Is identification and dissection of the external laryngeal nerve necessary during thyroidectomy? A prospective study.

BACKGROUND: Compared to the recurrent laryngeal nerve, the EBSLN (or external laryngeal nerve) is less studied in terms of its course and relationship with the thyroid gland. This is a prospective intraoperative study designed to identify the anatomical variations of the EBSLN in relation to the IPC, the superior thyroid pedicle, and the point where the nerve crosses the STA. Additionally, the study aims to propose a technical procedure for its preservation. METHODS: We conducted a prospective study of 50 patients (total of 100 nerves) undergoing total thyroidectomy at the Department of Surgery 'B' in Ibn Sina Hospital, Rabat. Intraoperatively, the EBSLN was visually identified and preserved before ligating the superior thyroid vessels. Each nerve was categorized using established classification systems. RESULTS: The overall pooled EBSLN identification rate was 82%. Cernea type IIa (nerves crossing the STA less than 1 cm above the upper edge of the superior thyroid pole) and Friedman type II (nerves piercing the lower fibers of the IPC) were the most prevalent (64% and 44%, respectively). Kierner type IV (nerves crossing the branches of the STA immediately above the upper pole of the thyroid gland) was represented in 27% of cases. CONCLUSION: A better understanding of surgical anatomy of the neck allows for better results of thyroidectomy by preserving the external and recurrent laryngeal nerves.

Transection Of Sternothyroid Muscle Increases The Rate Of Exposure Of The External Branch Of The Superior Laryngeal Nerve During Thyroidectomy.

Objectives: To assess the benefits of transection of the sternothyroid muscle compared to conventional approach for detecting the external branch of the superior laryngeal nerve while dealing with the upper pole of the thyroid gland. METHODS: The randomised controlled clinical trial was conducted at Kafrelsheikh University Hospital, Egypt, from January 2021 to January 2022, and comprised patients who were eligible for total thyroidectomy and met the American Thyroid Association guidelines. They were randomised and divided into conventional approach group A and sternothyroid muscle transection approach group B. The rate of exposure of the external branch of the superior laryngeal nerve, injury, classification, operative time and voice outcomes at 2 weeks and 3 months post-intervention were noted in both the groups. Data was analysed using SPSS 22. RESULTS: Of the 102 patients, 50(49%) were in group A; 5(10%) males and 45(90%) females with mean age 40.48±12.58 years and mean body massindex 30.676±2.305. There were 52(51%) patientsin group B; 5(9.6%) males and 45(90.4%) females with mean age 39.67±11.60 years and mean body mass index 30.096±2.776. The rate of external branch of the superior laryngeal nerve identification was higher and the operative time was shorter in group B compared to group A (p=0.05). No significant difference was noted in terms of voice outcomes either at baseline or at any of the two follow-up points between the groups (p>0.05). CONCLUSIONS: The transection of sternothyroid muscle improved the rate of external branch of the superior laryngeal nerve exposure and preservation compared to the conventional technique during thyroidectomy.

Study on Microsurgical Anatomy of External Branch of Superior Laryngeal Nerve Related to Carotid Endarterectomy.

OBJECTIVE: To explore the methods of protecting the external branch of the superior laryngeal nerve during carotid endarterectomy through microsurgical anatomic study of the external branch of the superior laryngeal nerve in cadaveric specimens. METHODS: A total of 30 cadaveric specimens (60 sides) were dissected to measure the thickness of the external branch of the superior laryngeal nerve. A triangular area was exposed, bounded by the lower border of the digastric muscle superiorly, the medial edge of the sternocleidomastoid muscle laterally, and the upper border of the superior thyroid artery inferiorly. The probability of the occurrence of the external branch of the superior laryngeal nerve in this area was observed and recorded. The distance among the midpoint of the external branch of the superior laryngeal nerve in this area with the tip of the mastoid process and the angle of the mandible as well as the bifurcation of the common carotid artery was measured and recorded. RESULTS: Among 30 specimens of cadaveric heads (60 sides) examined 53 external branches of the superior laryngeal nerve were observed while 7 were absent. Of the 53 branches observed, 5 were located outside the anatomic triangle region mentioned above, while the remaining 48 branches were located within the anatomic triangle region with a probability of ~80%. The thickness of the midpoint of the external branches of the superior laryngeal nerve within the anatomic triangle region was 0.93 mm (0.72-1.15 mm [±0.83 SD]), located 0.34 cm [-1.62-2.43 cm (±0.96 SD)] posterior to the angle of the mandible, 1.28 cm (-1.33 to 3.42 cm (±0.93 SD)] inferiorly; 2.84 cm (0.51-5.14 cm±1.09 SD) anterior to the tip of the mastoid process, 4.51 cm (2.82-6.39 cm±0.76 SD) inferiorly; 1.64 cm [0.57-3.78 cm (±0.89 SD)] superior to the bifurcation of the carotid artery. CONCLUSIONS: During carotid endarterectomy procedure, using the cervical anatomic triangle region, as well as the angle of the mandible, the tip of the mastoid process, and the bifurcation of the carotid artery as anatomic landmarks, is of significant clinical importance for protecting the external branches of the superior laryngeal nerve.

