Long-term stimulation by implanted pacemaker enables non-atrophic treatment of bilateral vocal fold paresis in a human-like animal model.

A wide variety of treatments have been developed to improve respiratory function and quality of life in patients with bilateral vocal fold paresis (BVFP). One experimental method is the electrical activation of the posterior cricoarytenoid (PCA) muscle with a laryngeal pacemaker (LP) to open the vocal folds. We used an ovine (sheep) model of unilateral VFP to study the long-term effects of functional electrical stimulation on the PCA muscles. The left recurrent laryngeal nerve was cryo-damaged in all animals and an LP was implanted except for the controls. After a reinnervation phase of six months, animals were pooled into groups that received either no treatment, implantation of an LP only, or implantation of an LP and six months of stimulation with different duty cycles. Automated image analysis of fluorescently stained PCA cross-sections was performed to assess relevant muscle characteristics. We observed a fast-to-slow fibre type shift in response to nerve damage and stimulation, but no complete conversion to a slow-twitch-muscle. Fibre size, proportion of hybrid fibres, and intramuscular collagen content were not substantially altered by the stimulation. These results demonstrate that 30 Hz burst stimulation with duty cycles of 40% and 70% did not induce PCA atrophy or fibrosis. Thus, long-term stimulation with an LP is a promising approach for treating BVFP in humans without compromising muscle conditions.

[Analysis of vocal fold movement characteristics in patients with laryngeal neurogenic injury].

Objective:To analyze the characteristics of vocal fold movement and glottic closure in patients with laryngeal neurogenic injury. Methods:A total of 185 patients with vocal fold paralysis diagnosed by laryngeal electromyography as neurogenic damage to cricothyroid muscle, thyreoarytenoid muscle and posterior cricoarytenoid muscle were enrolled, they were divided into unilateral vocal fold paralysis group and bilateral vocal fold paralysis group, respectively, and superior laryngeal paralysis group, recurrent laryngeal nerve paralysis group and vagal nerve paralysis group according to nerve injury. The characteristics of vocal fold movement and glottic closure were analyzed under strobe laryngoscope. The qualitative evaluation of vocal fold movement was fixed vocal fold, reduced vocal fold movement and normal vocal fold movement, and the qualitative evaluation of glottic closure was glottic closure and glottic imperfection. The results were analyzed statistically. Results:The proportion of normal, reduced and fixed vocal fold motion in bilateral vocal fold paralysis group was significantly different from that in unilateral vocal fold paralysis group（P<0.05）, the composition of normal and reduced vocal fold motion in bilateral vocal fold paralysis group（47.70%） was significantly greater than that in unilateral vocal fold paralysis group（12.27%）. There was no significant difference between the proportion of glottic closure and glottic imperfecta in bilateral vocal fold paralysis group and unilateral vocal fold paralysis group（P<0.05）. The proportion of decreased vocal fold motion in superior laryngeal nerve paralysis group（50.00%） was higher than that in recurrent laryngeal nerve paralysis group（9.32%） and vagal nerve paralysis group（9.00%）. The proportion of decreased and fixed vocal fold motion in superior laryngeal nerve paralysis group, recurrent laryngeal nerve paralysis group and vagal nerve paralysis group was statistically significant（P<0.05）.There was no significant difference in glottic closure among the three groups（P<0.05）. Conclusion:Vocal fold movement characteristics of patients with laryngeal neurogenic injury were mainly vocal fold fixation, or normal or weakened vocal fold movement. There may be missed diagnosis of unilateral vocal fold paralysis in clinical practice. In half of the patients with superior laryngeal nerve palsy, vocal fold movement is characterized by vocal fold fixation.

Vocal fold electromyography in patients with endoscopic features of unilateral laryngeal paralysis.

