Assessment of Voice Quality and Vocal Cord Paralysis After Endarterectomy.

Introduction: Recurrent laryngeal nerve palsy is a rare but important complication after endarterectomy (CEA). The impact on voice quality after this procedure is also important. The aim of the study was to assess voice quality and vocal cord function after CEA. Material and Methods: 200 patients were enrolled in the study. Inclusion criteria were indications for CEA and patient consent to the procedure. Endoscopic examination of the larynx was performed before the procedure, immediately after the procedure, on the 2nd day after the procedure, then 3 month and 6 months after the procedure. Voice was assessed by maximum phonation time (MPT), GRBAS scale, Voice Handicap Index (VHI) and the Voice-Related Quality of Life (V-RQOL) questionnaire. Results: In the study group, the results on the GRBAS scale were significantly worse and the average MPT was shorter compared to the control group. In the V-RQOL assessment, patients rated their voice as fair or good, significantly more often noticed that they had difficulty speaking loudly and being heard, and that they felt short of air when speaking. In VHI-30, the total score was significantly higher in the study group compared to the control group. Voice disorders after the procedure were reported by 68 patients, while a disorder of the recurrent laryngeal nerve was observed immediately after the procedure in 32 patients. Most vocal cord disorders were transient. Ultimately, 3% of patients were diagnosed with vocal cord paralysis. Conclusion: Cranial nerves paralysis, including the recurrent laryngeal nerve, are a common complication after CEA. Majority the paralysis is transient, but requires appropriate diagnostic and therapeutic procedures. Vocal cord evaluation is a non-invasive and widely available examination and should be performed pre- and postoperatively after all neck surgeries. The incidence of voice disorders after CEA significantly affects the quality of life of patients and requires voice rehabilitation and patient care with psychological support.

Prognostic Indicators of Non-Transection Nerve Injury and Vocal Fold Motion Impairment After Thyroid Surgery - Correlation Between Intraoperative Neuromonitoring Findings and Perioperative Voice Parameters.

Objectives: In patients with recurrent laryngeal nerve (RLN) injury after thyroid surgery, unrecovered vocal fold motion (VFM) and subjective voice impairment cause extreme distress. For surgeons, treating these poor outcomes is extremely challenging. To enable early treatment of VFM impairment, this study evaluated prognostic indicators of non-transection RLN injury and VFM impairment after thyroid surgery and evaluated correlations between intraoperative neuromonitoring (IONM) findings and perioperative voice parameters. Methods: 82 adult patients had postoperative VFM impairment after thyroidectomy were enrolled. Demographic characteristics, RLN electromyography (EMG), and RLN injury mechanism were compared. Multi-dimensional voice program, voice range profile and Index of voice and swallowing handicap of thyroidectomy (IVST) were administered during I-preoperative; II-immediate, III-short-term and IV-long-term postoperative periods. The patients were divided into R/U Group according to the VFM was recovered/unrecovered 3 months after surgery. The patients in U Group were divided into U1/U2 Group according to total IVST score change was <4 and ≥4 during period-IV. Results: Compared to R Group (42 patients), U Group (38 patients) had significantly more patients with EMG >90% decrease in the injured RLN (p<0.001) and thermal injury as the RLN injury mechanism (p=0.002). Voice parameter impairments were more severe in U Group compared to R Group. Compared to U1 group (19 patients), U2 Group (19 patients) had a significantly larger proportion of patients with EMG decrease >90% in the injured RLN (p=0.022) and thermal injury as the RLN injury mechanism (p=0.017). A large pitch range decrease in period-II was a prognostic indicator of a moderate/severe long-term postoperative subjective voice impairment. Conclusion: This study is the first to evaluate correlations between IONM findings and voice outcomes in patients with VFM impairment after thyroid surgery. Thyroid surgeons should make every effort to avoid severe type RLN injury (e.g., thermal injury or injury causing EMG decrease >90%), which raises the risk of unrecovered VFM and moderate/severe long-term postoperative subjective voice impairment. Using objective voice parameters (e.g., pitch range) as prognostic indicators not only enables surgeons to earlier identify patients with low voice satisfaction after surgery, and also enable implementation of interventions sufficiently early to maintain quality of life.