Variations in the course of the externalbranch of the superior laryngeal nerveand their importance in surgicalprocedures: an experimental cadaveric study.

<br><b>Introduction:</b> Injury of the external branch of the superior laryngeal nerve can cause a hoarse or weak voice due to the functional loss (dysergia) of the cricothyroid muscle. Defining the anatomical variations of the external branch of the superior laryngeal nerve and estimating their frequency are crucial for surgical interventions.</br> <br><b>Aim:</b> To reveal the topography of the external branch in the Anatolian population, to prevent injury of it during the surgical intervention in the anterior neck region.</br> <br><b>Material and methods:</b> 26 bilateral hemilarynges (4 females, 22 males) were dissected. The morphometric and morphological features of the external branch were examined. The obtained results were compared statistically, left and right.</br> <br><b>Results:</b> Landmarks such as the thyroid gland and laryngeal prominence were determined for the detection of the external branch. The variations of the course of the external branch and the points of piercing the cricothyroid muscle or inferior pharyngeal constrictor muscle were evaluated.</br> <br><b>Discussion:</b> Although safe approaches have been described for nerve protection during neck surgeries, injuries may occur during preliminary surgery as the mentioned nerve is thinner and more superficial than other branches of the vagus nerve. However, it can be detected more easily and safely by knowing the defined anatomical landmarks and morphological variations of the external branch.</br> <br><b>Conclusion:</b> The anatomical variations described can be a safe and important guide in surgeries of the anterior neck region.</br>.

Variations of the external branch of the superior laryngeal nerve during its course and its importance in surgical approaches: an experimental cadaveric study.

INTRODUCTION: Injury of the external branch of the superior laryngeal nerve can cause a hoarse or weak voice due to the functional loss (dysergia) of the cricothyroid muscle. Defining the anatomical variations of the external branch of the superior laryngeal nerve and estimating the frequency of it, it makes crucial for surgical interventions. AIM: To reveal the topography of the external branch in the Anatolian population, to prevent injury of it during the surgical intervention in the anterior neck region. MATERIALS AND METHODS: Twenty-six bilateral hemilarynges (4 females, 22 males) were dissected. The morphometric and morphological features of the external branch were examined. The obtained results were compared statistically left and right. RESULTS: Landmarks such as the thyroid gland and laryngeal prominence were determined for the detection of the external branch. The variations of the course of the external branch and the points of piercing the cricothyroid muscle or inferior constrictor pharyngeal muscle were evaluated. DISCUSSION: Although safe approaches have been described for nerve protection during neck surgeries, it can expose injuries during preliminary surgery approaches as the nerve is thinner and more superficial than other branches of the vagus nerve. However, it can be detected more easily and safely during the surgical approach by knowing the defined anatomical landmarks and morphological variations of the external branch. CONCLUSION: The anatomical variations described can be a safe and important guide in surgical approaches to be applied in the anterior neck region.

Early Internal Branch of Superior Laryngeal Nerve Bifurcation Passes Through Double Thyroid Foramen.

Internal branch of superior laryngeal nerve (ibSLN) provides sensory innervation mostly to the supraglottic part of the larynx and thus prevents aspiration during ingestion. Normally, it is distributed to the larynx after piercing the thyrohyoid membrane above the superior laryngeal artery. Multiple anatomical variations in the course of ibSLN have been reported. An early ibSLN bifurcation and course through double thyroid foramen constitutes an interesting anatomical variation that may easily lead to an injury during procedures in the thyroid gland and the larynx. Knowledge of the anatomical variability is essential in order to prevent surgical complications that could potentially impact the patient's quality of life.

