% and 1.8% respectively. The usage of intraoperative neuromonitoring was the only significant factor that affected the RLN injury according to multivariate analysis. 15% of RLN injuries were detected intraoperatively and 98% within two days. 70% of patients with UVFP received intervention in less than two weeks. The integrated clinical pathway has improved the validity of RLN injury incidence. It allows early detection of RLN injury and facilitates immediate intervention.

Ultrasonic Vocalization Acoustics After Recurrent Laryngeal Nerve Injury and Recovery

OBJECTIVES

The lack of well-defined functional acoustic correlates of vocal fold paralysis in animal models creates challenges for translating basic science studies of recurrent laryngeal nerve (RLN) injury to patients with vocal fold paralysis. Capitalizing on natural communicative rodent ultrasonic vocalizations (USVs), this study aimed to (1) investigate the impact of RLN injury on USV acoustics in both acute and chronic stages of RLN injury and (2) to identify USV parameters with the greatest ecological validity specific to RLN injury.

METHODS

USVs were recorded over 2 weeks (acute) in 16 animals and over 30 weeks (chronic) in 8 animals using two USV elicitation paradigms (n = 16 non-elicited, spontaneous; n = 8 elicited, sexually paired). USV acoustic characteristics from a list of possible parameters (duration, principal frequency, complexity, power, and tonality) were compared across USV elicitation paradigms and time points (before RLN injury, 2 weeks after injury, and 30 weeks after injury).

RESULTS

The USV parameters most impacted by RLN injury were frequency, power, and tonality, with significant decreases in all three parameters in both non-elicited/spontaneous and sexually elicited USV elicitation paradigms. All USV parameters were stable across 30 weeks after RLN injury.

CONCLUSION

USV acoustic frequency, power, and tonality best characterize RLN injury and are stable over time, demonstrating their ecological utility in characterizing RLN injury and recovery. Furthermore, their stability can ensure accurate outcome metrics for future studies. Finally, these parameters have direct translation to humans with vocal fold paralysis.

LEVEL OF EVIDENCE

N/A.

Timing of parathyroidectomy after kidney transplantation: A cost-effectiveness analysis

INTRODUCTION

Parathyroidectomy is the definitive treatment for tertiary hyperparathyroidism post-kidney transplantation. However, cinacalcet-based medical management is increasingly used as an alternative. The financial consequences of each treatment remain unclear. We aimed to identify the most cost-effective strategy for managing hyperparathyroidism from the kidney transplantation recipient's perspective.

METHODS

We constructed a patient-level discrete event simulation model to compare parathyroidectomy and cinacalcet-based medical management. The effects of hyperparathyroidism on allograft survival and all-cause mortality were considered in the discrete event simulation model with a time horizon of 15 years. Our base case was a 55-year-old kidney transplantation recipient with persistent hyperparathyroidism and hypercalcemia. The primary outcome was the cost-effectiveness measured by cost per quality-adjusted life years.

RESULTS

The monthly out-of-pocket cost of cinacalcet ranged from $12 to $288, depending on insurance coverage, with a base case cost of $150. Our base case analysis showed that parathyroidectomy was the dominant treatment with lesser cost ($1,315 vs $7,147) and greater effectiveness (3.17 quality-adjusted life years and 2.92 quality-adjusted life years) than cinacalcet. One-way sensitivity analysis on the cinacalcet treatment duration showed that parathyroidectomy became more cost-effective at 9 months. Two-way sensitivity analysis on the cost of cinacalcet and the duration of treatment with cinacalcet showed that as the monthly cost of cinacalcet increases, the expense of cinacalcet-based medical management quickly exceeds the cost of parathyroidectomy.

CONCLUSION

Parathyroidectomy becomes more cost-effective for kidney transplantation recipients with tertiary hyperparathyroidism when they require cinacalcet-based medical management for more than 9 months. As part of shared decision-making, it is important to discuss the financial costs involved in treating tertiary hyperparathyroidism.

Factors Associated With Injury to Recurrent Laryngeal Nerve in Patients Undergoing Surgery for Thyroid Cancer: A Single-centre Study Using Translaryngeal Ultrasound

AIMS

Intraoperative injury to the recurrent laryngeal nerve (RLN) is a serious complication occurring more frequently in patients with thyroid cancer than in those with benign thyroid diseases. However, data on the risk factors for RLN injury among patients with thyroid cancer are scarce. Currently, RLN injury is diagnosed by laryngoscopy, but translaryngealultrasonography (TLUS), which is less invasive, appears to have a similar accuracy. Herein, we analysed risk factors ofintraoperative RLN injury in patients with thyroid cancer and assessed the diagnostic performance of TLUS.

PATIENTS AND METHODS

In this prospective study, we enrolled patients undergoing surgery for thyroid cancer from October 2020 to October 2021. Medical and surgical variables were analysed as risk factors of RLN injury. TLUS was compared with laryngoscopy in diagnosing RLN injury.

RESULTS

There were 185 patients who underwent 196 surgeries. Of all surgeries, 23 (11.7%) caused RLN injury ascertained on laryngoscopy. Compared with laryngoscopy, TLUS displayed high sensitivity (97.7%; 95%CI: 94.3%-99.4%) and specificity (100%; 95% CI: 82.4%-100%). Before surgery, medical and surgical characteristics did not differ significantly between patients with or without RLN injury, but RLN entrapment by tumour was more frequent in those with the injury (P < 0.001). The risk of RLN injury was increased in patients undergoing thyroidectomy with lateral neck dissection (OR = 4.53; 95% CI: 1.29-14.32) and in those with lymph node metastases (OR = 2.76; 95% CI: 1.03-7.01).

CONCLUSION

Intraoperative RLN injury in patients with thyroid cancer is more common after operations requiring greater resections and with lymph node involvement. TLUS could be used to diagnose RLN injury.

Scaffold-Forming Collagen and Motor-Endplate Expressing Muscle Cells for Porcine Laryngoplasty

OBJECTIVE

Vocal fold paralysis impairs quality of life, and no curative injectable therapy exists. We evaluated injection of a novel in situ polymerizing (scaffold-forming) collagen in the presence and absence of muscle-derived motor-endplate expressing cells (MEEs) to promote medialization and recurrent laryngeal nerve (RLN) regeneration in a porcine model of unilateral vocal fold paralysis.

METHODS

Twelve Yucatan minipigs underwent right RLN transection. Autologous muscle progenitor cells were isolated from muscle biopsies, differentiated, and induced to MEEs. Three weeks after RLN injury, animals received injections of collagen, collagen containing MEEs, or saline into the paralyzed right vocal fold. Stimulated laryngeal electromyography and acoustic vocalization were used for function assessments. Larynges were harvested and underwent histologic, gene expression, and further quantitative analyses.

RESULTS

Injections were well-tolerated, with the collagen scaffold showing immunotolerance and collagen-encapsulated MEEs remaining viable. Collagen-treated paralyzed vocal folds showed increased laryngeal adductor muscle volumes relative to that of the uninjured side, with those receiving MEEs and collagen showing the highest volumes. Muscles injected with MEEs and collagen demonstrated increased expression of select neurotrophic (BDNF and NTN1), motor-endplate (DOK7, CHRNA1, and MUSK), and myogenic (MYOG and MYOD) related genes relative to saline controls.

CONCLUSION

In a porcine model of unilateral vocal fold paralysis, injection of in situ polymerizing collagen in the absence and presence of MEEs enhanced laryngeal adductor muscle volume, modulated expression of neurotrophic and myogenic factors, and avoided adverse material-mediated immune responses. Further study is needed to determine long-term functional outcomes with this novel therapeutic approach.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:4988-4997, 2024.