<b><br>Introduction:</b> Electromyography (EMG) of the larynx provides information on the electrophysiological condition of laryngeal muscles and innervation. Integration of information obtained from the EMG exams with the clinical parameters as obtained by other methods for laryngeal assessment (endoscopy, perceptual and acoustic analysis, voice self-assessment) provides a multidimensional picture of dysphonia, which is of particular importance in patients with vocal fold (VF) mobility disorders accompanied by glottic insufficiency.</br> <b><br>Aim:</b> The aim of this study was to evaluate laryngeal EMG records acquired in subjects with unilateral vocal fold immobilization with signs of atrophy and glottic insufficiency.</br> <b><br>Material and methods:</b> From the available material of 74 EMG records of patients referred for the exam due to unilateral laryngeal paralysis, records of 17 patients with endoscopic features suggestive of complete laryngeal muscle denervation were selected. The EMG study of thyroarytenoid muscles of mobile and immobile VFs was evaluated qualitatively and quantitatively at rest and during volitional activity involving free phonation of vowel /e/ [ε].</br> <b><br>Results:</b> In all patients, the EMG records from mobile VFs were significantly different from those from immobile VFs. Despite endoscopic features of paralysis, no VF activity whatsoever was observed in as few as 2 patients so as to meet the neurophysiological definition of paralysis. In 88% of cases, electromyographic activity of the thyroarytenoid muscle was observed despite immobilization and atrophy of the vocal fold. In these patients, neurogenic type of record was observed with numerous high- -amplitude mobility units. On the basis of the results, quantitative features of EMG records indicative of paralysis and residual activity of the thyroarytenoid muscle were determined.</br> <b><br>Conclusions:</b> Qualitative and quantitative analysis of laryngeal EMG records provides detailed information on the condition of vocal fold muscles and innervation. EMG records of mobile vs immobile VFs differ significantly from each other. Endoscopic evaluation does not provide sufficient basis for the diagnosis of complete laryngeal muscle denervation.</br>.

Predominantly unilateral laryngomalacia in infants with unilateral vocal fold paralysis.

BACKGROUND: Neonatal unilateral vocal fold paralysis may arise iatrogenically, idiopathically, or in the context of an underlying neurologic disorder. Management is often supportive, focusing on diet modification to allow for safe oral feeding. We describe the clinical course of six infants with unilateral vocal fold paralysis who developed predominantly unilateral laryngomalacia ipsilateral to the affected vocal fold with associated severe respiratory symptoms and feeding difficulty. METHODS: Retrospective review of six infants with unilateral vocal fold paralysis and predominantly unilateral laryngomalacia. Charts were reviewed for etiology of vocal fold paralysis, presenting symptoms, operative details, postoperative course, and outcomes for breathing and swallowing. RESULTS: Etiology of vocal fold paralysis included cardiac surgery in four patients, intubation-related in one, and idiopathic in one. Presenting symptoms included increased work of breathing, stridor, feeding difficulty, respiratory failure requiring noninvasive respiratory support, and weak cry. All infants were on nasogastric tube feedings. Direct microlaryngoscopy with unilateral or predominantly unilateral (conservative contralateral aryepiglottic fold division) supraglottoplasty was performed. Stridor and work of breathing improved in all six patients within 1 week postoperatively. Oral feeding improved in three patients within 2 weeks. Three patients had persistent feeding impairment with improvement within one year. CONCLUSIONS: Predominantly unilateral laryngomalacia may arise in the context of unilateral vocal fold paralysis. Addressing the ipsilateral cuneiform collapse can improve breathing and feeding. This may be an under-described phenomenon and represents an additional reason to include the otolaryngologist early in the care of infants with suspected possible new unilateral vocal fold paralysis. Breathing and swallow can improve post-operatively, but feeding may remain limited by the vocal fold paralysis and any medical comorbidities. Ongoing follow-up and collaboration with speech-language pathology to optimize feeding are important.

[Clinical characteristics and efficacy of vocal fold epidermoid cysts coexisting with sulcus vocalis].