Superior Laryngeal Nerve Palsy After Anterior Cervical Diskectomy and Fusion: A Case Report and Cadaveric Description.

BACKGROUND AND IMPORTANCE: Superior laryngeal nerve (SLN) injury after high cervical dissection can result in changes in vocal pitch due to cricothyroid denervation and dysphagia with aspiration risk because of decreased sensation of the supraglottic larynx. CLINICAL PRESENTATION: We describe a 69-year-old singer with cervical spondylotic myelopathy who underwent elective C3/4 and C4/5 anterior cervical diskectomy and fusion. Postoperatively, the patient reported changes in his voice, most noticeable with higher registers. A number of studies confirmed severe right superior laryngeal neuropathy. A cadaveric description included to highlight anatomic relationships critical in minimizing risk of SLN injury during an anterior cervical diskectomy and fusion approach. CONCLUSION: The SLN is a critical structure vulnerable to iatrogenic injury during high cervical dissections for anterior approaches to the spine. Therefore, it is critical for spine surgeons to have a firm understanding of SLN anatomy for these approaches.

A novel method to reconstruct right recurrent laryngeal nerve by transforming into nonrecurrent laryngeal nerve: The end-to-free vagal laryngeal branch end anastomosis.

The objective of this study is to demonstrate a novel method for the reconstruction of right recurrent laryngeal nerve (RLN) by transforming into nonrecurrent RLN: the end-to-free vagal laryngeal branch end anastomosis. Here we report a case of locally advanced thyroid carcinoma. The patient underwent radical thyroid surgery with inevitably partial RLN resection and immediate right RLN reconstruction at our institution. With the guidance of intraoperative neuromonitoring (IOMN), we completed a novel end-to-free vagal laryngeal branch end anastomosis. The whole procedure was deliberately monitored by IOMN. Surgeons can procure adequate free nerve for tension-free anastomosis by transforming the right RLN into nonrecurrent nerve. Follow-up laryngoscope showed improved adductory movement of the right arytenoid. The end-to-free vagal end anastomosis is an effective way to reconstruct segmental nerve resection of right RLN. Its long-term postoperative result needs to be further warranted.

Anatomical and functional identification of the external branch of the superior laryngeal nerve: classification based on morphology and electrophysiological monitoring.

BACKGROUND: Motor function of the external branch of superior laryngeal nerve (EBSLN) is vital for voice quality. We studied the rate of EBSLN identification and integrity in the era of intraoperative neuromonitoring (IONM). METHODS: Anatomic and functional identification of 515 EBSLNs-at-risk was performed under the guidance of IONM that motor integrity was electrophysiologically checked. The functional integrity was assessed with crico-thyroid muscle (CTM) twitches and/or recordable waveform amplitude. We tried to establish the systematic classification of EBSLN identification and integrity. RESULTS: Visual, electrophysiological and total identification rates were 64.3%, 31.6% and 95.9%, respectively. We could identify 4.1% of EBSLNs neither anatomically nor electrophysiologically. We recorded CTM twitches alone or both CTM twitches and wave amplitude in 203(39.4%) and 291(56.5%) branches respectively. Identification features of EBSLNs were systematically classified under three main types: Visualized-monitored (1), non-visualized-monitored (2), unidentified (3), and electrophysiological integrity of EBSLNs under two subtypes: CTM twitches alone (a) and CTM twitches and wave amplitude (b). CONCLUSION: Dedicated thyroid surgeon could visually identify EBSLNs. IONM contribution significantly increases the identification rate. Systematic classification of identification and electrophysiological integrity of EBSLNs may increase comprehensive knowledge about its motor function that is crucial for complication-free thyroidectomy.

Correlation Between Objective and Subjective High-Pitched Voice Impairment in Patients After Thyroid Surgery.