Delayed-onset vocal cord palsy after thyroidectomy occurring despite normal initial post-operative endoscopy

BACKGROUND

Recurrent laryngeal nerve (RLN) injury is a known complication of thyroidectomy. Most cases manifest immediately and are promptly recognized. Rarely, some patients experience delayed-onset vocal cord palsy. This can occur despite normal findings on intra-operative nerve monitoring and initial post-operative endoscopy. This can cause considerable distress for patients, and its incidence and prognosis should be recognized.

METHODOLOGY

We report seven patients experiencing delayed-onset RLN palsy (RLNP) after thyroidectomy. All had normal findings on pre-operative flexible nasoendoscopy (FNE), intra-operative nerve monitoring at conclusion of surgery, and initial post-operative FNE. All diagnoses of RLNP were confirmed on endoscopy. Serial FNE examinations were performed to evaluate recovery.

RESULTS

Of seven patients (43% male, median age 65 years), the median timing of delayed-onset RLNP was 12 (range 9-35) days. RLNP was diagnosed on the unilateral side of surgery in six out of seven patients (86%). All received conservative management, including referral to voice therapy. All seven patients recovered vocal cord function after a median duration of 24 weeks (range 8-52 weeks), and six within ~6 months (28 weeks). The incidence of this complication was 0.1% (among 6607 thyroidectomies).

CONCLUSION

We report the first Australian series of delayed-onset vocal cord palsy after thyroidectomy. We explore its prognosis, discussing different pathophysiological mechanisms and the timeframe for recovery compared to most other RLN injuries. This may assist recognition of a rare complication, reassure patients, and facilitate early intervention to improve a patient's quality of life.

Immediate Ansa cervicalis-to-recurrent laryngeal nerve low-tension anastomosis: A new technique for phonation recovery and bilateral anastomoses to avoid tracheotomy

OBJECTIVE

This case series study investigated the outcomes of an innovative approach, ansa cervicalis nerve (ACN)-to-recurrent laryngeal nerve (RLN) low-tension anastomosis.

METHODS

Patients who received laryngeal nerve anastomosis between May 2015 and September 2021 at the facility were enrolled. The inclusion criteria were patients with RLN dissection and anastomosis immediately during thyroid surgery. Exclusion criteria were cases with anastomosis other than cervical loop-RLN anastomosis or pronunciation recovery time > 6 months. Patients admitted before January 2020 were assigned to group A which underwent the conventional tension-free anastomosis, and patients admitted after January 2020 were group B and underwent the innovative low-tension anastomosis (Dong's method).

RESULTS

A total of 13 patients were included, 11 patients received unilateral surgery, and 2 underwent bilateral surgery. For patients who underwent unilateral anastomosis, group B had a significantly higher percentage of normal pronunciation via GRBAS scale (83.3 % vs. 0 %, p = 0.015) and voice handicap index (66.7 % vs. 0 %, p = 0.002), and shorter recovery time in pronunciation (median: 1-day vs. 4 months, p = 0.001) than those in group A after surgery.

CONCLUSIONS

ACNs-to-RLN low-tension anastomosis with a laryngeal segment ≤1 cm (Dong's method) significantly improves postoperative pronunciation and recovery time. The results provide clinicians with a new strategy for ACN -to-RLN anastomosis during thyroid surgery.

Core needle biopsy for thyroid nodules assessment-a new horizon?

Ultrasound-guided fine-needle aspiration is the standard for evaluating thyroid nodules with a high safety profile and a relatively low number of non-diagnostic cytological findings. Nevertheless, this diagnostic method traditionally has its weak points. Several diagnostic categories such as Bethesda I, III and IV are not reliable for thyroid carcinoma risk assessment. Recent advancements in a core needle biopsy made it possible to use this tool as a new method for thyroid nodules evaluation. The main feature of this method is the use of thin needles (18-21G) and guns with an automatic trigger mechanism. The histological material collected with the use of a core needle biopsy is usually superior to cytological. Therefore, the core needle biopsy can be used as a complementary technique to a standard fine needle aspiration in difficult and dubious cases of thyroid neoplasia with uncertain malignant potential.

A case of recurrent laryngeal nerve paralysis caused by radiofrequency ablation for mediastinal recurrence of lung cancer

Radiofrequency ablation (RFA) has emerged as a potent therapeutic modality for tumor treatment, and offers benefits such as reduced recovery time and minimal damage to nearby tissues. However, RFA is not devoid of complications, notably nerve damage during intrathoracic lesion treatments, which can significantly impact patients' quality of life. This report describes the unique case of a 71-year-old male who experienced hoarseness attributed to injury to the recurrent nerve after RFA for a locally recurrent lung cancer lesion in the mediastinum near the aortic arch. Although RFA has the advantages of a minimally invasive nature and positive outcomes, its risk of nerve injury, specifically in the thoracic region, highlights the need for improved techniques and preventive measures.

The weepy cry - short neural signal bursts in intraoperative neuromonitoring

PURPOSE

This study aimed to establish an in-vitro alternative to existing in-vivo systems to analyze nerve dysfunction using continuous neuromonitoring (C-IONM).

METHODS

Three hundred sixty-three recurrent laryngeal nerves (RLN) (N(pigs) = 304, N(cattle) = 59) from food industry cadavers were exposed by microsurgical dissection following euthanasia. After rinsing with Ringer's lactate, they were tempered at 22 °C. Signal evaluation using C-IONM was performed for 10 min at 2 min intervals, and traction forces of up to 2N were applied for a median time of 60 s. Based on their post-traumatic electrophysiological response, RLNs were classified into four groups: Group A: Amplitude ≥ 100%, Group B: loss of function (LOS) 0-25%, Group C: ≥ 25-50%, and Group D: > 50%.

RESULTS

A viable in-vitro neuromonitoring system was established. The median post-traumatic amplitudes were 112%, 88%, 59%, and 9% in groups A, B, C, and D, respectively. A time-dependent further dynamic LOS was observed during the 10 min after cessation of strain. Surprisingly, following initial post-traumatic hyperconductivity, complete LOS occurred in up to 20% of the nerves in group A. The critical threshold for triggering LOS was 2N in all four groups, resulting in immediate paralysis of up to 51.4% of the nerves studied.

CONCLUSION

Consistent with in-vivo studies, RLN exhibit significant intrinsic electrophysiological variability in response to tensile forces. Moreover, nerve damage progresses even after the complete cessation of strain. Up to 20% of nerves with transiently increased post-traumatic amplitudes above 100% developed complete LOS, which we termed the "weepy cry." This time-delayed response must be considered during the interpretation of C-IONM signals.

Factors predicting remission in hyperthyroid patients after low-dose I-131 therapy: 20 years retrospective study from a tertiary care hospital

OBJECTIVE

To assess the therapeutic outcome and factors predicting remission in hyperthyroid patients treated with low-dose I-131 (radioactive iodine) from a tertiary care hospital in South India.

METHODS

This 20-year single-institutional retrospective study was carried out on 3891 hyperthyroid adult patients. Only those patients with complete clinical records were audited. Selection criteria were based on patients with scintigraphic diagnosis of either Graves' disease (GD), toxic multinodular goitre (TMNG) or autonomous toxic nodule (ATN) and the records of those who received low-dose I-131 therapy (LDT) between March 2000 and 2020 at Amrita Institute, Cochin were analysed. SPSS 10 software was used for statistical analysis.