Objective: To investigate the clinical characteristics and voice outcomes after laryngeal microsurgery for vocal fold epidermoid cysts coexisting with sulcus vocalis. Methods: The clinical data of 115 vocal fold epidermoid cysts coexisting with sulcus vocalis patients in Shandong provincial ENT hospital, were retrospectively analyzed, including 49 males and 66 females, aged 17-70 years old, and the duration of hoarseness ranged from 6 months to 30 years. All patients underwent surgery through suspension laryngoscope and microscope under general anestgesia. Ninety-four patients were treated with microflap excision of sulcus vocalis, cyst wall, and contents.And 21 patients that occulted with mucosal bridges were applied mucosal bridges resection (2 cases) and mucosal bridges reconstruction (19 cases) respectively. Videolaryngoscopy, subjective voice evaluation (GRBAS), objective voice evaluation, and Voice Handicap Index(VHI) were performed before and after surgery. All patients underwent histopathologic examination and follow-up after the procedure. The preoperative acoustic parameters of patients with vocal fold epidermoid cysts coexisting with sulcus vocalis were compared with those of vocal fold mucus retention cysts and simple vocal fold epidermoid cysts by independent samples t-test. The patients were compared by paired t-test for preoperative and postoperative parameters. Results: Significant reduction or lack of mucosal waves were shown via videolaryngostroboscopy in all 115 cases.In addition, vascular changes including dilation, tortuousness, increased branches, and abrupt direction change were shown on the cystic area. Eighty-one patients were detected cysts and/or sulcus vocalis by preoperative laryngoscopy, and intraoperative microscopic findings in the remaining 34 patients. The intraoperative microscopic examination revealed a focal pouch-like deficit plunging into the vocal ligament or muscle. The deep surface of the mucosal bridges was sulcus vocalis, and that in 89 cysts was lined with caseous content. Histopathology demonstrated a cystic cavity structure lined with squamous epithelium and caseous keratin desquamation inside the cystic cavity. Four of 115 patients were lost at follow-up and excluded from the analysis of voice outcomes after surgery. There was no significant mucosal wave and the voice quality in all but 14 patients 1month after surgery. Except for the fundamental frequency and noise harmonic ratio, all other voice parameters[ G, R, B, A, VHI-10, jitter, shimmer, maximum phonatory time (MPT) ]showed a significant improvement 3 months after surgery(t=15.82, 20.82, 17.61, 7.30, 38.88, 7.84, 5.88, -6.26, respectively, P<0.05). Then mucosal waves and the voice quality were gradually improved and became steady in 6 months after surgery. The subjective and objective voice parameters[G, R, B, A, VHI-10, jitter, shimmer, noise to harmonic ratio(NHR), MPT], except for the fundamental frequency, were all significantly improved(t=23.47, 25.79, 18.37, 9.84, 54.45, 10.68, 8.07, 3.24, -9.08, respectively, P<0.05). In addition, there were 2 patients with no significant improvement after the operation. Steady function with no complications was observed during the 12 months (up to 3 years in 34 patients) follow-up period in 111 patients. Conclusion: Ruptured vocal fold epidermoid cysts can result in sulcus vocalis and mucosal bridges. Characteristics changes in preoperative videolaryngoscopy are effective diagnostic tools. The complete excision of the cyst wall and repair of the lamina propria can lead to satisfactory long-term effects.

Classification of laryngeal diseases including laryngeal cancer, benign mucosal disease, and vocal cord paralysis by artificial intelligence using voice analysis.

Voice change is often the first sign of laryngeal cancer, leading to diagnosis through hospital laryngoscopy. Screening for laryngeal cancer solely based on voice could enhance early detection. However, identifying voice indicators specific to laryngeal cancer is challenging, especially when differentiating it from other laryngeal ailments. This study presents an artificial intelligence model designed to distinguish between healthy voices, laryngeal cancer voices, and those of the other laryngeal conditions. We gathered voice samples of individuals with laryngeal cancer, vocal cord paralysis, benign mucosal diseases, and healthy participants. Comprehensive testing was conducted to determine the best mel-frequency cepstral coefficient conversion and machine learning techniques, with results analyzed in-depth. In our tests, laryngeal diseases distinguishing from healthy voices achieved an accuracy of 0.85-0.97. However, when multiclass classification, accuracy ranged from 0.75 to 0.83. These findings highlight the challenges of artificial intelligence-driven voice-based diagnosis due to overlaps with benign conditions but also underscore its potential.

Extrinsic Laryngeal Muscle Activity With Different Diameters and Water Depths in a Semi-Occluded Vocal Tract Exercise.