Objectives: High-pitched voice impairment (HPVI) is not uncommon in patients without recurrent laryngeal nerve (RLN) or external branch of superior laryngeal nerve (EBSLN) injury after thyroidectomy. This study evaluated the correlation between subjective and objective HPVI in patients after thyroid surgery. Methods: This study analyzed 775 patients without preoperative subjective HPVI and underwent neuromonitored thyroidectomy with normal RLN/EBSLN function. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were performed during the preoperative(I) period and the immediate(II), short-term(III) and long-term(IV) postoperative periods. The severity of objective HPVI was categorized into four groups according to the decrease in maximum frequency (Fmax): <20%, 20-40%, 40-60%, and >60%. Subjective HPVI was evaluated according to the patient's answers on the IVST. Results: As the severity of objective HPVI increased, patients were significantly more to receive bilateral surgery (p=0.002) and have subjective HPVI (p<0.001), and there was no correlation with IVST scores. Among 211(27.2%) patients with subjective HPVI, patients were significantly more to receive bilateral surgery (p=0.003) and central neck dissection(p<0.001). These patients had very similar trends for Fmax, pitch range, and mean fundamental frequency as patients with 20-40% Fmax decrease (p>0.05) and had higher Jitter, Shimmer, and IVST scores than patients in any of the objective HPVI groups; subjective HPVI lasted until period-IV. Conclusion: The factors that affect a patient's subjective HPVI are complex, and voice stability (Jitter and Shimmer) is no less important than the Fmax level. When patients have subjective HPVI without a significant Fmax decrease after thyroid surgery, abnormal voice stability should be considered and managed. Fmax and IVST scores should be interpreted comprehensively, and surgeons and speech-language pathologists should work together to identify patients with HPVI early and arrange speech therapy for them. Regarding the process of fibrosis formation, anti-adhesive material application and postoperative intervention for HPVI require more future research.

Superior Laryngeal Nerve Signal Attenuation Influences Voice Outcomes in Thyroid Surgery.

OBJECTIVES/HYPOTHESIS: The objective was to identify whether injury of the external branch of the superior laryngeal nerve (EBSLN) or changes in EBSLN parameters after dissection during thyroidectomies correlate with changes in voice quality postoperatively. STUDY DESIGN: Prospective multicenter case series. METHODS: A prospective multicenter study was conducted on patients undergoing thyroidectomies with intraoperative nerve monitoring. Electromyography waveforms of EBSLN stimulation before (S1) and after superior pole dissection (S2) were evaluated using endotracheal tube (ETT) and cricothyroid intramuscular (CTM) electrodes. Voice outcomes were assessed using Voice-Related Quality of Life Surveys and Voice Handicap Index. RESULTS: A total of 131 at-risk EBSLNs were evaluated in 80 patients. Two nerves showed loss of CTM twitch coupled with an absent S2 signal response. Complete EBSLN loss of signal was more likely with: 1) Cernea EBSLN anatomic classification Type 2B; 2) with a longer distance from the sternothyroid muscle insertion site; and 3) with larger lobar volumes (P < .05). Patients who experienced a more than 50% decrement in CTM amplitudes of S2 (n = 7) by CTM electrodes had a statistically significant decline in their voice outcomes compared to those who did not (n = 69) (P < .05). CONCLUSIONS: Patients experienced worse voice outcomes when at least one EBSLN response amplitude decreased by more than 50% after dissection when measured by CTM needle electrodes. CTM needle electrodes have an ability to measure finer amplitude changes compared to ETT electrodes, may represent a safe method to deduce subtle EBSLN injuries, and may serve to optimize voice outcomes during thyroidectomy. CTM needle electrodes are safe and tolerated well. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:1436-1442, 2021.

Anatomical Variations in Recurrent Laryngeal Nerves in Thyroid Surgery.

OBJECTIVE: To study terminal bifurcation of recurrent laryngeal nerves (RLNs) with original direction to larynx entry and to decrease the risk of vocal cord paralysis in thyroid patients. METHODS: The RLNs of 294 patients (482 sides) were dissected according to the branches into the larynx, and the original direction of each RLN trunk in thyroid surgery was recorded. RESULTS: (1) About 30.9% of the RLNs gave off multiple branches into the larynx. (2) Two and 3 branches of RLNs into the larynx were found in 25.5% and 5.4% of the cases, respectively. (3) In 0.4% or 2 cases, the RLN trunk combined with the inferior branch of the vagus nerve. (4) Nonrecurrent laryngeal nerve appeared in 2 cases. (5) On the left side, 68.0%, 25.6%, and 6.4% of cases were found with 1, 2, and 3 bifurcations of RLN to larynx entry, respectively. On the right side, 69.8%, 25.8%, and 4.4% cases were identified with 1, 2, and 3 bifurcations of RLN to larynx entry, respectively. (6) The combining dissection approach was proved as successful and safe for protecting the RLN with no permanent RLN paresis. CONCLUSIONS: Because of the anatomical variation in RLNs with extralaryngeal bifurcation, it is necessary to increase the awareness of surgeons about these variations so as to protect bifurcated nerves in thyroid surgery.