RESULTS

The records of 3891 hyperthyroid predominantly female patients were analysed. 65% patients had GD, 33% had TMNG and 3% were ATN. High rates of remission as early as 12 weeks (in 61% patients) was observed with a single dose of LDT while on strict iodine-free diet for 3-4 weeks prior to LDT. Study reveals that those with lower free T4 (fT4), small goitre (thyroid volume < 25 cm3), < 15% thyroid trapping function, shorter time duration from onset of hyperthyroidism to LDT, and treatment-naïve patients were factors determining high remission rates. Mann Whitney U test and Chi-square test was used to correlate variables in the remission and relapse groups. We found a positive correlation between fT4, thyroid volume (r = 0.35, p < 0.01) and trapping function (r = 0.34, p < 0.01), which were independent of age, sex, body mass index and TSH levels in our study.

CONCLUSION

High therapeutic outcome was observed with a single dose of LDT while on iodine-free diet. Remission with single dose of LDT occurred in 90% patients by 5th month. Of them 56% patients were treatment naive prior to LDT. LDT is thus a safe and effective therapy in hyperthyroid patients and can be recommended as a primary modality of management.

Defining the Thyroid-RLN Entry Triangle for Enhanced Recurrent Laryngeal Nerve Exposure in TOETVA: A Retrospective Study

BACKGROUND

Injury to the recurrent laryngeal nerve (RLN) and parathyroid glands (PGs) are the most common and serious complications during the transoral endoscopic thyroidectomy vestibular approach (TOETVA), and their exposure and protection are the most important factors affecting the operation time. Here, we report a novel anatomical landmark and surgical method to shorten the operative time and reduce the chance of injury to the RLN and PGs.

METHODS

According to the different exposure methods of the RLN, patients were divided into the experimental group (from top to bottom, E-group) and the comparison group (from outside to inside, C-group), and 1:1 propensity score-matching (PSM) was performed. The demographics, operative data, postoperative data, and postoperative complications were analyzed by comparing the 2 groups.

RESULTS

After PSM, a total of 206 patients were included. Except for tumor size, there were no significant differences between the 2 groups in terms of sex, age, body mass index, presence of Hashimoto's thyroiditis, or extent of surgery. Compared with the C-group, the operative time, in minutes, of the E-group was significantly shorter (hemithyroidectomy with central neck dissection (CND), C = 111.81 ± 25.83 vs E = 100.52 ± 16.47, P = .002 and bilateral thyroidectomy with CND, C = 177.87 ± 36.61 vs E = 156.05 ± 25.60, P = .004), the exposure time, in minutes, of the RLN was reduced (hemithyroidectomy with CND, C = 23.31 ± 7.07 vs E = 11.41 ± 2.75, P < .001 and bilateral thyroidectomy with CND, C = 45.64 ± 14.84 vs E = 21.76 ± 5.57, P < .001). The rate of postoperative temporary PGs and RLN injuries were also reduced (transient hypoparathyroidism, C = 13% vs E = 4%, P = .023 and transient RLN palsy, C = 10% vs E = 2%, P = .017). In addition, the remaining parameters such as the amount of bleeding, number of lymph node metastases, postoperative hospital stay, visual analog scale pain score, recurrence rate, and other complication rates were not significantly different between the 2 groups.

CONCLUSION

It is safe and feasible to construct Thyroid-RLN Entry Triangle (Peng's Triangle) for PGs and RLN protection in TOETVA. It is beneficial to shorten the operation time and reduce postoperative complications, both worthy of clinical promotion.

TRIAL REGISTRATION

This study was registered at the Chinese Clinical Trial Registry (UIN: ChiCTR2300067673, https://www.chictr.org.cn) in accordance with the World Medical Association's Declaration of Helsinki, 2013.

Temporal Expression of Hox Genes and Phox2b in the Rat Nucleus Ambiguus During Development: Implications on Laryngeal Innervation

OBJECTIVES

Recurrent laryngeal nerve (RLN) injury results in synkinetic reinnervation and vocal fold paralysis. Investigation of cues expressed in the developing brainstem that influence correct selective targeting of intrinsic laryngeal muscles may elucidate post-injury abnormalities contributing to non-functional reinnervation. Primary targets of interest were Hoxb1 and Hoxb2, members of the Hox family that create overlapping gradients in the developing brain, and their target Phox2b, a transcription factor necessary for cranial nerve branchio- and visceromotoneuron survival.

METHODS

Rat embryos at developmental days E14, E16, E18, and E20 (4 animals/age) were sectioned for RNA in situ hybridization to detect Hoxb1, Hoxb2, and Phox2b mRNA within the brainstem. Slides were costained with Islet1 antibody for identification of the nucleus ambiguus. Results were confirmed using immunohistochemistry. Sections were imaged on a confocal microscope. RNA and protein expressions were quantified using QuPath. Statistical analyses were performed using R.

RESULTS

Hoxb1, Hoxb2, and Phox2b expressions varied according to embryologic age. Hoxb1 and Hoxb2 expression peaked at E16, with significant decreases at E18 and E20 (one-way ANOVA p = 0.001 for both). Phox2b expression was highest at E14 and trended downward with increased embryologic age (one-way ANOVA p = 0.005).

CONCLUSION

Peak expression of Hoxb1 and Hoxb2 is observed at time points when the RLN arrives at the larynx and begins to branch toward individual muscles, positioning these gene products to be involved in cueing laryngeal motoneuron identity and target identification. Higher expression of Phox2b earlier in development suggests a role in laryngeal motoneuron formation.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:3462-3471, 2023.

Expression of Glial Cell-Derived Neurotrophic Factor Receptors Within Nucleus Ambiguus During Rat Development

OBJECTIVE

The nucleus ambiguus (NAmb) is a column of neurons in the medulla oblongata, involved in bulbar functions. Expression of Glial Cell-Derived Neurotrophic Factor (GDNF) and its receptors (GDNFR) is observed within the cell bodies during reinnervation following recurrent laryngeal nerve (RLN) injury. Little is known regarding GDNFR expression in the formation of the NAmb and the laryngeal innervation during embryogenesis. Understanding the timing and pattern of GDNFR expression in embryogenesis versus after RLN injury may provide insights into therapeutic targets for regeneration after RLN injury.

STUDY DESIGN

Laboratory experiment.

METHODS

Rat brainstems at E14.5/E16.5/E18.5/E20.5/adult were stained for GDNFR: GFRα-1/GFRα-2/GFRα-3/Ret. Islet1 and choline acetyltransferase were used as cell body markers. Sections were observed using fluorescent microscopy and quantified through manual cell counting.

RESULTS

Expression of GFRα-1, GFRα-3, and Ret was identified within the NAmb, hypoglossal, and facial nuclei of the adult medulla. During development, GFRα-1 immunoreactivity was seen at E20.5. GFRα-2 expression was not observed at any timepoint. GFRα-3 expression began at E16.5. Ret expression within nerve fibers in the NAmb were observed beginning at E14.5, but never in the cell bodies.

CONCLUSION

Embryonic GDNFR expression in the NAmb differs from that of the adult after RLN injury. The developing brainstem experienced upregulation at discrete timepoints with signaling sustained through adulthood. In contrast, adult RLN-transected rats experienced patterns of up and down regulation. GFRα-1 may contribute to muscle targeting and neuromuscular junction maturation, GFRα-3 may contribute to both, as well as axon guidance. It is likely that GDNF is functioning via a Ret-independent pathway.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:2240-2247, 2023.

Modern Surgical Techniques of Thyroidectomy and Advances in the Prevention and Treatment of Perioperative Complications

Thyroid cancer is the most common cancer of the endocrine system, and, in recent years, there has been a phenomenon of overdiagnosis followed by subsequent overtreatment. This results in an increasing number of thyroidectomy complications being faced in clinical practice. In this paper, we present the current state of knowledge and the latest findings in the fields of modern surgical techniques, thermal ablation, the identification and assessment of parathyroid function, recurrent laryngeal nerve monitoring and treatment and perioperative bleeding. We reviewed 485 papers, from which we selected 125 papers that are the most relevant. The main merit of this article is its comprehensive view of the subject under discussion-both general, concerning the selection of the appropriate method of surgery, and particular, concerning the selection of the appropriate method of prevention or treatment of selected perioperative complications.