New Developments in Anterior Laryngeal Recording Technique During Neuromonitored Thyroid and Parathyroid Surgery.

A recurrent laryngeal nerve (RLN) injury resulting in vocal fold paralysis and dysphonia remains a major source of morbidity after thyroid and parathyroid surgeries. Intraoperative neural monitoring (IONM) is increasingly accepted as an adjunct to the standard practice of visual RLN identification. Endotracheal tube (ET) surface recording electrode systems are now widely used for IONM; however, the major limitation of the clinical use of ET-based surface electrodes is the need to maintain constant contact between the electrodes and vocal folds during surgery to obtain a high-quality recording. An ET that is malpositioned during intubation or displaced during surgical manipulation can cause a false decrease or loss of electromyography (EMG) signal. Since it may be difficult to distinguish from an EMG change caused by a true RLN injury, a false loss or decrease in EMG signal may contribute to inappropriate surgical decision making. Therefore, researchers have investigated alternative electrode systems that circumvent common causes of poor accuracy in ET-based neuromonitoring. Recent experimental and clinical studies have confirmed the hypothesis that needle or adhesive surface recording electrodes attached to the thyroid cartilage (transcartilage and percutaneous recording) or attached to the overlying neck skin (transcutaneous recording) can provide functionality similar to that of ET-based electrodes, and these recording methods enable access to the EMG response of the vocalis muscle that originates from the inner surface of the thyroid cartilage. Studies also indicate that, during surgical manipulation of the trachea, transcartilage, percutaneous, and transcutaneous anterior laryngeal (AL) recording electrodes could be more stable than ET-based surface electrodes and could be equally accurate in depicting RLN stress during IONM. These findings show that these AL electrodes have potential applications in future designs of recording electrodes and support the use of IONM as a high-quality quantitative tool in thyroid and parathyroid surgery. This article reviews the major recent developments of newly emerging transcartilage, percutaneous, and transcutaneous AL recording techniques used in IONM and evaluates their contribution to improved voice outcomes in modern thyroid surgery.

Functional recurrent laryngeal nerve regeneration using a silicon tube containing a collagen gel in a rat model.

In this study, we examined the effect of differing gap lengths on regeneration of transected recurrent laryngeal nerves using silicon tubes containing type I collagen gel and the ability of this regeneration to result in restoration of vocal fold movements in rats. We simulated nerve gaps in Sprague-Dawley rats by transecting the left recurrent laryngeal nerves and bridged the nerve stumps using silicon tubes containing type 1 collagen gel. Three experimental groups, in which the gap lengths between the stumps were 1, 3, or 5 mm, were compared with a control group in which the nerve was transected but was not bridged. After surgery, we observed vocal fold movements over time with a laryngoscope. At week 15, we assessed the extent of nerve regeneration in the tube, histologically and electrophysiologically. We also assessed the degree of atrophy of the thyroarytenoid muscle (T/U ratio). Restoration of vocal fold movements was observed in 9 rats in the 1-mm group, in 6 rats in the 3-mm group, and in 3 rats in the 5-mm group. However, in most rats, restoration was temporary, with only one rat demonstrating continued vocal fold movements at week 15. In electromyograph, evoked potentials were observed in rats in the 1-mm and 3-mm groups. Regenerated tissue in the tube was thickest in the 1-mm group, followed by the 3-mm and 5-mm groups. The regenerated tissue showed the presence of myelinated and unmyelinated nerve fibers. In assessment of thyroarytenoid muscle atrophy, the T/U ratio was highest in the 1-mm group, followed by the 3-mm and 5-mm groups. We successfully regenerated the nerves and produced a rat model of recurrent laryngeal nerve regeneration that demonstrated temporary recovery of vocal fold movements. This rat model could be useful for assessing novel treatments developing in the future.