PURPOSE: Surface electromyography (sEMG) has been used to evaluate extrinsic laryngeal muscle activity during swallowing and phonation. In the current study, sEMG amplitudes were measured from the infrahyoid and suprahyoid muscles during phonation through a tube submerged in water. METHOD: The sEMG amplitude values measured from the extrinsic laryngeal muscles and the electroglottographic contact quotient (CQ) were obtained simultaneously from 62 healthy participants (31 men, 31 women) during phonation through a tube at six different depths (2, 4, 7, 10, 15, and 20 cm) while using two tubes with different diameters (1 and 0.5 cm). RESULTS: With increasing depth, the sEMG amplitude for the suprahyoid muscles increased in men and women. However, sEMG amplitudes for the infrahyoid muscles increased significantly only in men. Tube diameter had a significant effect on the suprahyoid sEMG amplitudes only for men, with higher sEMG amplitudes when phonating with a 1.0-cm tube. CQ values increased with submerged depth for both men and women. Tube diameter affected results such than CQ values were higher for men when using the wider tube and for women with the narrower tube. CONCLUSIONS: Vocal fold vibratory patterns changed with the depth of tube submersion in water for both men and women, but the patterns of muscle activation differed between the sexes. This suggests that men and women use different strategies when confronted with increased intraoral pressure during semi-occluded vocal tract exercises. In this study, sEMG provided insight into the mechanism for differences between vocally normal individuals and could help detect compensatory muscle activation during tube phonation in water for people with voice disorders.

Speaking without vocal folds using a machine-learning-assisted wearable sensing-actuation system.

Voice disorders resulting from various pathological vocal fold conditions or postoperative recovery of laryngeal cancer surgeries, are common causes of dysphonia. Here, we present a self-powered wearable sensing-actuation system based on soft magnetoelasticity that enables assisted speaking without relying on the vocal folds. It holds a lightweighted mass of approximately 7.2 g, skin-alike modulus of 7.83 × 105 Pa, stability against skin perspiration, and a maximum stretchability of 164%. The wearable sensing component can effectively capture extrinsic laryngeal muscle movement and convert them into high-fidelity and analyzable electrical signals, which can be translated into speech signals with the assistance of machine learning algorithms with an accuracy of 94.68%. Then, with the wearable actuation component, the speech could be expressed as voice signals while circumventing vocal fold vibration. We expect this approach could facilitate the restoration of normal voice function and significantly enhance the quality of life for patients with dysfunctional vocal folds.

Characteristics of lower airway parameters in an adult Asian population related to endotracheal tube design: a cadaveric study.

The risk of endotracheal tube (ETT) placement includes endobronchial intubation and subglottic injury. This study aimed to describe the lengths of lower airway parameters related to cuff location and vocal cord markings in different adult-sized ETTs. Eighty cadavers were examined for the lengths of the lower airway, including their correlations and linear regressions with height. Thirty adult-sized ETTs from seven different brands were examined for Mark-Cuff and Mark-Tip distances. The depth of ETT placement was simulated for each brand using vocal cord marking. The mean (standard deviation) lengths from the subglottis, trachea, vocal cord to mid- trachea, and vocal cord to carina were 24.2 (3.5), 97.9 (8.6), 73.2 (5.3), and 122.1 (9.0) mm, respectively. Airway lengths were estimated as: (1) subglottis (mm) = 0.173 * (height in cm) - 3.547; (2) vocal cord to mid-trachea (mm) = 0.28 * (height in cm) + 28.391. There were variations in the Mark-Cuff and Mark-Tip distances among different ETTs. In the simulation, endobronchial intubation ranged between 2.5 and 5% and the cuff in the subglottis ranged between 2.5 and 97.5%. In summary, the lower airway parameters were height-related. ETT placement using vocal cord marking puts the patient at a high risk of cuff placement in the subglottis.

Extramedullary plasmacytoma of the larynx - Case report.

