Recovery of laryngeal function after intraoperative injury to the recurrent laryngeal nerve

Hemithyroidectomy, does the indication influence the outcome?

PURPOSE

Hemithyroidectomies are mainly performed for two indications, either therapeutically to relieve compression symptoms or diagnostically for suspicious nodule(s). In case of the latter, one could consider the approach to be rather extensive since the majority of patients have no symptoms and will have benign disease. The aim of this study is to investigate the complication rates of diagnostic hemithyroidectomy and to compare it with the complication rates of compressive symptoms hemithyroidectomy.

METHODS

Data from patients who had undergone hemithyroidectomy either for compression symptoms or for excluding malignancy were extracted from a well-established Scandinavian quality register (SQRTPA). The following complications were analyzed: bleedings, wound infections, and paresis of the recurrent laryngeal nerve (RLN). Risk factors for these complications were examined by univariable and multivariable logistic regression.

RESULTS

A total of 9677 patients were included, 3871 (40%) underwent surgery to exclude malignancy and 5806 (60%) due to compression symptoms. In the multivariable analysis, the totally excised thyroid weight was an independent risk factor for bleeding. Permanent (6-12 months after the operation) RLN paresis were less common in the excluding malignancy group (p = 0.03).

CONCLUSION

A range of factors interfere and contribute to bleeding, wound infections, and RLN paresis after hemithyroidectomy. In this observational study based on a Scandinavian quality register, the indication "excluding malignancy" for hemithyroidectomy is associated with less permanent RLN paresis than the indication "compression symptoms." Thus, patients undergoing diagnostic hemithyroidectomy can be reassured that this procedure is a safe surgical procedure and does not entail an unjustified risk.

Effects of Unilateral Vagotomy on LPS-Induced Aspiration Pneumonia in Mice

Respiratory-related dysphagia and aspiration pneumonia can be attributed to multiple causes. However, reproduction of multiple factor-related respiratory distress and aspiration pneumonia in a single animal model is challenging. To validate animals with vagal nerve palsy as novel models for severe aspiration pneumonia associated with respiratory distress, we investigated the effects of unilateral vagotomy on the swallowing function and severity of pneumonia after forced aspiration in mice. Unilateral vagotomy was performed in C57BL6 male mice that subsequently underwent evaluation of swallowing function by videofluoroscopic swallow study (VFSS) and histological assessments for aspiration pneumonia induced by lipopolysaccharide (LPS). VFSS examinations demonstrated that unilateral vagotomy did not cause apparent aspiration in mice, but it resulted in a significant loss of body weight (BW) due to decreased oral intake. In addition, when aspiration pneumonia was induced by forced administration of LPS, significantly prolonged BW loss and severe infiltration of inflammatory cells associated with aspiration pneumonia were observed in the mice that underwent unilateral vagotomy. In conclusion, the vagotomized mice showed appropriate characteristics as a model of aspiration pneumonia caused by multiple factors, including the paralysis of vocal fold movement and respiratory distress. This model can help elucidate the pathogenesis of aspiration pneumonia and the treatment methods for the respiration-compromised model.

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.

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.

Guidelines for the Management of Unilateral Vocal Fold Paralysis From the Korean Society of Laryngology, Phoniatrics and Logopedics

The Korean Society of Laryngology, Phoniatrics and Logopedics appointed a task force to establish clinical practice guidelines for the management of unilateral vocal fold paralysis (UVFP). These guidelines cover a comprehensive range of management-related factors, including the diagnosis and treatment of UVFP, and provide in-depth information based on current, up-to-date knowledge. Detailed evidence profiles are provided for each recommendation. The CORE databases, including OVID Medline, Embase, the Cochrane Library, and KoreaMed, were searched to identify all relevant papers, using a predefined search strategy. When insufficient evidence existed, expert opinions and Delphi questionnaires were used to fill the evidence gap. The committee developed 16 evidence-based recommendations in six categories: initial evaluation (R1–4), spontaneous recovery (R5), medical treatment (R6), surgical treatment (R7–14), voice therapy (R15), and aspiration prevention (R16). The goal of these guidelines is to assist general otolaryngologists and speech-language pathologists who are primarily responsible for treating patients with UVFP. These guidelines are also intended to facilitate understanding of the condition among other health-care providers, including primary care physicians, nurses, and policy-makers.