Variant anatomy of non-recurrent laryngeal nerve: when and how should it be taught in surgical residency?

INTRODUCTION

While the performance of a thyroidectomy is generally associated with a low risk of injury to the recurrent laryngeal nerve (RLN), the presence of a non-recurrent nerve (NRLN) increases the risk of this complication. Generally, the intraoperative detection via visual appreciation of variant anatomy of the RLN has been regarded as poor, possibly due to a lack of knowledge of both the normal and aberrant anatomy of the RLN.

MATERIALS AND METHODS

Articles for the review were searched through PubMed using the search terms and their combinations: "non-recurrent laryngeal nerve," "thyroidectomy," "injury," "palsy," "variant anatomy," and "residency," from January 1, 2000, to December 2022. Papers considered for the review were the articles published in English, with additional classic and articles of surgical importance retrieved from the reference list of papers. Only papers relevant to the scope of the review were considered for this review.

FINDINGS

The NRLN has been found to be associated with concurrent vascular abnormalities, such as the presence of an aberrant right subclavian artery (ARSA) or an arteria lusoria originating from the aortic arch. However, it seems that both the normal as well as aberrant anatomy of the RLN is currently not emphasized enough during postgraduate surgical training. With the increased use of intraoperative neuromonitoring (IONM), detection of NRLN has become possible through appropriate neural mapping during thyroid surgery, besides other pointers such as visualization during surgery, computerised tomography, and duplex ultrasound scans to visualize the variant vascular anatomy. There is also a possible role for cadaveric courses, either during medical school or in a post-graduate setting-adapted to the student's level to teach the variant anatomy. With the development of newer techniques such as artificial intelligence, there are potential new options for teaching and training anatomy in the near future.

CONCLUSIONS AND RELEVANCE

Adequate knowledge of the normal and aberrant anatomy of the RLN remains essential for the best outcomes in thyroid surgery, even in the era of the IONM. Moving forward, the knowledge of (aberrant) anatomy should be made an integral part of the core competencies of both medical students and surgical trainees. It is imperative that leaders of the different field work closely together to combine their knowledge towards providing their trainees with the best possible training options.

The Role of Primary Repair of the Recurrent Laryngeal Nerve during Thyroid/Parathyroid Surgery in Vocal Outcomes-A Systematic Review

Recurrent laryngeal nerve (RLN) injury is a well and long-known complication of thyroid and parathyroid surgery that significantly affects the quality of life of patients. Despite the advances in surgical techniques and technology, it still occurs in clinical practice either as temporary paresis or as permanent paralysis of the corresponding vocal cord. The purpose of the current systematic review is to examine the value of intraoperative repair of the RLN in voice restoration. A systematic review of the existing literature was conducted using PubMed, Scopus, Cochrane Library, and Google Scholar databases according to the PRISMA guidelines. The systematic review resulted in 18 studies, which met the inclusion criteria. An improvement in phonatory function and voice quality was observed in all these studies after immediate RLN reconstruction (not always statistically significant). This improvement appears to be comparable to or even higher than that achieved with other methods of repair, and in some cases, the improvement approaches levels found in normal subjects. Intraoperative RLN reconstruction is not widely used in clinical practice, but the evidence so far makes it a viable and safe alternative to traditional techniques with better long-term results, as it prevents the occurrence of atrophy of the vocal cord and should be considered in the operating room if possible.

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.

Comparison of Short and Long-Term Results after Injection Laryngoplasty with Radiesse® Voice and Thyroplasty Type I in Unilateral Vocal Fold Palsy

OBJECTIVES

Unilateral vocal fold palsy independently of etiology results in glottic insufficiency leading to unfavorable short or long-term impact on voice quality. Our aim was to evaluate the effect of injection laryngoplasty using Radiesse® Voice and thyroplasty type I on glottic closure, voice quality and aerodynamics by comparing preoperative, short- and long-term results.

MATERIALS AND METHODS

Data of 32 consent patients were reviewed between 2012 and 2023. All patients underwent either injection laryngoplasty (14 patients) or thyroplasty type I (18 patients) under local anesthesia. Maximum phonation time, glottic closure based on videolaryngostroboscopy, VHI-30 values and GRBAS scale were recorded prior, short-term (3 month) and long-term (12 months) after procedures for statistical comparison. Friedman test, Mann-Whitney test and Wilcoxon signed rank tests were used for statistical analysis.

RESULTS

In injection laryngoplasty group, we found significant improvement in maximum phonation time (p = 0.002), grade of hoarseness (p = 0.002) and breathiness (p = 0.000) when comparing results before and short-term after procedure. In thyroplasty type I group we saw significant improvement of maximum phonation time (p = 0.000), glottic insufficiency (p = 0.000), all three VHI-30 components (p = 0.000), as well as grade of hoarseness, breathiness (both p = 0.000) and roughness (p = 0.011) of GRBAS scale when comparing voice outcome before and short-term after procedure. There was no significant difference in voice outcome results neither between short and long-term results nor between the two groups in any parameter.

CONCLUSION

These results demonstrate both short and long-term efficiency of injection laryngoplasty and thyroplasty type I in the improvement of voice quality and glottic closure.

Thyroid Surgery in Children: A 5-Year Retrospective Study at a Single Paediatric Surgical Center and Systematic Review

The aim of this study was to analyse and evaluate our 5-year experience in paediatric thyroid surgery, as well as the specificities of this kind of surgery in the literature. This retrospective study was based on 19 operations in 17 patients aged from 5 to 17 years who were operated on due to thyroid pathology from 2017 until 2022. We presented data on surgical procedures and complications following surgery. Most of the patients were adolescent girls. The most common clinical presentations included enlarged thyroid gland, followed by thyroid nodules and hyperthyroidism. Eight total thyroidectomies, five left lobectomies, five right lobectomies, and three central neck dissections were performed. The most common histopathological diagnosis was hyperplastic diffuse colloid goitre, followed by papillary carcinoma, cystic nodule, follicular adenoma, Hashimoto thyroiditis and toxic adenoma. Postoperative course was uneventful, with four mild complications (one wound infection, one manifest hypocalcaemia, and two transitory recurrent laryngeal nerve paralysis). In our literature review, eighteen full-text articles were included and analysed. This study demonstrated that thyroid surgery in paediatric population is a safe and efficient procedure. Thyroid pathology in children significantly differs from that in the adults, and paediatric surgeons should be included into the team managing such cases.

Analysis of Risk Factors for Phonation Disorders after Thyroid Surgery

Phonation disorders after thyroidectomy are among the most common complications and occur as a result of recurrent laryngeal nerve (RLN) injury. The multivariate analysis of risk factors for phonation disorders after thyroidectomy was assessed. A group of 830 patients with 1500 RLNs at risk of injury during thyroidectomy were analyzed retrospectively. The impact of the method of RLN identification, age, sex, BMI, kind of thyroid surgery, pathology, surgeon’s experience and thyroid volume on vocal cord paralysis was analyzed. We found that the retrosternal goiter and the volume above 100 mL were the most important risk factors for both transient and permanent paralysis. Thyroid cancer had a statistically significant impact on the increase in permanent paralysis, while this indication had practically no impact on transient paralysis. Among patients over 65 years with obesity, the probability of transient complications approximately doubled, with no effect on the permanent paralysis. Men were approximately 1.7 times more likely to develop any type of phonation disorder. Secondary operations more than doubled the risk of transient and permanent vocal cord paralysis. Thyroidectomy with only visual RLN identification was associated with a risk of both transient and permanent vocal cord paralysis almost two times higher, compared to neuromonitoring.