Extramedullary plasmacytoma of the larynx is an extremely rare entity accounting for 0.04-0.45% of malignant tumours of the larynx. The objective of this clinical case report is to highlight the diagnosis and management of a unique case such as this. A 77-year-old gentleman presented with complaints of hoarseness for 1 year. Computed tomography image revealed a soft tissue mass lesion involving the right true vocal cord. Direct laryngoscopic biopsy was performed and subjected to histopathological examination, which showed collection of plasma cells. Immunohistochemistry confirmed the presence of Kappa and Lambda cells. Multiple myeloma (MM) was ruled out. The patient received radical intent radiation therapy using 3DCRT technique with a dose of 50Gy in 25# over 5 weeks. He experienced improvement in hoarseness on subsequent follow-up visits. At 1-year follow up, positron emission tomography computed tomography showed near total resolution of disease with no progression to MM. Radiation therapy alone is known to achieve good local control, recurrence free survival, and organ preservation in such cases.

Radiotherapy result of a case of Kaposi's sarcoma located on the vocal cord.

Kaposi's sarcoma (KS) is an angiogenic tumor. KS lesions frequently develop in the skin and oral cavity mucosa in the head and neck regions, and pure laryngeal localization is extremely rare. We reported a 64-year-old male patient without HIV, HBV, and HCV positivity presented with a hemangiomatous lesion detected incidentally in the right vocal cord. Biopsy was taken for histopathological and immunohistochemical evaluation. Examination revealed that spindle cells were of vascular origin and expressed HHV-8, a specific marker associated with Kaposi's sarcoma-associated herpesvirus. Positron emission tomography-computed tomography (PET/CT) demonstrated an increased fluorodeoxyglucose (FDG) uptake in the vocal cord. The patient was treated with a 30 Gy volumetric arc plan. Disease-free follow-up continues in the first year after low-dose definitive RT. This is the first case report of KS in the vocal cord in which the most detailed data about RT were shared.

How reliable is assessment of true vocal cord-arytenoid unit mobility in patients affected by laryngeal cancer? a multi-institutional study on 366 patients from the ARYFIX collaborative group.

PURPOSE: In clinical practice the assessment of the "vocal cord-arytenoid unit" (VCAU) mobility is crucial in the staging, prognosis, and choice of treatment of laryngeal squamous cell carcinoma (LSCC). The aim of the present study was to measure repeatability and reliability of clinical assessment of VCAU mobility and radiologic analysis of posterior laryngeal extension. METHODS: In this multi-institutional retrospective study, patients with LSCC-induced impairment of VCAU mobility who received curative treatment were included; pre-treatment endoscopy and contrast-enhanced imaging were collected and evaluated by raters. According to their evaluations, concordance, number of assigned categories, and inter- and intra-rater agreement were calculated. RESULTS: Twenty-two otorhinolaryngologists evaluated 366 videolaryngoscopies (total evaluations: 2170) and 6 radiologists evaluated 237 imaging studies (total evaluations: 477). The concordance of clinical rating was excellent in only 22.7% of cases. Overall, inter- and intra-rater agreement was weak. Supraglottic cancers and transoral endoscopy were associated with the lowest inter-observer reliability values. Radiologic inter-rater agreement was low and did not vary with imaging technique. Intra-rater reliability of radiologic evaluation was optimal. CONCLUSIONS: The current methods to assess VCAU mobility and posterior extension of LSCC are flawed by weak inter-observer agreement and reliability. Radiologic evaluation was characterized by very high intra-rater agreement, but weak inter-observer reliability. The relevance of VCAU mobility assessment in laryngeal oncology should be re-weighted. Patients affected by LSCC requiring imaging should be referred to dedicated radiologists with experience in head and neck oncology.

Restraining vocal fold vertical motion reduces source-filter interaction in a two-mass model.

Previous experimental studies suggested that restraining the vocal fold vertical motion may reduce the coupling strength between the voice source and vocal tract. In this study, the effects of vocal fold vertical motion on source-filter interaction were systematically examined in a two-dimensional two-mass model coupled to a compressible flow simulation. The results showed that when allowed to move vertically, the vocal folds exhibited subharmonic vibration due to entrainment to the first vocal tract acoustic resonance. Restraining the vertical motion suppressed this entrainment. This indicates that the vertical mobility of the vocal folds may play a role in regulating source-filter interaction.

Brainstem control of vocalization and its coordination with respiration.