Recurrent laryngeal nerve monitoring during thyroidectomy and parathyroidectomy in children.

OBJECTIVE: Injury of the recurrent laryngeal nerve (RLN) is the most frequent complication of thyroid and parathyroid (TP) surgery. Monitoring of the RLN in children is not widely studied as this is not a common disease in the pediatric population. The aim of our study was to evaluate the reliability, feasibility and benefits of RLN monitoring during TP surgery in children. METHODS: We analyzed all children who underwent TP surgery in our department between January 2009 and March 2018. Patients were classified into three groups: without monitoring (group 1), monitoring with an endotracheal tube (group 2) and monitoring with a double-needle electrode placed through the cricothyroid ligament (group 3). RESULTS: We performed 53 surgeries (77 RLNs at risk) on 47 patients aged between 6 months and 18 years. Fourteen RLNs were in group 1, 47 in group 2 and 16 in group 3. We found one transient lesion of the RLN in group 1, three in group 2 and two in group 3. Seven patients in group 3 could not undergo monitoring with the tube because they need an orotracheal tube smaller than the smallest monitoring tube size available. The sensitivity and specificity values of the monitoring methods were 33% and 97% in group 2 and 67% and 100% in group 3, respectively. The positive and negative predictive values were 50% and 95% in group 2 and 100% and 92% in group 3, respectively. No complications arose during insertion of the electrode through the cricothyroid ligament. CONCLUSION: Monitoring of the RLN with a double-needle electrode inserted through the cricothyroid ligament is a reliable method with no associated complication, which is achievable at any age.

Precision treatment of post pneumonectomy unilateral laryngeal paralysis due to cancer.

Aim: The aim of this study is to assess the efficacy of external laryngeal medialization acquired through a Gore-Tex implant in a 45 patients affected by unilateral vocal fold paralysis in abduction after pneumonectomy. Method: The cohort of patients was made up of 30 male (73.1%) and 11 female patients (26.9%) with an average age of 66.7 years in a range between 46 and 78 years. Results: The results were analyzed with the objective and subjective analysis of voicing and swallowing. In 95.2% of cases, voice and swallow improvement with statistically significant evidences. Conclusion: We can conclude that Gore-Tex implantation is a simple, reproducible and minimally invasive procedure for management of selected cases of vocal fold unilateral paralysis in the abductory position.

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

Background: The correlation between the injured recurrent laryngeal nerve (RLN) with incomplete loss of signal (LOS) and the outcomes of vocal cord function is still not well understood. This large cohort validation study was aimed to evaluate the effectiveness of the warning criterion, the reduction of the R2p/R2d ratio, in neuromonitoring during thyroidectomy. Methods: A total of 1108 consecutive patients (1764 nerves) with normal vocal cord function undergoing monitored thyroidectomy were included. Standardized intraoperative neuromonitoring procedures were strictly followed, after complete dissection of RLN, the exposed RLN was routinely stimulated at the lowest proximal end (R2p signal) and the most distal end near the laryngeal entry point (R2d signal). If the reduction of the R2p/R2d ratio (([R2d - R2p]/R2d) × 100%) reached >20%, the whole exposed RLN would be checked to pinpoint the injured area of the nerve. Results: Visual anatomical integrity of the RLN was ensured in all 1764 nerves. Eighteen nerves had complete LOS, and the other 97 nerves had incomplete LOS where the reduction of the R2p/R2d ratio ranged from 21% to 84%. Postoperative temporary vocal cord paralysis (VCP) was noted in 11 (61.1%) RLNs with complete LOS and 16 (16.5%) RLNs with incomplete LOS, where the reduction of the R2p/R2d ratio ranged from 63% to 84%. The positive predictive value of a R2p/R2d ratio >63% for postoperative VCP was 79.4%. Conclusions: Testing and comparing the R2p and R2d signals were useful to detect RLN neurophysiologic injury, elucidating the mechanism of nerve injury and predicting vocal cord function. Determining R2p-R2d was found to be essential and can be applied in routine neuromonitoring thyroidectomy.