Long-term follow-up of voice changes after cervical mediastinoscopy

Background

Vocal cord palsy after cervical mediastinoscopy is usually reported at less than 1%. However, its incidence might be underestimated and no follow-up studies are available. Our study aimed to evaluate the incidence of voice changes after cervical mediastinoscopy and report on long-term outcomes, including quality of life, after at least one-year follow-up.

Methods

A retrospective cohort study was performed, considering all patients who underwent cervical mediastinoscopy in our center between January 2011 and April 2016. Patients with pre-existing voice changes, voice changes only after pulmonary resection and patients who underwent neoadjuvant chemo(radio)therapy were excluded. Voice changes with full recovery within 14 days were attributed to intubation-related causes. Follow-up questionnaires, including the standardized Voice Handicap Index, were sent to patients with documented voice changes.

Results

Of 270 patients who were included for final analysis, 17 (6.3%) experienced voice changes after cervical mediastinoscopy, which persisted > 2 years in 4 patients (1.5%), causing mild to moderate disabilities in daily living. Twelve patients (out of 17, 71%) were referred for otolaryngology consultation, and paresis of the left vocal cord suggesting recurrent laryngeal nerve injury was confirmed in 10 (3.7% of our total study group). Additionally, 83% of the patients who were referred for otolaryngology consultation received voice treatment. Recovery rate after vocal exercises therapy and injection laryngoplasty was respectively 71% and 33%.

Conclusions

Voice changes after cervical mediastinoscopy is an underreported complication, with an incidence of at least 6.3% in our retrospective study, with persisting complaints in at least 1.5% of patients, leading to mild to moderate disabilities in daily living. These findings highlight the need for appropriate patient education for this underestimated complication, as well as the exploration of possible preventive measures.

Application of Translaryngeal Ultrasound (TLUS) in Patients with Neck Surgery-A Single-Centre, Prospective Cohort Study on Technique Evaluation

PURPOSE

The primary objective of this study was to assess the value of translaryngeal ultrasound (TLUS) in assessing vocal fold (VF) function in patients after thyroid, parathyroid and neck lymph node surgery.

METHODS

A total of 219 patients that underwent 230 surgical procedures were enrolled in this prospective study. The study was conducted from October 2020 to October 2021. Patients' VFs were analysed independently with TLUS and laryngoscopy before and after the surgery. Various TLUS variables, such as vocal folds displacement velocity (VFDV), arytenoids symmetry and angle between VFs, were measured. The questionnaire evaluating discomfort caused to patients by both methods was conducted.

RESULTS

Of the 230 surgeries in this study, 85% were from oncological indications. The incidence of RLN injury was 10.4%. The accuracy of TLUS compared to laryngoscopy was 98.3%, with sensitivity 98.1%, specificity 100%, PPV 100% and NPV 83.3%. Laryngoscopy was found to cause significantly more discomfort than TLUS. VF visibility was lower in men; smokers; and patients with higher BMI (32 vs. 28 kg/m2), multifocal cancer, higher left lobe volume and higher fT3 levels. Arytenoid symmetry VFDV was lower for "e" and "i" right side and "i" left side in injured/disabled VFs/RLN.

CONCLUSIONS

TLUS can be an excellent and non-invasive method of VF evaluation in most patients. There are some technical aspects that can improve its accuracy. Sometimes, RLN injury after the surgery, especially among oncological patients, is unavoidable. Therefore, it is vital to diagnose dysphonia early with convenient methods, such as TLUS.

Improving Outcome of Superior Mediastinal Lymph Node Dissection During Esophagectomy: A Novel Approach Combining Continuous and Intermittent Recurrent Laryngeal Nerve Monitoring

OBJECTIVE

This study aimed at demonstrating the effects and learning curve of utilizing combined intermittent and continuous recurrent laryngeal nerve (RLN) monitoring for lymphadenectomy during esophagectomy.

BACKGROUND

RLN lymphadenectomy is oncologically important but is technically demanding. Vocal cord (VC) palsy as a result from RLN injury, carries significant morbidities.

METHODS

This is a retrospective study of consecutive esophageal squamous cell carcinoma (ESCC) patients who underwent transthoracic esophagectomy from 2010 to 2020. Combined nerve monitoring (CNM) included: CNM which involved a periodic stimulating left vagal electrode and intermittent nerve monitoring which utilized a stimulating probe to identify the RLNs. The integrity of the RLNs was assessed both intermittently and continuously. This technique was introduced in 2014. Patients were divided into "before CNM" and "CNM" groups. The primary outcome was the difference in number of RLN lymph nodes harvested and VC palsy rate. Learning curves were demonstrated by cumulative sum (CUSUM) analysis.

RESULTS

Two hundred and fifty-five patients were included with 157 patients in "CNM" group. The mean number of RLN lymph nodes harvested was significantly higher (4.31 vs 0.45, P < 0.0001) for the "CNM" group. VC palsy rates were significantly lower (17.8% vs 32.7%, P = 0.007). There was an initial increase in VC palsy rate, peaked at around 46 cases. The increase in lymph nodes harvested above the mean plateaued at around 96 cases.

CONCLUSIONS

CNM helped improve bilateral RLN lymphadenectomy. Lymph node harvesting was increased with reduction of VC palsy after a learning curve.

In Vitro Evaluation of Biomaterials for Vocal Fold Injection: A Systematic Review

Vocal fold injection is a preferred treatment in glottic insufficiency because it is relatively quick and cost-saving. However, researchers have yet to discover the ideal biomaterial with properties suitable for human vocal fold application. The current systematic review employing PRISMA guidelines summarizes and discusses the available evidence related to outcome measures used to characterize novel biomaterials in the development phase. The literature search of related articles published within January 2010 to March 2021 was conducted using Scopus, Web of Science (WoS), Google Scholar and PubMed databases. The search identified 6240 potentially relevant records, which were screened and appraised to include 15 relevant articles based on the inclusion and exclusion criteria. The current study highlights that the characterization methods were inconsistent throughout the different studies. While rheologic outcome measures (viscosity, elasticity and shear) were most widely utilized, there appear to be no target or reference values. Outcome measures such as cellular response and biodegradation should be prioritized as they could mitigate the clinical drawbacks of currently available biomaterials. The review suggests future studies to prioritize characterization of the viscoelasticity (to improve voice outcomes), inflammatory response (to reduce side effects) and biodegradation (to improve longevity) profiles of newly developed biomaterials.

Dysphagia Severity and Outcomes Following Iatrogenic High Vagal Nerve Injury

OBJECTIVE

To examine severity of dysphagia and outcomes following iatrogenic high vagal nerve injury.

METHODS

Retrospective chart review of all patients with iatrogenic high vagal nerve injury that were seen at a tertiary referral center from 2012 to 2020.

RESULTS

Of 1304 patients who met criteria for initial screening, 18 met all inclusion criteria. All 18 required intervention to address postoperative dysphagia. Eleven required enteral feeding tubes with 7 eventually able to advance to exclusively per oral diets. Fourteen underwent vocal fold injection and 6 underwent laryngeal framework surgery. Sixteen pursued swallowing therapy with speech language pathology. Patients lost a mean of 8.6 kg of weight in the 6 months following the injury. Swallowing function on the Functional Outcome Swallowing Scale (FOSS) and Functional Oral Intake Scale (FOIS) was 4.4 and 2.4 respectively immediately following the injury and improved to 1.9 and 5.3 at the last follow-up. No patients had complete return of normal swallowing function at last follow up.