Phonation critically depends on precise controls of laryngeal muscles in coordination with ongoing respiration. However, the neural mechanisms governing these processes remain unclear. We identified excitatory vocalization-specific laryngeal premotor neurons located in the retroambiguus nucleus (RAmVOC) in adult mice as being both necessary and sufficient for driving vocal cord closure and eliciting mouse ultrasonic vocalizations (USVs). The duration of RAmVOC activation can determine the lengths of both USV syllables and concurrent expiration periods, with the impact of RAmVOC activation depending on respiration phases. RAmVOC neurons receive inhibition from the preBötzinger complex, and inspiration needs override RAmVOC-mediated vocal cord closure. Ablating inhibitory synapses in RAmVOC neurons compromised this inspiration gating of laryngeal adduction, resulting in discoordination of vocalization with respiration. Our study reveals the circuits for vocal production and vocal-respiratory coordination.

Significance of Contusion at the Vocal Cord and Perivocal Cord Area in Cases of Non-intubated Death.

Every finding during a neck autopsy may be essential for accurately diagnosing and explaining the mechanism of death. In this prospective study in the Department of Forensic Medicine and Toxicology of Jordan University Hospital, 17 out of 95 neck autopsies revealed contusions of the laryngeal mucosa in the vocal or perivocal area. These contusions were found to be associated with various causes of death, including mechanical asphyxia (such as throttling, ligature strangulation, hanging, smothering, choking, plastic bag asphyxia, gagging, and inhalation of blood) and other causes (such as atypical drowning, carbon monoxide poisoning, head injury due to a road traffic accident, burns, electrocution, and brain edema). This study provides insight into the mechanisms of this important lesion and may contribute to a better understanding of the cause of death.

Dysphagia as a predictor of voice handicap and voice restoration in unilateral vocal fold immobility.

OBJECTIVE: Dysphagia is multifactorial in unilateral vocal fold immobility (UVFI). Severe dysphagia could indicate greater functional deficits in UVFI. The purpose of this study is to evaluate the association of dysphagia with the need for surgical voice restoration in patients with UVFI. STUDY DESIGN: Retrospective chart review. SETTING: Single-institution, tertiary referral center. METHODS: Records of UVFI patients from 2008 to 2018 were examined. Dysphagia severity was extracted from patient history. Etiology of UVFI and other relevant variables were analyzed to determine their association with dysphagia. Dysphagia severity and other clinical variables were then analyzed for their association with surgical voice restoration. RESULTS: Eighty patients met selection criteria out of 478 patients with UVFI. There was significant concordance between dysphagia severity extracted from patient history and patient-reported EAT-10 scores (R = 0.59, p = 0.000035). Patients' EAT-10 scores were correlated with VHI-10 scores (R = 0.45, p = 0.011). Severe dysphagia (p = 0.037), high VHI-10 score on presentation (p = 0.0009), and longer duration of hoarseness before presentation (p = 0.008) were associated with surgical voice restoration in UVFI patients. CONCLUSION: In this pilot study, severe dysphagia and increased voice handicap on presentation were associated with the need for surgical voice restoration in UVFI patients. Presenting dysphagia may be an additional variable for clinicians to consider for management of UVFI.

Sensitivity of Phonation Onset Pressure to Vocal Fold Stiffness Distribution.

Phonation onset is characterized by the unstable growth of vocal fold (VF) vibrations that ultimately results in self-sustained oscillation and the production of modal voice. Motivated by histological studies, much research has focused on the role of the layered structure of the vocal folds in influencing phonation onset, wherein the outer "cover" layer is relatively soft and the inner "body" layer is relatively stiff. Recent research, however, suggests that the body-cover (BC) structure over-simplifies actual stiffness distributions by neglecting important spatial variations, such as inferior-superior (IS) and anterior-posterior gradients and smooth transitions in stiffness from one histological layer to another. Herein, we explore sensitivity of phonation onset to stiffness gradients and smoothness. By assuming no a priori stiffness distribution and considering a second-order Taylor series sensitivity analysis of phonation onset pressure with respect to stiffness, we find two general smooth stiffness distributions most strongly influence onset pressure: a smooth stiffness containing aspects of BC differences and IS gradients in the cover, which plays a role in minimizing onset pressure, and uniform increases in stiffness, which raise onset pressure and frequency. While the smooth stiffness change contains aspects qualitatively similar to layered BC distributions used in computational studies, smooth transitions in stiffness result in higher sensitivity of onset pressure than discrete layering. These two general stiffness distributions also provide a simple, low-dimensional, interpretation of how complex variations in VF stiffness affect onset pressure, enabling refined exploration of the effects of stiffness distributions on phonation onset.