Ultrasound-guided internal branch of superior laryngeal nerve block on postoperative sore throat: A randomized controlled trial.

INTRODUCTION: Ultrasound-guided internal branch of the upper laryngeal nerve block (USG-guided iSLN block) have been used to decrease the perioperative stress response of intubation. It is more likely to be successful than blindly administered superior laryngeal nerve blocks with fewer complications. Here, we evaluated the efficacy of USG-guided iSLN block to treat postoperative sore throat (postoperative sore throat, POST) after extubation. METHODS: 100 patients, aged from 18 to 60 years old, ASA I~II who underwent general anesthesia and suffered from the moderate to severe postoperative sore throat after extubation were randomized into two groups(50 cases per group). Patients in group S received USG-guided iSLN block bilaterally (60mg of 2% lidocaine, 1.5ml each side), whereas those in group I received inhalation with 100 mg of 2% lidocaine and 1mg of budesonide suspension diluted with normal saline (oxygen flow 8 L /min, inhalation for 15 minutes). The primary outcome were VAS scores in both groups before treatment (T0), 10 min (T1), 30 min(T2), 1h(T3), 2 h(T4), 4h(T5), 8h(T6), 24h(T7), and 48h(T8) after treatment. The secondary outcome were satisfaction scores after treatment, MAP, HR, and SPO2 fromT0 to T8. The adverse reactions such as postoperative chocking or aspiration, cough, hoarseness, dyspnea were also observed in both groups. RESULTS: Patients in group S had significantly lower VAS score than that in group I at points of T1 ~ T6 (P < 0.01). HR of group S was lower than that of group I at points of T1 ~ T2and T4 (P < 0.05), and MAP was lower than that of group I at points of T1 ~ T3 (P < 0.05). Satisfaction scores of group S were higher than that of group I (P <0.05), In group S, 2 case (4%) needed to intravenous Flurbiprofen Injection 50 mg to relieve pain; in group I, 13 cases (26%) received Flurbiprofen Injection. 2 case of group S appeared throat numbness after treatment for 3 hours; 2 patients have difficult in expectoration after treatment recovered after 3hour. No serious adverse events were observed in both groups. CONCLUSION: Compared with inhalation, USG-guided iSLN block may effectively relieve the postoperative sore throat after extubation under general anesthesia and provided an ideal treatment for POST in clinical work.

The strap intermuscular approach can significantly increase the exposure rate of the external branch of the superior laryngeal nerve during thyroid surgery.

BACKGROUND: Avoiding injury to the external branch of the superior laryngeal nerve (EBSLN) is a major challenge during thyroid surgery. EBSLN injury can have an impact on the quality of life of patients. The aim of this study was to introduce the strap intermuscular approach, to dissect the EBSLN with two different approaches in thyroid surgery, to compare the differences between these two approaches, and to describe a way for surgeons to treat the upper thyroid gland to find the EBSLN. METHODS: A prospective study of hemithyroidectomy was performed. In total, 104 patients were included and randomly divided into two groups: one group used the traditional approach to expose and protect the EBSLN, and the other group used the strap intermuscular approach. We described the surgical procedure for the strap intermuscular approach and compared the differences in the rates of EBSLN exposure, injury, and classification to illustrate the advantages of the intermuscular approach in thyroid surgery. RESULTS: The exposure rate of the EBSLN was higher with the strap intermuscular approach than with the traditional approach (96.15% vs. 76.92%, p = 0.01), with an odds ratio (OR) and 95% confidence interval (CI) of 0.133 (0.028-0.630). The exposure rate of EBSLNs classified as type 1 was higher in the strap intermuscular approach than in the traditional approach (30.77% vs. 13.46%, p = 0.033), with an OR and 95% CI of 0.350 (0.130-0.942). CONCLUSIONS: The exposure rate of the EBSLN was significantly higher with the strap intermuscular approach method than with the traditional approach during thyroid surgery. This approach allows for better identification of the EBSLN during thyroidectomy.