CONCLUSION

Iatrogenic high vagal injury causes significant lasting dysphagia which improves with intervention but does not completely resolve. Interventions such as vocal fold injection, medialization laryngoplasty, cricopharyngeal myotomy, or swallowing therapy may be required to reestablish safe swallowing in these patients.

Effects of Ultrasound-Guided Bilateral Cervical Plexus Block Combined with General Anesthesia in Patients Undergoing Total Parathyroidectomy and Partial Gland Autotransplantation Surgery

Background

The aim of this study is to evaluate the effect of ultrasound-guided bilateral cervical plexus block on general anesthesia, postoperative analgesia, and surgical outcomes in patients undergoing total parathyroidectomy with autotransplantation.

Patients and Methods

Forty-eight ASA III–IV patients with hyperparathyroidism secondary to renal failure were included: 24 patients received ultrasound-guided bilateral superficial and deep cervical plexus block combined with general anesthesia (group A), and 24 patients received general anesthesia alone (group B). Postoperative patient-controlled intravenous analgesia was provided with sufentanil 2 μg/kg. The primary outcome is the postoperative pain scores. Secondary outcomes include intraoperative remifentanil dosage, changes in hemodynamics, extubation time, and sufentanil consumption. Surgical outcomes regarding calcium, phosphorus and parathormone values were also noted.

Results

The patients in group A required less remifentanil than group B (2.56±0.92mg vs 3.38±0.84mg, P=0.002) and lower VAS scores at 1, 3, 10, 24, and 48h postoperatively (P < 0.001). While the systolic blood pressure in group A patients was significantly greater than that in group B at T3 (immediately after extubation, [138.33±11.36 vs 129.08±17.06 mmHg; P=0.032]), heart rates in group A were lower than in group B at 1 min before induction (T1 [89.46 ± 9.14 vs 96.71±14.19, P=0.042]) and 1 min after intubation (T2 [70.08 ± 5.35 vs 79.25 ± 11.81, P=0.002]). The extubation time in group A was shorter than that in group B (P < 0.001). There was no difference in calcium, phosphorus and parathormone values, nor in sufentanil consumption between the groups.

Conclusion

Ultrasound-guided bilateral superficial and deep cervical plexus block combined with general anesthesia for TPTA is an effective strategy to improve anesthesia management and achieve better postoperative analgesia, and has no impact on surgical outcomes.

Thyroidectomy in Pediatric Patients with Graves' Disease: A Systematic Review of Postoperative Morbidity

BACKGROUND

Graves' disease (GD) is the most common cause of hyperthyroidism. In children, the overall relapse frequency after treatment with antithyroid drugs is high. Therefore, many pediatric GD patients eventually require thyroidectomy as definitive treatment. However, the postoperative complications of thyroidectomy in pediatric GD patients are poorly reported.

OBJECTIVE

To identify the frequency of short- and long-term postoperative morbidities after thyroidectomy in pediatric GD patients.

METHODS

A systematic review of the literature (PubMed and Embase) was performed to identify studies reporting short- and long-term postoperative morbidities after thyroidectomy in pediatric GD patients according to the PRISMA guidelines.

RESULTS

Twenty-two mainly retrospective cohort studies were included in this review evaluating short- and long-term morbidities in 1,424 children and adolescents. The frequency of transient hypocalcemia was 22.2% (269/1,210), with a range of 5.0-50.0%. The frequency of permanent hypocalcemia was 2.5% (36/1,424), with a range of 0-20.0%. Two studies reported high frequencies of permanent hypocalcemia, 20.0 (6/30) and 17.4% (9/52), respectively. The 20% frequency could be explained by low-volume surgeons in poorly controlled GD patients. Only 21 cases of permanent hypocalcemia were reported in the 1,342 patients included in the other 20 studies (1.6%). Transient and permanent recurrent laryngeal nerve injury were reported less frequently, with frequencies between 0-20.0 and 0-7.1%, respectively. Infection, hemorrhage/hematoma, and keloid development were only rarely reported as postoperative complications.

CONCLUSION

The results of this systematic review suggest that thyroidectomy is a safe treatment option for pediatric GD patients. The minority of patients will experience transient and benign morbidities, with hypocalcemia being the most common transient postoperative morbidity. Permanent postoperative morbidities are relatively rare.

The Impact of Coexistent Hashimoto's Thyroiditis on Central Compartment Lymph Node Metastasis in Papillary Thyroid Carcinoma

BACKGROUND

Hashimoto's thyroiditis (HT) is the most prevalent inflammatory disorder of the thyroid gland. Current studies have reported the coexistence rate between HT and papillary thyroid carcinoma (PTC) is quite high. The objective of this study was to evaluate the impact of HT on the predictive factors of central compartment lymph node metastasis (CLNM) in PTC.

METHODS

A retrospective investigation was performed on PTC patients. They were subclassified into HT and non-HT groups. The results of preoperative neck ultrasound (US) examinations were reviewed. The clinical characteristics and the predictive value for CLNM were explored and compared between the two groups.

RESULTS

A total of 756 patients were included in this study. There were more female patients (86.1%) in the PTC coexistent with the HT group than non-HT group. The patients with HT group had higher preoperative serum level of TSH. There was statistically significant difference between the HT patients and non-HT patients in nodular vascularization. Univariate and multivariate analyses showed that male, age ≤45 years old, tumor diameter >1 cm, and presence of suspicious central compartment lymph node on US, irregular nodular shape, multifocal carcinoma were independent predictive factors of CLNM in PTC patients. It was showed that male, age ≤45 years old, tumor diameter >1 cm, multifocality, and presence of suspicious central lymph node on US were risk factors for CLNM in non-HT patients. Only tumor diameter >1 cm and presence of suspicious central lymph node on US were independently correlated with CLNM in HT patients. The sensitivity of the multivariate model was 63.5%, and specificity was 88.9% for prediction CLNM in HT patients. For non-HT patients, the AUC was 80.6%, the sensitivity of the multivariate model was 64.5%, and specificity was 85.2.

CONCLUSION

PTC combined with HT is more common in women, and TSH level in HT group is higher than that in patients with PTC alone. Regardless of that HT is not a related risk factor of CLNM in PTC, our result suggested that different predictive systems should be used for HT and non-HT patients respectively to have a more accurate evaluation of CLNM in clinic.

Immediate Intraoperative Repair of the Recurrent Laryngeal Nerve in Thyroid Surgery

OBJECTIVES

Recurrent laryngeal nerve (RLN) injury is a recognized risk during thyroid and parathyroid surgery and can result in significant morbidity. The aim of this review paper is to consider the optimal approach to the immediate intraoperative repair of the RLN during thyroid surgery.

METHODS

A PubMed literature search was performed from inception to June 2020 using the following search strategy: immediate repair or repair recurrent laryngeal nerve, repair or reinnervation recurrent laryngeal nerve and immediate neurorraphy or neurorraphy recurrent laryngeal nerve.

RESULTS

Methods of immediate intraoperative repair of the RLN include direct end-to-end anastomosis, free nerve graft anastomosis, ansa cervicalis to RLN anastomosis, vagus to RLN anastomosis, and primary interposition graft. Techniques of nerve repair include micro-suturing, use of fibrin glue, and nerve grafting. Direct micro-suture is preferable when the defect can be repaired without tension. Fibrin glue has also been proposed for nerve repair but has been criticized for its toxicity, excessive slow reabsorption, and the risk of inflammatory reaction in the peripheral tissues. When the proximal stump of the RLN cannot be used, grafting could be done using transverse cervical nerve, supraclavicular nerve, vagus nerve, or ansa cervicalis.

