Multiparameter analysis of titanium vocal fold medializing implant in an excised larynx model

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 Ex-vivo Model Examining Acoustics and Aerodynamic Effects Following Medialization With and Without Arytenoid Adduction

OBJECTIVES/HYPOTHESIS

Quantify differences in acoustics and intraglottal flow fields between Thyroplasty Type 1 (TT1) with and without arytenoid adduction (AA) using excised canine larynx model.

STUDY DESIGN

Basic science experiments using excised larynges.

METHODS

Surgical procedures were implemented in eight excised canine larynges. Acoustics and intraglottal flow measurements were taken at low and high subglottal pressures in each experimental setup.

RESULTS

In all larynges, vocal efficiency (VE) and cepstrum peak prominence (CPP) were higher, and the mean phonatory flow rate was lower in TT1 with AA than without AA. The glottal asymmetry is reduced with AA and promotes the formation of stronger vortices in the glottal flow during the closing phase of the vibrating folds.

CONCLUSIONS

Findings suggest a clear acoustic and aerodynamic benefit to the addition of AA when performing TT1. It shows significant improvement in CPP, translating to decreased breathiness and dysphonia and increased VE, leading to easier and more sustainable phonation. Stronger intraglottal vortices are known to be correlated with the loudness of voice produced by phonation.

LEVEL OF EVIDENCE

N/A Laryngoscope, 133:621-627, 2023.

Active and Passive Bioimplants for Vocal Fold Paralysis

Vocal fold paralysis is one of the diseases that particularly affect quality of life. While unilateral paralysis leads to glottis closure insufficiency and hoarseness, bilateral paralysis compromises respiration and limits the exercise tolerance. Bioimplants have been used to treat persistent paralysis for over 100 years. The spectrum ranges from autologous tissue transfer and resorbable or permanent injection materials to composite thyroplasty implants and active electrical implants for neurostimulation of the larynx. If bioimplants are used in accordance with the recommendations, the quality of life of affected patients can be significantly improved today.

Glass ionomer application for vocal fold augmentation: Histopathological analysis on rabbit vocal fold

OBJECTIVES/HYPOTHESIS

The aim of this study was to investigate the use of glass ionomer cement (GIC) as an injection material for vocal fold augmentation and to evaluate the biocompatibility of the material.

STUDY DESIGN

Ten adult New Zealand rabbits were used.

METHODS

Under general anesthesia, 0.1-cc GIC was injected to one vocal fold and the augmentation of vocal fold was observed. No injection was applied to the opposite side, which was accepted as the control group. The animals were sacrificed after 3 months and the laryngeal specimens were histopathologically evaluated.

RESULTS

The injected and the noninjected control vocal folds were analyzed. The GIC particles were observed in histological sections on the injected side, and no foreign body giant cells, granulomatous inflammation, necrosis, or marked chronic inflammation were detected around the glass ionomer particles. Mild inflammatory reactions were noticed in only two specimens. The noninjected sides of vocal folds were completely normal.

CONCLUSION

The findings of this study suggest that GIC is biocompatible and may be further investigated as an alternative injection material for augmentation of the vocal fold. Further studies are required to examine the viscoelastic properties of GIC and the long-term effects in experimental studies.

LEVEL OF EVIDENCE

NA.

Phonatory effects of type I thyroplasty implant shape and depth of medialization in unilateral vocal fold paralysis

OBJECTIVES/HYPOTHESIS

Medialization thyroplasty (MT) is commonly used to treat glottic insufficiency. In this study, we investigated the phonatory effects of MT implant medialization depth and medial surface shape.

METHODS

Recurrent laryngeal nerve (RLN) and vagal paralysis were simulated in an in vivo canine. A type 1 MT was performed using a silicone elastomer implant with variable medialization depths and medial surface shapes: rectangular, V-shaped, divergent, and convergent. The effects on phonation onset flow/pressure relationships and acoustics were measured.

RESULTS

Increasing depth of medialization led to improvements in fundamental frequency (F0) range and normalization of the slope of pressure/flow relationship toward baseline activation conditions. The effects of implant medial shape also depended on depth of medialization. Outcome measures were similar among the implants at smaller medialization depths. With large medialization depths and vagal paralysis conditions, the divergent implant maintained pressure/flow relationship closer to baseline. The vagal paralysis conditions also demonstrated decreased fundamental frequency range and worse flow/pressure relationship compared to RLN paralysis.

CONCLUSIONS

The depth and medial shape of a medialization laryngoplasty (ML) implant significantly affect both the F0 range and aerodynamic power required for phonation. These effects become more notable with increasing depth of medialization. The study also illustrates that ML is less effective in vagal paralysis compared to RLN paralysis.

LEVEL OF EVIDENCE

N/A.

Comparison of the use of silastic with titanium prefabricated implant in type I thyroplasty✩✩Please cite this article as: Malik A, Ramalingam WVBS, Nilakantan A, Nair S, Ramesh AV, Raj P. Comparison of the use of silastic with titanium prefabricated implant in type I thyroplasty. Braz J Otorhinolaryngol. 2014;80:156-60

Introdução

A tireoplastia tipo I é o tratamento de escolha nas paralisias unilaterais das pregas vocais que não se recuperam espontaneamente.

Objetivos

Comparar o uso de implante de Silastic® com o uso de titânio pré-fabricado TVFMI® (Titanium Vocal Fold Medializing Implant) na tireoplastia tipo I para o tratamento da paralisia unilateral das pregas vocais com relação à melhora subjetiva e objetiva da voz, às alterações endoscópicas nas pregas vocais, ao tempo de cirurgia e à relação custo-benefício.