Early Injection Laryngoplasty After Surgery: 30 Cases and Proposed Aspiration Assessment Protocol.

Vocal fold movement impairment may significantly compromise postoperative recovery and quality of life of patients following thoracic or cardiothoracic surgery or prolonged intubation. The literature is limited and there is no standard screening protocol for the optimal postoperative swallowing and aspiration evaluations. We performed retrospective review of adult patients undergoing early vocal fold (VF) injection laryngoplasty for acute postoperative Vocal fold movement impairment (<30 days) that had both pre- and postinjection speech language pathologist (SLP) performed swallowing/aspiration evaluations. Records were reviewed for demographics, clinical characteristics, procedural details, and short-term outcome measures of oral intake. In total, 30 patients were included, and had data on swallowing/aspiration studies before and after the VF injection laryngoplasty. Most of the patients were injected within 5 days following the laryngologist evaluation and within 14 days following the iatrogenic recurrent laryngeal nerve injury (23/30, 76.7%). The majority of patients were injected at the bedside by awake transcutaneous injection (22/30, 73.3%), six patients were injected in the operating room under general anesthesia, and two at the outpatient clinic. Pre- and postinjection SLP evaluations included clinical bedside assessment or instrumental evaluation. Following VF injection laryngoplasty, oral diet advancement was noted in 81.8% of the patients that were nil per os before the injection (18/22). No complications were noted. In conclusions, acute VFMI following surgery requires immediate diagnosis and therapeutic strategy to minimize postoperative complications and to overcome impairments in the voice, swallow, and cough. Otolaryngology-SLP interdisciplinary aspiration and swallowing assessment protocol is proposed based on our experience and an extensive literature review.

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.

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.

Selective stimulation of human intrinsic laryngeal muscles: Analysis in a mathematical three-dimensional space.

OBJECTIVES/HYPOTHESIS: Standard stimulating methods using square waves do not appropriately restore physiological control of individual intrinsic laryngeal muscles (ILMs). To further explore our earlier study of evoked orderly recruitment by quasitrapezoidal (QT) currents, we integrated the contribution of the cricothyroideus (CT) with attention to mutual activation in an additional patient, based on recent studies of appropriate responses via strict recurrent laryngeal nerve (RLN) stimulation. STUDY DESIGN: Basic science study. METHODS: The patient received functional electrical stimulation (FES) with QT pulses at 5 Hz, 60 to 2,000 µAmp, 100 to 500 µs pulse width, 0 to 500 µs decay. Ipsilateral electromyography (EMG) responses were calculated using the average maximum amplitude, area under the curve, and the root mean square of the rectified amplitude waveforms. The thyroarytenoideus (TA), posterior cricoarytenoideus (PCA), lateral cricothyroideus (LCA), and the CT were each interrogated via two monopolar electrodes, values were recorded in MATLAB, exported to Excel, and analyzed. Individual and mutual recruitment configurations and activation delays with stimulation were explored using multiple regression and exploration factor analyses. RESULTS: A total of 868 EMG data points based on 18 trials and up to 11 subtrials were captured from each of the four ILMs. Various combinations of pulse amplitude, pulse width, and exponential decay were found to produce significant (P ≤ .001) individual ILM responses. CT mirrored the LCA, whereas the TA and PCA exhibited separate interactions along shared trajectories in a three-dimensional space. CONCLUSIONS: FES calibrated to individual and coupled ILMs offers promise for restoring normal and pathological contraction patterns via strict RLN stimulation. LEVEL OF EVIDENCE: 5 Laryngoscope, 130:967-973, 2020.

Recurrent Laryngeal Nerve Morbidity: Lessons from Endoscopic via Bilateral Areola and Open Thyroidectomy Technique.