CONCLUSIONS

Current evidence is low-level; however, it suggests that when the RLN has been severed, avulsed, or sacrificed during thyroid surgery it should be repaired intraoperatively. The immediate repair has on balance more advantages than disadvantages and should be considered whenever possible. This should enable the maintenance of vocal cord tone, better and prompter voice recovery and avoidance of aspiration. Laryngoscope, 131:1429-1435, 2021.

Current landscape in motoneuron regeneration and reconstruction for motor cranial nerve injuries

The intricate anatomy and physiology of cranial nerves have inspired clinicians and scientists to study their roles in the nervous system. Damage to motor cranial nerves may result from a variety of organic or iatrogenic insults and causes devastating functional impairment and disfigurement. Surgical innovations directed towards restoring function to injured motor cranial nerves and their associated organs have evolved to include nerve repair, grafting, substitution, and muscle transposition. In parallel with this progress, research on tissue-engineered constructs, development of bioelectrical interfaces, and modulation of the regenerative milieu through cellular, immunomodulatory, or neurotrophic mechanisms has proliferated to enhance the available repertoire of clinically applicable reconstructive options. Despite these advances, patients continue to suffer from functional limitations relating to inadequate cranial nerve regeneration, aberrant reinnervation, or incomplete recovery of neuromuscular function. These shortfalls have profound quality of life ramifications and provide an impetus to further elucidate mechanisms underlying cranial nerve denervation and to improve repair. In this review, we summarize the literature on reconstruction and regeneration of motor cranial nerves following various injury patterns. We focus on seven cranial nerves with predominantly efferent functions and highlight shared patterns of injuries and clinical manifestations. We also present an overview of the existing reconstructive approaches, from facial reanimation, laryngeal reinnervation, to variations of interposition nerve grafts for reconstruction. We discuss ongoing endeavors to promote nerve regeneration and to suppress aberrant reinnervation and the development of synkinesis. Insights from these studies will shed light on recent progress and new horizons in understanding the biomechanics of peripheral nerve neurobiology, with emphasis on promising strategies for optimizing neural regeneration and identifying future directions in the field of motor cranial neuron research.

Immediate Ansa Cervicalis-to-Recurrent Laryngeal Nerve Anastomosis for the Management of Recurrent Laryngeal Nerve Infiltration by a Differentiated Thyroid Carcinoma

OBJECTIVES

The optimal surgical approach to treat recurrent laryngeal nerve (RLN) infiltration by differentiated thyroid cancer (DTC) remains a subject of debate. This study explored the feasibility and efficiency of immediate ansa cervicalis nerve (ACN)-to-RLN anastomosis for the management of RLN infiltration by DTC.

MATERIAL AND METHODS

Fifty-three patients who underwent immediate ACN-to-RLN anastomosis during DTC extirpation were enrolled in the present study. Thirty-seven cases presented with unilateral vocal cord paralysis before the operation (Group A), and another 16 patients presented with normal vocal cord mobility preoperatively (Group B). Multidimensional assessments, videostroboscopy, voice assessment, and laryngeal electromyography (LEMG) were performed preoperatively and postoperatively.

RESULTS

All videostroboscopy, voice assessment and LEMG parameters in Group A deteriorated 1 month after the operation and improved 1 year after the operation compared with preoperative data. In Group B, all parameters 1 year after the operation improved significantly compared with the corresponding parameters 1 month after the operation. LEMG in Group A and B provided substantial evidence for the maturation of neural regeneration from ACN and demonstrated that the laryngeal muscles were reinnervated successfully by this procedure.

CONCLUSIONS

If the RLN is infiltrated by DTC, immediate ACN-to-RLN anastomosis during complete excision of DTC could restore satisfactory phonatory function and does not compromise oncological radicality.

Early detection of recurrent laryngeal nerve damage using intraoperative nerve monitoring during thyroidectomy

Objective

This study aimed to investigate risk factors for early recurrent laryngeal nerve (RLN) damage during thyroid surgery with intraoperative nerve monitoring (IONM) technology to avoid RLN damage during surgery.

Methods

Data were retrospectively collected from 93 patients who underwent thyroidectomy at Beijing Hospital. All operations were performed by the same surgeon. A four-step procedure of IONM was used during the operation to determine the amplitude and latency of the RLN.

Results

The majority (51.6%) of patients who underwent surgery had thyroid carcinoma. Lymphadenectomy was carried out in 55 (59.1%) patients. A strong association was observed between temporary injury of the RLN and the extent of resection. The risk of temporary injury of the RLN during total thyroidectomy was three times that during right thyroid lobectomy (odds ratio = 3.13). The results of left lobectomy were also different from those of right lobectomy because the RLN was more likely to be damaged during left lobectomy.

Conclusions

Assessment of the amplitude and latency of the RLN can help to assess the integrity of the RLN. The extent of resection affects the functional integrity of the RLN.

Main branch of ACN-to-RLN for management of laryngospasm due to unilateral vocal cord paralysis

OBJECTIVES/HYPOTHESIS

This study explored the feasibility and efficiency of main branch of ansa cervicalis nerve (ACN)-to-recurrent laryngeal nerve (RLN) anastomosis for management of paroxysmal laryngospasm due to unilateral vocal cord paralysis (UVCP).

METHODS

Thirteen patients who underwent main branch of ACN-to-RLN anastomosis for management of paroxysmal laryngospasm due to UVCP were enrolled in the present study. Multidimensional assessments, including videostroboscopy, voice assessment, and laryngeal electromyography (LEMG), were performed preoperatively and postoperatively.

RESULTS

This series was limited to UVCP with iatrogenic causes, including thyroidectomy, cervical spine surgery, and thoracic surgery. After main branch of ACN-to-RLN anastomosis, all cases showed significant airway improvement, and laryngospasm was completely abolished in 92.3% (12 of 13) of cases. Videostroboscopy showed that the bulging and paradoxical adduction of the affected vocal cord during a sniff were abolished immediately after operation, and there was no significant difference in vocal fold position or glottal closure before versus after the operation. LEMG showed that the postoperative recruitment and amplitude of voluntary motor unit potential in the affected thyroarytenoid muscle during a sniff were significantly decreased compared to preoperative values, and postoperative recruitment showed significant improvement during phonation compared to that preoperatively. Voice assessment showed that there were no significant differences in overall grade, roughness, breathiness, jitter (local), shimmer (local), noise-to-harmonics ratio, or maximum phonation time after the operation compared to the preoperative values.

CONCLUSIONS

Main branch of ACN-to-RLN anastomosis could have long-lasting efficacy in the management of paroxysmal laryngospasm due to UVCP, with no apparent compromise of voice quality.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:2412-2419, 2020.

The Nerve to Thyrohyoid Muscle as a Novel Donor Nerve for Laryngeal Reinnervation

Objectives:

Recurrent laryngeal nerve (RLN) injury may be a consequence of surgical procedures of the skull base, neck, and chest, with adverse consequences to function and quality of life. Laryngeal reinnervation offers a potentially stable improvement in vocal fold position and tone. The classic donor nerve is the ansa cervicalis, but is not always available due to damage or sacrifice during previous neck surgeries. Our objective was to introduce the nerve to the thyrohyoid (TH) muscle as an alternate donor nerve for reinnervation, which has not previously been described.

Methods:

Case series of two patients using the TH nerve for laryngeal reinnervation after RLN injury, with description of surgical harvest.