Swallowing dysfunction following surgery for well-differentiated thyroid cancer with extrathyroid invasion.

BACKGROUND: Differentiated thyroid carcinoma (DTC) can invade the surrounding aerodigestive tract. Radical surgery for locally advanced DTC will require resection of the trachea, recurrent laryngeal nerve (RLN), inferior pharyngeal constrictor muscles (IPCMs), or a part of the esophagus. The purpose of this study was to demonstrate the effect of resection of these surrounding tissues combined with total thyroidectomy and neck dissection on swallowing function following surgery. METHODS: We performed total thyroidectomy combined with neck dissection and resection of the RLN in 24 patients with DTC with extrathyroidal invasion (19 unilateral, 1 bilateral), IPCMs (n = 5), or muscle layers of esophagus (n = 9). Nine patients received a tracheostomy placement due to a window resection of the trachea for tumor invasion (n = 6) and necessary upper airway management (n = 3). We used the duration of nasogastric tube feeding to evaluate swallowing function following surgery. RESULTS: Patients who underwent tracheostomy or IPCM resection showed significantly longer periods of tube feeding (p = 0.0057 and 0.0017, respectively). In contrast, resection of the unilateral RLN or esophageal muscle layer showed no difference in tube feeding duration. Multiple regression analysis indicated that tracheostomy and IPCM resection were significant independent predictors of longer periods of tube feeding (p = 0.04583 and 0.00087, respectively). CONCLUSION: These results indicate that tracheostomy placement and resection of the IPCMs, together with total thyroidectomy, extends the tube feeding duration in the postoperative period.

Superior laryngeal nerve transection for neuropathic cough: A pilot study.

OBJECTIVE: To describe a novel surgical therapy for the treatment of medically refractory neuropathic cough, in which carefully selected subjects undergo surgical transection of the internal branch of the superior laryngeal nerve (iSLN). METHODS: Subjects with a diagnosis of neuropathic cough, who were not improved after two medication trials, underwent iSLN block with local anesthetic in the office. While anesthetized, they underwent provocative testing to determine whether the nerve block improved their symptoms; if so, a modified barium swallow study (MBSS) was performed to determine whether they still swallowed safely without supraglottic sensation. Those who passed this screening were offered operative iSLN transection. We retrospectively reviewed our results to date. RESULTS: Six subjects (5 females, ages 46-71), with neuropathic cough symptoms for 2-15 years, passed the screening and underwent iSLN transection procedures. At a mean follow-up of 8.2 months, significant symptomatic relief was experienced by 5/6 subjects, with Cough Severity Index (CSI) scores averaging 34.83 ± 6.94 pre-op (range 36-40) and 15.5 ± 11.81 post-op (range 0-29) (p = 0.043). Operative time averaged 49 min (range 30-64). There were no major complications. No subjects experienced post-op aspiration problems. CONCLUSION: This preliminary data supports iSLN transection as a viable option for subjects with refractory neuropathic cough. Our screening algorithm identifies subjects that would be expected to improve with this procedure and confirms a safe swallow.

Bilateral Selective Laryngeal Reinnervation for Bilateral Vocal Fold Paralysis in Children.

Importance: Bilateral vocal fold paralysis (BVFP) in pediatric patients is a challenging entity with multiple causes. Traditional approaches to managing BVFP include tracheostomy, arytenoidectomy, suture lateralization, cordotomy, and posterior cricoid enlargement. These interventions are used to create a stable airway but risk compromising voice quality. Objectives: To assess the use of bilateral selective laryngeal reinnervation (SLR) surgery to manage BVFP and restore dynamic function to the larynx in pediatric patients. Design, Setting, and Participants: In this case series performed at 2 tertiary care academic institutions, 8 pediatric patients underwent bilateral SLR to treat BVFP (5 patients with iatrogenic BVFP and 3 with congenital BVFP) from November 2004 to August 2018 with follow-up for at least 1.5 years. Interventions: Bilateral selective laryngeal reinnervation surgery. Main Outcomes and Measures: Flexible laryngoscopy findings, subjective and objective measures of voice quality, subjective swallowing function, and decannulation in patients who were previously dependent on a tracheostomy tube. Results: Participants included 6 boys and 2 girls with a median age of 9.3 (range, 2.2 to 18.0) years at the time of surgery. All 8 patients were decannulated; 6 patients had preoperative tracheostomies and 2 had perioperative tracheostomies. Voice quality, as measured using the GRBAS (grade, roughness, breathiness, asthenia, strain) scale, improved in 6 of 8 patients after reinnervation, and swallowing was not impaired in any patients. In 2 patients, GRBAS scale scores remained the same before and after surgery. Inspiratory vocal fold abduction was observed on both sides in 5 patients and on 1 side in 2 patients, with no active abduction observed in 1 patient. The follow-up period was more than 5 years in 7 of 8 patients and at least 1.5 years in all patients. Conclusions and Relevance: Bilateral SLR appears to be a promising treatment option for children with BVFP; it is currently the only option, to our knowledge, with the potential to restore abductor and adductor vocal fold movement. In patients with complete paralysis, this procedure may provide a strategy for airway management and restoration of the dynamic function of the larynx. It could be considered as a first-line technique before endolaryngeal or airway framework procedures, which carry a risk of compromising voice quality.