BACKGROUND AND AIM: Elucidating the mechanism of recurrent laryngeal nerve (RLN) injuries through intraoperative electromyographic (EMG) and laryngeal examination approaches may deepen our knowledge regarding its prevention strategies. To date, no studies have been reported on the mechanism of RLN injury caused by endoscopic thyroidectomy via bilateral areola approach (ETBAA). METHODS: Both intraoperative EMG profiles and postoperative laryngeal examination were used to investigate the mechanisms of RLN injury and compare the safety aspects between ETBAA and open thyroidectomy approach (OTA). RESULTS: This study examined 1420 nerves at risk. The mean follow-up period was 17 ± 4 (range 6-48) months. The incidence of vocal cord paralysis was 4.1% (59/1420). The number of cases with decreased EMG signals and vocal cord palsy was higher in ETBAA group than in OTA group (P < 0.05). The left RLNs in ETBAA group were at higher risk compared to the right nerves. CONCLUSIONS: The results of the current study indicate that ETBAA exhibits higher risk of RLN injury. The topic includes a video.

Learning Curve for Using Intraoperative Neural Monitoring Technology of Thyroid Cancer.

We investigated the learning curve for using intraoperative neural monitoring technology in thyroid cancer, with a view to reducing recurrent laryngeal nerve injury complications. Radical or combined radical surgery for thyroid cancer was performed in 82 patients with thyroid cancer and 147 recurrent laryngeal nerves were dissected. Intraoperative neural monitoring technology was applied and the "four-step method" used to monitor recurrent laryngeal nerve function. When the intraoperative signal was attenuated by more than 50%, recurrent laryngeal nerve injury was diagnosed, and the point and causes of injury were determined. The time required to identify the recurrent laryngeal nerve was 0.5-2 min and the injury rate was 2.7%; injuries were diagnosed intraoperatively. Injury most commonly occurred at or close to the point of entry of the nerve into the larynx and was caused by stretching, tumor adhesion, heat, and clamping. The groups are divided in chronological order; a learning curve for using intraoperative neural monitoring technology in thyroid cancer surgery was generated based on the time to identify the recurrent laryngeal nerve and the number of cases with nerve injury. The time to identify the recurrent laryngeal nerve and the number of injury cases decreased markedly with increasing patient numbers. There is a clear learning curve in applying intraoperative neural monitoring technology to thyroid cancer surgery; appropriate use of such technology aids in the protection of the recurrent laryngeal nerve.

Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses.

The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (PSA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified "subclinical" subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically.

Selective reinnervation using phrenic nerve and hypoglossal nerve for bilateral vocal fold paralysis.

OBJECTIVE: To evaluate the extent of airway improvement and voice quality in patients with bilateral vocal fold paralysis (BVFP) who underwent selective laryngeal reinnervation surgery. METHODS: Seven patients with BVFP caused by thyroid surgeries were enrolled. They underwent selective laryngeal reinnervation surgery. Videostroboscopy data, voice perceptual data (grade [G]), acoustic data, laryngeal electromyography data, and pulmonary function test data were obtained preoperatively and postoperatively. RESULTS: Videostroboscopic videos showed that six patients could achieve moderate-to-maximal abduction in the bilateral vocal folds during inspiration, whereas all patients achieved adduction in the bilateral vocal folds during phonation at 4 to 7 months postoperatively. G score was decreased significantly versus preoperative values (P < 0.05), and vocal functional parameters were improved significantly at 12 months postoperatively (P < 0.05). The aerodynamic parameter of maximum phonation time was significantly longer than the preoperative value (P < 0.05). Most parameters in pulmonary function test recovered to normal reference levels as early as 3 months postoperatively, whereas maximal inspiratory pressure (PImax) values were still slightly lower than normal levels 12 months after surgery. All of these parameters improved significantly versus preoperative values. Electromyographic data at 12 months postoperatively showed full interference potentials in bilateral posterior cricoarytenoid muscles during inspiration and full interference potentials in bilateral thyroarytenoid muscles during phonation in all patients. Moderate electric potentials were seen in left interarytenoid muscle in one failed patient. CONCLUSION: This new selective laryngeal reinnervation procedure can achieve physiological movements of the bilateral vocal folds in selected patients with BVFP. LEVEL OF EVIDENCE: 4. Laryngoscope, 129:2669-2673, 2019.