Results:

Follow-up results are available for 10 months (one patient) and 3 years (one patient) demonstrating both subjective and objective improvement in function. GRBAS scores were reduced. Maximal phonation time was improved. Patient rating of voice was stable or improved postoperatively. One patient described significant preoperative dyspnea which was significantly improved postoperatively, from a score of 24 to 10 out of 40 on the dyspnea handicap index. VHI was improved in one patient, but scores elevated in the other, despite a change from “moderately severe impairment” to “normal voice” subjectively. Neither patient experienced significant complications from the procedure.

Conclusion:

Laryngeal reinnervation procedures provide good outcomes in pediatric patients. When ansa cervicalis is not available as a donor nerve, the nerve to TH provides a reasonable alternative.

Ipsilateral nonrecurrent laryngeal nerve palsy and delayed palsy of the contralateral recurrent laryngeal nerve in a case of third-time reoperative thyroid surgery

The occurrence of nonrecurrent laryngeal nerve and delayed nerve palsy of the contralateral nerve occurring simultaneously has never been described. A 67-year-old woman underwent reoperative completion thyroidectomy for enlarging thyroid nodules with recurrent hyperthyroidism and obstructive symptoms. Preoperative computed tomography of the neck showed a large compressive goitre with an aberrant right subclavian artery. At surgery, a type 1 nonrecurrent laryngeal nerve was found and inadvertently transected due to dense adhesions. It was repaired with ansa cervicalis graft. A fully preserved and functional recurrent laryngeal nerve was seen on the contralateral side at the end of surgery. However, the patient developed a delayed palsy on day 4 of the recurrent laryngeal nerve requiring a tracheostomy. Following successful speech and swallowing therapy, the patient was decannulated with good phonation and recovery of the left cord. Patients are at risk of bilateral nerve injury and late onset palsy in reoperative thyroid surgery. Management can be challenging and should be recognised to ensure appropriate therapy.

Risk Assessment and Hydrodissection Technique for Radiofrequency Ablation of Thyroid Benign Nodules

Purpose: This retrospective study aimed to explore the importance of risk assessment and hydrodissection pre-treatment for radiofrequency ablation of thyroid nodules and initially establish the concept of thyroid nodule risk assessment and the corresponding ablation norms.

Method: Based on the specific location of thyroid nodules, risk assessment and the corresponding preventive measures for thyroid ablation were established. During the period of 2015.10-2017.5, a total of 382 patients were enrolled to compare the safety and efficacy of the ablation for patients with or without risk assessment and the corresponding preventive measures. Statistical analysis encompassed Independent T test for continuous variables and Fisher's exact test/Chi-square test for categorical variables.

Result: Of all 382 patients, 188 patients underwent ablation with risk assessment and the corresponding preventive measures before ablation and 194 without, respectively. The patient characteristics, risk grading, ablation time, thyroid function after ablation and the complete ablation rate showed no statistical differences exsisted between two groups (P>0.05). The complication in very high risk nodules was avoided in the group of patients with risk assessment and preventive measures before ablation.

Conclusion: It is a very safe and effective way to carry out radiofrequency ablation after pre-treatment of thyroid nodules by hydrodissection technique according to risk assessment. It will provide clinicians with greater help in the ablation treatment of thyroid nodules, and improve the safety of the thyroid ablation.

Ultrasound-guided percutaneous microwave ablation versus surgery for papillary thyroid microcarcinoma

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) has high incidence and low disease-specific mortality. However, active surveillance is not accepted by most patients owing to high physical or psychological pressures. The emergence of ablation technologies is supplanting traditional surgery. Our goal was to compare the clinical outcomes of microwave ablation (MWA) and surgery for T1aN0M0 PTMC.

METHODS

A total of 92 consecutive patients with T1aN0M0 PTMC were studied retrospectively. Forty-six patients had been treated with MWA, and the other 46 had undergone surgery. MWA was performed using extensive ablation extending from the nodule's lower pole to the upper pole. Surgery was performed by total thyroidectomy or thyroid lobectomy. We compared the two groups in terms of mean length of stay, cost, mean blood loss, surgical incision, operating room (OR) time, quality of life (QOL) assessment, complications, and therapeutic efficacy over a follow-up period of 42 months.

RESULTS

The mean length of stay, cost, mean blood loss, surgical incisions, OR time, and complications in the MWA group were significantly lower than those of the surgery group. The QOL after MWA was higher than it was after surgery. The nodule volume decreased significantly from 53.61 ± 48.43 mm³ to 4.84 ± 6.55 mm³ (p < .001) at the 42-month follow-up, exhibiting a percentage volume reduction of 81.33 ± 36.87%. No recurrence or metastasis occurred in either group during the follow-up period.

CONCLUSIONS

MWA may be considered a minimally invasive alternative to surgery for solitary T1aN0M0 PTMC with low incidence of complications and good therapeutic effect.

Olfactory-ensheathing cells promote physiological repair of injured recurrent laryngeal nerves and functional recovery of glottises in dogs

The aim of this study was to investigate whether the transplantation of olfactory-ensheathing cells (OECs) could physiologically repair severely injured recurrent laryngeal nerve (RLN) in dogs. Adult Beagle dogs were surgically introduced with a 10-mm defect in the left RLN and transplanted with a nerve guide (NEUROLAC) containing dog olfactory mucosa-olfactory-ensheathing cells (OM-OECs) in matrigel. The effects of OM-OECs on the morphology, histology, and electrophysiology of the injured RLNs, glottis movement, and voice acoustics were comparatively studied. Two months after transplantation, the normal dogs (group N) had intact left RLNs that contained axons well organized as bundles, transmitted action potentials of high amplitudes without latent phases, and modulated glottis movement to produce normal voices. The RLN-damaged dogs transplanted with OM-OECs (group CTT) had pieces of nerves regenerated in the place of the defects, which contained fewer axons scattered in the internal nerve membrane and wrapped peripherally by the connective tissue, prevented the distal trunk of the defected RLN from shrinking, transmitted action potentials of lower amplitudes with latent phases, and modulated a slightly impaired glottis movement to produce voices with slight differences compared to the N dogs. The RLN-damaged dogs without OM-OECs (group NC) had no nerves generated at the defective or the damaged area, leading to a shrinkage in the enervated distal nerve trunks; a blockage in nerve pulse transit; a paralysis of the left vocal cords; an impaired glottis movement; and abnormal voices. Transplantation of OM-OECs promoted nerve regeneration, and the recoveries of glottises and voices in dogs with RLN injury.

A long-term comparative prospective study between reinnervation and injection laryngoplasty

OBJECTIVES

This study compared and assessed long-term voice outcomes when thyroidectomy-related unilateral vocal fold paralysis (VFP) was managed using injection laryngoplasty (IL) and recurrent laryngeal nerve reinnervation (RLNR).

STUDY DESIGN

Prospective clinical study.

METHODS

A prospective clinical trial was performed from March 2005 to January 2016 at Soonchunhyang University Bucheon Hospital (Bucheon, South Korea). Nineteen patients who underwent ansa cervicalis to RLNR or direct reinnervation, and 43 patients who underwent IL to treat thyroidectomy-related unilateral VFP, were enrolled.

RESULTS

All voice parameters exhibited statistically significant improvement 12 months post-IL, which persisted for 24 and 36 months (P < 0.05). However, at 36 months post-IL, some voice parameters had deteriorated relative to the values at 24 months post-IL. After RLNR, all voice parameters exhibited statistically significant improvement after 12 months, and the improvements remained stable until 36 months postsurgery without deterioration of voice parameters (P < 0.05). At 36 months, RLNR provided better voice results than IL (P < 0.05).

CONCLUSION

Both RLNR and IL yielded statistically significant voice improvements at 36 months postoperatively. However, after 36 months, RLNR provided better results than IL.

LEVEL OF EVIDENCE

3. Laryngoscope, 1893-1897, 2018.