Analysis of post-operative efficacy and pharyngeal fistula healing in patients with laryngeal cancer treated with post-operative enteral nutrition support nursing combined with early oral feeding

The present study aimed to analyze the effects of post-operative enteral nutrition support nursing combined with early oral feeding on post-operative efficacy and pharyngeal fistula (PF) healing in patients with laryngeal cancer (LC). A retrospective analysis of 133 patients with LC, who underwent laryngectomy between May 2014 and September 2016, was conducted. Of these patients, 61 patients (control group) were treated with enteral nutrition support nursing combined with nasogastric feeding, and 72 patients (observation group) were treated with enteral nutrition support nursing combined with early oral feeding. Levels of serum albumin (ALB), pre-albumin (PA), hemoglobin (Hb) and the lymphocyte count (LYM) were compared before and after surgery (7 and 14th post-operative days). The post-operative weight, upper arm muscle circumference (UAMC), triceps skinfold (TSF), post-operative infection, adverse reactions and PF healing were also measured. No differences were observed between the control and observation groups before surgery (all P>0.05). ALB, Hb, PA and LYM were significantly decreased in the control group on the 7 and 14th days post-operatively compared with those in the observation group (all P<0.05). Five patients in the control group presented with PF during treatment, and seven patients in the observation group suffered from PF after surgery. No difference in the average healing time of PF, number of patients with post-operative infection and adverse reactions were observed between the two groups (all P>0.05). The weight and UAMC in the observation group, 14 days post-operatively, were significantly higher than those before surgery in the same patients and in the control group (all P<0.05), whereas no difference in TSF (P>0.05) was observed. No differences in weight, UAMC and TSF were revealed in the control group before surgery and on the 14th day post-operatively (all P>0.05). Thus, post-operative enteral nutrition support nursing combined with early oral feeding resulted in significant improvement in the post-operative efficacy of patients with LC and had no effect on PF healing.

Recurrent laryngeal nerve transection in mice results in translational upper airway dysfunction

The recurrent laryngeal nerve (RLN) is responsible for normal vocal-fold (VF) movement, and is at risk for iatrogenic injury during anterior neck surgical procedures in human patients. Injury, resulting in VF paralysis, may contribute to subsequent swallowing, voice, and respiratory dysfunction. Unfortunately, treatment for RLN injury does little to restore physiologic function of the VFs. Thus, we sought to create a mouse model with translational functional outcomes to further investigate RLN regeneration and potential therapeutic interventions. To do so, we performed ventral neck surgery in 21 C57BL/6J male mice, divided into two groups: Unilateral RLN Transection (n = 11) and Sham Injury (n = 10). Mice underwent behavioral assays to determine upper airway function at multiple time points prior to and following surgery. Transoral endoscopy, videofluoroscopy, ultrasonic vocalizations, and whole-body plethysmography were used to assess VF motion, swallow function, vocal function, and respiratory function, respectively. Affected outcome metrics, such as VF motion correlation, intervocalization interval, and peak inspiratory flow were identified to increase the translational potential of this model. Additionally, immunohistochemistry was used to investigate neuronal cell death in the nucleus ambiguus. Results revealed that RLN transection created ipsilateral VF paralysis that did not recover by 13 weeks postsurgery. Furthermore, there was evidence of significant vocal and respiratory dysfunction in the RLN transection group, but not the sham injury group. No significant differences in swallow function or neuronal cell death were found between the two groups. In conclusion, our mouse model of RLN injury provides several novel functional outcome measures to increase the translational potential of findings in preclinical animal studies. We will use this model and behavioral assays to assess various treatment options in future studies.