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.

Laryngeal adductor function following potassium titanyl phosphate laser welding of the recurrent laryngeal nerve.

OBJECTIVES/HYPOTHESIS: Recurrent laryngeal nerve (RLN) transection injuries may occur during thyroidectomy and other surgical procedures. Laser nerve welding has been shown to cause less technique-related axonal damage than the traditional suture method. We compared functional adductor results using these two methods of RLN repair. STUDY DESIGN: Animal model. METHODS: Canine hemilarynges underwent pretreatment testing of laryngeal adductor function, followed by RLN transection and repair using potassium titanyl phosphate (KTP) laser welding (n = 8) or microneural suture (n = 16) techniques. Six months later, adductor function was measured again and expressed as a proportion of the pretreatment value. RESULTS: The mean laryngeal adductor pressure ratios were 82.4% (95% confidence interval [CI]: 72.8%-92.0%) for the laser repair group and 55.5% (95% CI: 49.4%-61.6%) for the suture control group, with a difference of 26.9% (95% CI: 15.3%-38.5%). Both spontaneous and stimulated glottic closure was observed in the laser welding and microsuture repair groups. CONCLUSIONS: Laser nerve welding resulted in greater strength of adduction than suture repair of an acutely transected RLN. Suture anastomosis may traumatize more axons than the laser. Stronger vocal fold adduction is associated clinically with better protection from aspiration and improved voice outcomes. KTP laser welding should be considered for anastomosis of the RLN and other nerves. LEVEL OF EVIDENCE: NA Laryngoscope, 130:1764-1769, 2020.

Predictors of voice outcome in pediatric non-selective laryngeal reinnervation.

OBJECTIVES: Non-selective laryngeal reinnervation (NSLR) using the ansa cervicalis to the recurrent laryngeal nerve (RLN) is a promising treatment option for pediatric unilateral neuronal vocal fold movement impairment (VFMI). The aim is to describe our clinical outcomes with this technique and to identify preoperative characteristics that may predict postoperative voice outcomes. METHODS: This is a cohort study of pediatric patients with unilateral neuronal VFMI, who underwent NSLR from March 2012 to July 2018. Pre- and postoperative Pediatric Voice Related Quality of Life (PVRQOL) questionnaires, Consensus Auditory Perceptual Evaluation of Voice (CAPE-V) ratings, and objective voice measures were obtained. In addition, patients underwent preoperative laryngeal electromyography (LEMG). RESULTS: Thirty-two patients were identified. Twenty-one had complete data sets for analysis. The mean duration of VFMI was 9.02 years (range 1.1-26.1 years). There were significant improvements in PVRQOL (P = .0005), in all CAPE-V subsets (P ≤ .0001 to .0195), mean and maximum intensities (P = .0342 and 0.0110, respectively), cepstral peak prominence (P = .0001), and cepstral spectral index of dysphonia (P ≤ .0001). A worse preoperative LEMG correlated with a greater change in maximum phonation time (P = .0162) and maximum intensity (P = .0346). Age at injury and duration of injury had no significant impact on voice outcomes; however, patients with concurrent posterior glottic insufficiency did have smaller changes in PVRQOL (P = .012). CONCLUSION: NSLR is an effective treatment for pediatric unilateral neuronal VFMI even many years after initial RLN injury. LEMG may help predict voice outcomes of reinnervation in pediatric patients, but further data is still needed. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:1525-1531, 2020.