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.

Isolated Recovery of Adductor Muscle Function Following Bilateral Recurrent Laryngeal Nerve Injuries.

OBJECTIVES/HYPOTHESIS: The aim of this study was to analyze the phoniatric and respiratory outcomes of a subset of bilateral vocal cord paralysis (BVCP) patients who were all treated with unilateral endoscopic arytenoid abduction lateropexy (EAAL). EAAL is a nondestructive, minimally invasive glottis widening operation, which does not damage either the surgically treated or the contralateral vocal cord. Therefore, it does not impair the regeneration potential of the recurrent laryngeal nerve. STUDY DESIGN: Case series. METHODS: Ten out of 21 BVCP patients who were treated with EAAL showed signs of isolated adduction recovery at 1 year and were chosen for this study. Functional results (objective and subjective voice analysis, spirometric measurement) and vocal cord movements were assessed preoperatively, 1 week and 1 year after EAAL. Laryngeal electromyography was performed on the 12th postoperative month. RESULTS: The volitional adductor movement seen on laryngoscopy was corroborated by laryngeal electromyography evaluation. Peak inspiratory flow increased significantly after EAAL. Quality-of-life scores also showed high patient satisfaction. Shimmer showed consistent improvement along with harmonic-to-noise ratio and average maximal phonation time in parallel with the improving vocal cord movement. Complex voice analysis and subjective self-evaluation tests also demonstrated significant improvement. CONCLUSIONS: EAAL, as a minimally invasive, nondestructive airway widening technique, does not interfere with the potential regeneration process that can still occur after BVCP, allowing for laryngeal functional recovery. It is a safe and effective treatment for BVCP that allows a simple solution with good phonatory, swallowing, and respiratory benefits by unilateral passive and reversible vocal cord lateralization. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:2334-2340, 2019.

Vocal Fold Motion Recovery in Patients With Iatrogenic Unilateral Immobility: Cervical Versus Thoracic Injury.

OBJECTIVES:: Prognostic information about the return of vocal fold mobility in patients with iatrogenic unilateral vocal fold immobility (UVFI) can help with informed decisions about temporary and permanent treatment options. Although many variables can influence the likelihood of recovery, clinical experience suggests that cervical versus thoracic injury is a determining factor. The purpose of this study was to compare recovery rates from UVFI between cervical and thoracic injuries. METHODS:: A retrospective review of the medical record was performed on all adult patients diagnosed with complete iatrogenic UVFI from 2005 to 2015 (n = 923). Patients with incomplete data and etiologies of idiopathic, malignancy, or stenosis were excluded, leaving a study cohort of 502 patients who were categorized as having UVFI after cervical (n = 329) or thoracic (n = 173) injury. Data regarding site of iatrogenic injury (cervical vs thoracic), mobility status, and time interval to recovery or surgical intervention were recorded and compared using χ2 analyses. RESULTS:: Overall, 15% of patients recovered vocal fold mobility at a median of 4.1 months. Patients with cervical injury (65 of 329 [20%]) were significantly more likely to recover mobility than patients with thoracic injury (11 of 173 [6.4%]) (odds ratio, 3.63). The cervical cohort contained more women (68% vs 31%) and was younger (mean age, 60.4 ± 13.8 vs 64.1 ± 16.1 years; Cohen's D = 0.25). CONCLUSIONS:: Patients with cervical injuries resulting in UVFI are 4 times more likely to recover mobility than patients with thoracic injuries. This information can be valuable in counseling patients with UVFI and may affect clinical decision making.