A Surgical Mouse Model for Advancing Laryngeal Nerve Regeneration Strategies

Iatrogenic recurrent laryngeal nerve (RLN) injury is a morbid complication of anterior neck surgical procedures. Existing treatments are predominantly symptomatic, ranging from behavioral therapy to a variety of surgical approaches. Though laryngeal reinnervation strategies often provide muscle tone to the paralyzed vocal fold (VF), which may improve outcomes, there is no clinical intervention that reliably restores true physiologic VF movement. Moreover, existing interventions neglect the full cascade of molecular events that affect the entire neuromuscular pathway after RLN injury, including the intrinsic laryngeal muscles, synaptic connections within the central nervous system, and laryngeal nerve anastomoses. Systematic investigations of this pathway are essential to develop better RLN regenerative strategies. Our aim was to develop a translational mouse model for this purpose, which will permit longitudinal investigations of the pathophysiology of iatrogenic RLN injury and potential therapeutic interventions. C57BL/6J mice were divided into four surgical transection groups (unilateral RLN, n = 10; bilateral RLN, n = 2; unilateral SLN, n = 10; bilateral SLN, n = 10) and a sham surgical group (n = 10). Miniaturized transoral laryngoscopy was used to assess VF mobility over time, and swallowing was assessed using serial videofluoroscopy. Histological assays were conducted 3 months post-surgery for anatomical investigation of the larynx and laryngeal nerves. Eight additional mice underwent unilateral RLN crush injury, half of which received intraoperative vagal nerve stimulation (iVNS). These 8 mice underwent weekly transoral laryngoscopy to investigate VF recovery patterns. Unilateral RLN injury resulted in chronic VF immobility but only acute dysphagia. Bilateral RLN injury caused intraoperative asphyxiation and death. VF mobility was unaffected by SLN transection (unilateral or bilateral), and dysphagia (transient) was evident only after bilateral SLN transection. The sham surgery group retained normal VF mobility and swallow function. Mice that underwent RLN crush injury and iVNS treatment demonstrated accelerated and improved VF recovery. We successfully developed a mouse model of iatrogenic RLN injury with impaired VF mobility and swallowing function that can serve as a clinically relevant platform to develop translational neuroregenerative strategies for RLN injury.

Long-term quality of voice is usually acceptable after initial hoarseness caused by a thyroidectomy or a parathyroidectomy

Background

Vocal cord (VC) palsy following a thyroidectomy or parathyroidectomy can result in significant morbidity for the patient. We aimed to investigate the incidence of VC palsy in a tertiary referral Institution, track the management of these cases and record the long-term outcomes and VC recovery rates.

Methods

Retrospective review of all thyroidectomy/parathyroidectomy operations performed over 11 years. Patients with an unequivocal hoarse voice postoperatively were included. We analysed the patient's clinical characteristics and voice outcomes, operative, pathology and laryngoscopy reports during their follow-up.

Results

Ten patients fitted the inclusion criteria and were analysed. Median age at date of operation was 47.5 years (range, 16-81 years) and the M:F ratio was 1:2.3 (M:3, F:7). The median FU was 62.5 months (range, 12-144 months). The median hospital stay was 1.5 days (range, 1-87 days). There were 7 recurrent laryngeal nerve (RLN) injuries by manipulation, 1 case of RLN resection, 1 inadvertent division (with primary nerve repair) and 1 RLN was shaved off the thyroid. Long-term voice outcomes for the 7 patients with an RLN manipulation injury were: 3/7 patients had normal voice, 3/7 had moderate hoarseness and 1/7 had long-term hoarseness. The long-term voice outcome of the patient with RLN shaving off the thyroid gland was excellent while the 2 remaining patients (RLN resection and inadvertent division) needed 12 and 18 months respectively to achieve a normal quality of voice. Four out of the 10 patients had permanent VC palsy in the long-term and their voice outcomes varied: 1 patient had a normal voice, 2 patients had moderate hoarseness and 1 patient had persistent hoarseness. Only 1/10 patients did not show any voice improvement after 12 months.