Método

Trata-se de um estudo prospectivo com 40 pacientes portadores de paralisia unilateral das pregas vocais submetidos à tireoplastia tipo I com implante de silastic® ou TVFMI®. A avaliação e comparação estatística foram realizadas antes e quatro semanas depois da cirurgia por meio de videolaringoscopia, estroboscopia, análise perceptiva (escala GRBAS-Grade, Roughness, Breathiness, Asthenia, Strain) e subjetiva (IDV-índice de desvantagem vocal) da voz e avaliação eletroglotográfica e avaliação acústica computadorizada. Também foram observados o tempo de cirurgia e o custo do implante.

Resultados

Embora os dois implantes mostrem melhora na qualidade da voz após a tireoplastia, o TVFMI® teve um resultado ligeiramente melhor na análise objetiva da voz. O TVFMI® levou menos tempo de cirurgia para ser inserido, porém foi mais caro.

Conclusão

O TVFMI® poderá ser preferencial na tireoplastia de medialização, já que possui melhores resultados vocais e leva menos tempo de cirurgia, porém é mais caro que o implante de Silastic®.

© 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Publicado por Elsevier Editora Ltda. Todos os direitos reservados.

Experiments on Analysing Voice Production: Excised (Human, Animal) and In Vivo (Animal) Approaches

Experiments on human and on animal excised specimens as well as in vivo animal preparations are so far the most realistic approaches to simulate the in vivo process of human phonation. These experiments do not have the disadvantage of limited space within the neck and enable studies of the actual organ necessary for phonation, i.e., the larynx. The studies additionally allow the analysis of flow, vocal fold dynamics, and resulting acoustics in relation to well-defined laryngeal alterations.

PURPOSE OF REVIEW

This paper provides an overview of the applications and usefulness of excised (human/animal) specimen and in vivo animal experiments in voice research. These experiments have enabled visualization and analysis of dehydration effects, vocal fold scarring, bifurcation and chaotic vibrations, three-dimensional vibrations, aerodynamic effects, and mucosal wave propagation along the medial surface. Quantitative data will be shown to give an overview of measured laryngeal parameter values. As yet, a full understanding of all existing interactions in voice production has not been achieved, and thus, where possible, we try to indicate areas needing further study.

RECENT FINDINGS

A further motivation behind this review is to highlight recent findings and technologies related to the study of vocal fold dynamics and its applications. For example, studies of interactions between vocal tract airflow and generation of acoustics have recently shown that airflow superior to the glottis is governed by not only vocal fold dynamics but also by subglottal and supraglottal structures. In addition, promising new methods to investigate kinematics and dynamics have been reported recently, including dynamic optical coherence tomography, X-ray stroboscopy and three-dimensional reconstruction with laser projection systems. Finally, we touch on the relevance of vocal fold dynamics to clinical laryngology and to clinically-oriented research.

Preliminary investigation of adjustable balloon implant for type I thyroplasty

OBJECTIVE

We present the adjustable balloon implant (ABI), a novel implant to be used in type I thyroplasty for the treatment of vocal fold paralysis. The ABI offers the same medialization provided by other implants, but can easily be catered to individual patient anatomy as well as modified postoperatively without the need for a revision thyroplasty.

STUDY DESIGN

Repeated measures with each larynx serving as its own control.

METHODS

Medialization thyroplasty (MT) with the ABI was performed on five excised canine larynges. Mucosal wave, aerodynamic, and acoustic parameters were measured for three conditions: normal; right vocal fold paralysis; and paralysis with the ABI.

RESULTS

Insertion of the ABI resulted in significant decreases in both phonation threshold pressure and phonation threshold flow. Perturbation parameters of percent jitter and percent shimmer were also significantly decreased and restored to normal levels. Signal-to-noise ratio was significantly increased to the normal level as well. The mucosal wave was preserved after implant insertion.

CONCLUSIONS

This preliminary experiment showing significant improvements in aerodynamic and acoustic parameters demonstrates the potential of the ABI as a thyroplasty implant. Effective medialization and preservation of the mucosal wave combined with postoperative adjustability makes it a potentially valuable clinical device.

Optimal arytenoid adduction based on quantitative real-time voice analysis

HYPOTHESIS

The optimal degree of arytenoid rotation for arytenoid adduction (AA) can be determined using quantitative real-time voice analysis.

STUDY DESIGN

Repeated measures with each larynx serving as its own control.

METHODS

Unilateral vocal fold paralysis (VFP) was modeled in five excised canine larynges. Medialization laryngoplasty (ML) was performed, followed by AA. The optimal degree of arytenoid rotation was determined using real-time measurements of vocal efficiency (V(E) ), percent jitter, and percent shimmer. After the optimal degree of rotation was determined, the arytenoid was hypo- and hyperrotated 10% ± 2% of the optimal angle to mimic hypoadducted and hyperadducted states. Aerodynamic, acoustic, and mucosal wave measurements were recorded.

RESULTS

Mean optimal angle of arytenoid adduction was 151.4 ± 2.5°. V(E) differed significantly across experimental conditions (P = .003). Optimal AA produced the highest V(E) of any treatment, but this value did not reach that produced in the normal condition. Percent jitter (P < .001) and percent shimmer (P < .001) differed across groups and were lowest for optimal AA. Mucosal wave amplitude of the normal (P = .001) and paralyzed fold (P = .043) differed across treatments. Amplitude of both folds was highest for optimal AA.

CONCLUSIONS

V(E) and perturbation parameters were sensitive to the degree of arytenoid rotation. Using real-time voice analysis may aid surgeons in determining the optimal degree of arytenoid rotation when performing AA. Testing this method in patients and determining if optimal vocal outcomes are associated with optimal respiratory and swallowing outcomes will be essential to establishing clinical viability.