Acoustics and aerodynamic effects following glottal and infraglottal medialization in an excised larynx model.

OBJECTIVE: This study aimed to investigate the impact of the implant's vertical location during Type 1 Thyroplasty (T1T) on acoustics and glottal aerodynamics using excised canine larynx model, providing insights into the optimal technique for treating unilateral vocal fold paralysis (UVFP). METHODS: Measurements were conducted in six excised canine larynges using Silastic implants. Two implant locations, glottal and infraglottal, were tested for each larynx at low and high subglottal pressure levels. Acoustic and intraglottal flow velocity field measurements were taken to assess vocal efficiency (VE), cepstral peak prominence (CPP), and the development of intraglottal vortices. RESULTS: The results indicated that the implant's vertical location significantly influenced vocal efficiency (p = 0.045), with the infraglottal implant generally yielding higher VE values. The effect on CPP was not statistically significant (p = 0.234). Intraglottal velocity field measurements demonstrated larger glottal divergence angles and stronger vortices with the infraglottal implant. CONCLUSION: The findings suggest that medializing the paralyzed fold at the infraglottal level rather than the glottal level can lead to improved vocal efficiency. The observed larger divergence angles and stronger intraglottal vortices with infraglottal medialization may enhance voice outcomes in UVFP patients. These findings have important implications for optimizing T1T procedures and improving voice quality in individuals with UVFP. Further research is warranted to validate these results in clinical settings.

An Integrated Experimental-Computational Study of Vocal Fold Vibration in Type I Thyroplasty.

Subject-specific computational modeling of vocal fold (VF) vibration was integrated with an ex vivo animal experiment of type 1 thyroplasty to study the effect of the implant on the vocal fold vibration. In the experiment, a rabbit larynx was used to simulate type 1 thyroplasty, where one side of the vocal fold was medialized with a trans-muscular suture while the other side was medialized with a silastic implant. Vocal fold vibration was then achieved by flowing air through the larynx and was filmed with a high-speed camera. The three-dimensional computational model was built upon the pre-operative scan of the laryngeal anatomy. This subject-specific model was used to simulate the vocal fold medialization and then the fluid-structure interaction (FSI) of the vocal fold. Model validation was done by comparing the vocal fold displacement with postoperative scan (for medialization), and by comparing the vibratory characteristics with the high-speed images (for vibration). These comparisons showed the computational model successfully captured the effect of the implant and thus has the potential for presurgical planning.

The Long Term Results of Hyaluronic Acid/Dextranomer Injection Laryngoplasty in Unilateral Vocal Fold Paralysis.

OBJECTIVE: This study was conducted to present the long-term functional outcomes of injection laryngoplasty (IL) with hyaluronic acid/dextranomer (HA/D) in unilateral vocal fold paralysis (UVFP). METHODS: A total of 40 patients who underwent HA/D injection for UVFP were enrolled. The acoustic analysis of the voice was evaluated with jitter percentage, shimmer percentage, maximum phonation time, harmonics-to-noise ratio, and fundamental frequency. The psychosocial effect of the voice was determined using the Voice Handicap Index-10. Fiberoptic endoscopic evaluation of swallowing was performed and 2 scales were used for quantification: a modified penetration-aspiration scale and a dysphagia score. All measurements were performed at preoperative day and postoperative months 1, 6, and 24. RESULTS: A statistically significant improvement was observed for all of the evaluated parameters except the maximum phonation time for postoperative months 1, 6, and 24 (P < .05). In the evaluation of the maximum phonation time, although there was a significant improvement for the postoperative months 1 and 6, no significant difference was observed between the postoperative 24th month and the preoperative value. CONCLUSIONS: HA/D injection laryngoplasty is an effective method both in the short- and long-term to improve voice and swallowing functions in patients with UVFP.