Conclusions

In the vast majority of cases post-operative hoarseness due to RLN palsy improves in the long-term, albeit voice may not return completely to normal.

TOTAL THYROIDECTOMY FOR MALIGNANCY - IS CENTRAL NECK DISSECTION A RISK FACTOR FOR RECURRENT NERVE INJURY AND POSTOPERATIVE HYPOCALCEMIA? A TERTIARY CENTER EXPERIENCE IN ROMANIA

Introduction

Surgery for thyroid cancer carries a higher risk of morbidity given the region's complicated anatomy, the setting of malignancy and extent of the surgery.

Aim

To investigate the rate of complications related to the recurrent nerve and parathyroid glands lesions in patients with thyroid carcinoma that undergo thyroid surgery and lymph node dissection.

Patients and Methods

The data of 71 patients who underwent total thyroidectomy and 19 patients who underwent total thyroidectomy and central neck dissection with various associated neck dissection techniques were investigated using appropriate statistical tests.

Results

As expected, the rate of recurrent nerve injury observed in the neck dissection group was higher than in the total thyroidectomy group (15.7% vs. 2.8%, p=0.05). As for postoperative hypocalcemia, the rate observed in the neck dissection group, both for postoperative day 1 (p<0.0001) and day 30 (p=0.0003) was higher than in the total thyroidectomy group (68.4% vs. 19.7% postoperative day 1, 31.5% vs. 4.2% postoperative day 30).

Conclusions

The risk of morbidity concerning the recurrent nerve injury and postoperative hypoparathyroidism increases with the extent of surgery. Extensive surgery may achieve proper oncologic outcomes but increases the risk of postoperative morbidity and decreases quality of life. In deciding for extensive surgery, both patient and medical team need to understand these risks.

Automated Quantification of Vocal Fold Motion in a Recurrent Laryngeal Nerve Injury Mouse Model

OBJECTIVES/HYPOTHESIS

The goal of this study was to objectively examine vocal fold (VF) motion dynamics after iatrogenic recurrent laryngeal nerve (RLN) injury in a mouse surgical model. Furthermore, we sought to identify a method of inducing injury with a consistent recovery pattern from which we can begin to evaluate spontaneous recovery and test therapeutic interventions.

STUDY DESIGN

Animal model.

METHODS

The right RLN in C57BL/6J mice was crushed for 30 seconds using an aneurysm clip with 1.3-N closing force. Transoral laryngoscopy enabled visualization of VF movement prior to surgery, immediately post-crush, and at two endpoints: 3 days (n = 5) and 2 weeks (n = 5). VF motion was quantified with our custom motion-analysis software. At each endpoint, RLN samples were collected for transmission electron microscopy for correlation with VF motion dynamics.

RESULTS

Our VF tracking software permitted automated quantification of several measures of VF dynamics, such as range and frequency of motion. By 2 weeks post-injury, the frequency of VF movement on the right (injured) side equaled the left, yet range of motion only partially recovered. These objective outcome measures enabled detection of VF dysfunction that persisted at 2 weeks post-crush. Transmission electron microscopy images revealed RLN degeneration 3 days post-crush and partial regeneration at 2 weeks, consistent with functional results obtained with automated VF tracking.

CONCLUSIONS

Our motion-analysis software provides novel objective, quantitative, and repeatable metrics to detect and describe subtle VF dysfunction in mice that corresponds with underlying RLN degeneration and recovery. Adaptation of our tracking software for use with human patients is underway.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E247-E254, 2019.

Application of transoral continuous intraoperative neuromonitoring in natural orifice transluminal endoscopic surgery for thyroid disease: a preliminary study

BACKGROUND

The novel concept of continuous intraoperative neuromonitoring (Cont-IONM) through stimulation of the vagal nerve has been used in thyroidectomies to prevent imminent injury of the recurrent laryngeal nerve (RLN). This article reports on this technology and the results of using transoral Cont-IONM in natural orifice transluminal endoscopic surgery for thyroid disease.

METHODS

Cont-IONM of the RLN was achieved through automatic cyclical stimulation of the vagal nerve using a C2 monitor and delta stimulating electrode. During the operation, three vestibular incisions were made, and the stimulating electrode was transorally inserted, with its cable line lying outside the trocar. The vagal nerve was gently dissected, looped, and then enveloped by the electrode cuff. Electromyography (EMG) of the vocalis muscle was performed, and the alarm was set to activate when the EMG amplitude reduced by 50% and latency was prolonged by 10%. Demographic data and outcome variables, including incremental time required to achieve Cont-IONM, were obtained.

RESULTS

A total of 20 patients (28 nerves at risk) undergoing a transoral endoscopic thyroidectomy vestibular approach were enrolled in this study. All Cont-IONM procedures were successfully completed. In all patients, the stimulation was set at 0.7 milliamps every 1 s, and Cont-IONM use was unassociated with any untoward neural, cardiovascular, or gastrointestinal sequelae. On average, the ipsilateral Cont-IONM procedure required 10.33 ± 2.57 min to complete. Except for one instance, no significant problems occurred with electrode displacement. In one patient, a combined EMG event occurred, which improved after releasing the thyroid retractor, and the patient had no vocal cord paralysis postoperatively.

CONCLUSION

Cont-IONM is feasible and safe to use during transoral endoscopic thyroidectomies and may assist in the early detection of adverse EMG changes, thereby preventing paralysis of the RLNs.

Vocal fold mobility alteration reversed after thyroidectomy

The involvement of the inferior or recurrent laryngeal nerve (RLN) in mobility derangement of the vocal folds occurs more frequently due to thyroid malignancy invasion. Although uncommon, the same derangement, which is caused by benign thyroid entities, is also described and reverts to normality after a thyroidectomy in up to 89% of cases. In these cases, the pathogenesis of the vocal cord mobility disturbance is attributed to the direct compression of the RLN by massive thyroid enlargement. The authors describe three cases of patients presenting unilateral vocal cord palsy, which, before surgery, was diagnosed by laryngoscopy concomitantly with large and compressive goiter. Vocal fold mobility became normal after the thyroidectomy in all three cases. Therefore, it is noteworthy that these alterations may present reversibility after appropriate surgical treatment. An early surgical approach is recommended to reduce the nerve injury as much as possible; to preserve the integrity of both RLNs since the nerve function will be restored in some patients.

The Physiologic Impact of Unilateral Recurrent Laryngeal Nerve (RLN) Lesion on Infant Oropharyngeal and Esophageal Performance

Recurrent laryngeal nerve (RLN) injury in neonates, a complication of patent ductus arteriosus corrective surgery, leads to aspiration and swallowing complications. Severity of symptoms and prognosis for recovery are variable. We transected the RLN unilaterally in an infant mammalian animal model to characterize the degree and variability of dysphagia in a controlled experimental setting. We tested the hypotheses that (1) both airway protection and esophageal function would be compromised by lesion, (2) given our design, variability between multiple post-lesion trials would be minimal, and (3) variability among individuals would be minimal. Individuals' swallowing performance was assessed pre- and post-lesion using high speed VFSS. Aspiration was assessed using the Infant Mammalian Penetration-Aspiration Scale (IMPAS). Esophageal function was assessed using two measures devised for this study. Our results indicate that RLN lesion leads to increased frequency of aspiration, and increased esophageal dysfunction, with significant variation in these basic patterns at all levels. On average, aspiration worsened with time post-lesion. Within a single feeding sequence, the distribution of unsafe swallows varied. Individuals changed post-lesion either by increasing average IMPAS score, or by increasing variation in IMPAS score. Unilateral RLN transection resulted in dysphagia with both compromised airway protection and esophageal function. Despite consistent, experimentally controlled injury, significant variation in response to lesion remained. Aspiration following RLN lesion was due to more than unilateral vocal fold paralysis. We suggest that neurological variation underlies this pattern.