Effects of lateral manual compression upon glottic incompetence: objective evaluations

Excised human larynx in N-vinyl-2-pyrrolidone-embalmed cadavers can produce voiced sound by pliable vocal fold vibration

Tissue-hardening effect and health-hazard issue of formaldehyde (FA) have long been a great disadvantage of this conventional fixative in anatomical research. We recently developed a FA-free embalming method for cadavers which utilizes N-vinyl-2-pyrrolidone (NVP) and enables assessment of motion kinetics by maintaining the softness of embalmed tissue. By assessing the feasibility of NVP-embalmed tissue to mimic vocalization, this study aimed to prove the potential of embalmed cadavers, which have previously been used only for the understanding of anatomical morphology, for the assessment of precise motion physiology in the human body. Ten cadavers embalmed in NVP (n = 6) and FA (n = 4) were incorporated in this study. Excised larynges underwent experimental phonation to mimic vocalization with fast and pliable vibration of vocal folds. High-speed digital imaging was utilized for the assessment of vocal fold vibration. Furthermore, acoustic analysis of the voiced sound, and reproducibility examination were also performed. Regular vocal fold vibrations successfully produced voiced sounds during experimental phonation using NVP-embalmed larynges. The vibratory frequency, vibration amplitude, and stretch rate of the vocal folds were comparable to those of living humans. Six months after the first experiment, the vocal parameters were reproduced, to suggest the long-term preservation potential of our NVP-embalming technique. On the other hand, neither voiced sound nor vocal fold vibration were observed in FA-embalmed larynges. This novel embalming technique could pioneer the next era to utilize embalmed cadavers for the examination of motion physiology in the human body.

Pre and post operative voice analysis after medialization thyroplasty in cases of unilateral vocal fold paralysis

The present study was undertaken to assess the efficacy of medialization thyroplasty on outcome of voice quality in vocal cord paralysis by analyzing the voice. A total 19 patients with vocal cord paralysis of different etiologies were included in the study. Preoperative voice analysis was done by voice recordings, GRBAS score, maximum phonation time (MPT) and acoustic analysis using Dr Speech software (University version 4.0) using habitual fundamental frequency (F0), jitter %, shimmer % and normalized noise energy (NNE) as parameters. 18 patients underwent type 1 or medialization thyroplasty alone and 1 patient had undergone medialization thyroplasty along with arytenoids adduction. Post operative voice analysis was done using same parameters. There was post operative improvement of voice in 16 patients whereas 3 patients showed no significant improvement. Mean preoperative MPT was 4.8947 s and post operative was 13 s. Mean preoperative GRBAS score was 76.1579 and post operative was 30. On acoustic analysis, mean preoperative habitual fundamental frequency (F0), jitter %, shimmer % and NNE was 278.16 Hz, 1.7, 6.81 and 1.81 dB respectively whereas post operative mean was 132.37 Hz, 0.41, 1.65 and 123.38 dB respectively. Thyroplasty offers good voice outcome in patients of uncompensated vocal cord paralysis. Improvement can be documented in terms of perceptual evaluation of voice and acoustic analysis as well as maximum phonation time in addition to voice recording.

Paralisia unilateral de prega vocal: associação e correlação entre tempos máximos de fonação, posição e ângulo de afastamento

A paralisia de prega vocal (PPV) decorre da lesão do nervo vago ou de seus ramos, podendo levar a alterações das funções que requerem o fechamento glótico. O tempo máximo de fonação (TMF) é um teste aplicado rotineiramente em pacientes disfônicospara avaliar a eficiência glótica e freqüentemente utilizado em casos de PPV, cujos valores encontram-se diminuídos. A classificação clínica clássica da posição da prega vocal paralisada em mediana, para-mediana, intermediária e em abdução ou cadavérica tem sido objeto de controvérsias. OBJETIVO: Verificar a associação e correlação entre os TMF e posição da prega vocal paralisada (PVP), TMF e ângulo de afastamento da PVP, medir o ângulo de afastamento da linha média das diferentes posições da PVP e correlacioná-lo com a sua classificação clínica FORMA DE ESTUDO: Clínico retrospectivo. MATERIAL E MÉTODO: Foram revisados os prontuários e analisados os exames videoendoscópicos de 86 indivíduos com paralisia de prega vocal unilateral e medido o ângulo de afastamento da PVP por meio de um programa computadorizado. RESULTADOS: A associação e correlação entre os TMF em cada posição assumida pela PVP têm significância estatística somente para /z/ na posição mediana. A associação e correlação entre TMF com ângulo de afastamento da PVP guardam relação para /i/, /u/. Ao associar e correlacionar medidas de ângulo com posição observa-se significância estatística em posição de abdução. CONCLUSÕES: Neste estudo não foi possível determinar as posições assumidas pela PVP por meio dos TMF nem correlacioná-las com medidas do ângulo.

[Preoperative evaluation in thyroplasty: the laryngeal lateral compression]

Thyroplasty type I has provided significant improvement to the treatment of patients with glottal incompetence. It is essential that patients be preoperatively evaluated using objective criteria. Laryngeal manual compression test are manipulations of the thyroid and cricoid cartilages that result in modifications of the position of the vocal folds. The most valuable laryngeal manual compression test for patients with glottal insufficiency is the lateral compression test. When this test results in a preoperative improvement in voice suggest that surgery will be successful. In this paper we present the objective evaluation of the effects of lateral compression test upon glottic incompetence by means of narrow band power spectrum analysis.

Arytenoid adduction and medialization laryngoplasty

Arytenoid adduction and medialization laryngoplasty have become the mainstay of static surgical rehabilitation of the larynx after vocal fold paralysis. The rationale for considering one versus a combination of the two procedures has not been well addressed. This article outlines the basic science of the procedures and the clinical technical modifications necessary to make the surgery easier.

Mechanical and Dynamic Aspects of Voice Production as Related to Voice Therapy and Phonosurgery

Laryngeal framework surgery can change the position and tension of the vocal folds safely without direct surgical intervention in the vocal fold proper. Some 23 years of experience with phonosurgery have proved its usefulness in treating dysphonia related to unilateral vocal fold paralysis, vocal fold atrophy, and pitch-related dysphonias. Meanwhile, much information about the mechanism of voice production has been obtained through intraoperative findings of voice and fiberscopic examination of the larynx. Based on such knowledge together with information obtained through model experiments, the human vocal organ was reconsidered mainly from the mechanical view point, and the roles of voice therapy and singing pedagogy were discussed in relation to phonosurgery. The vocal organ may not be an ideal musical organ and is rather vulnerable, but its potential is enormous.

Vocal mechanics as the basis for phonosurgery

OBJECTIVE

A number of modifications in laryngoplastic phonosurgery have recently been proposed. This report is intended to clarify the concept on which the surgery should be based, vocal mechanics, for further rational development of the surgery.

STUDY DESIGN

The results of various previous surgeries were compared. In an attempt to elucidate what makes the difference in the results, simulation of voice production was conducted with the use of excised larynges.

METHODS

Excised larynges were mounted on a tube so as to be blown from below. Experimental variables in the model included the glottal area initially set, stiffness of the vocal folds, and subglottal pressure. The conditions under which the voice became hoarse were examined.

RESULTS

The voice became hoarse under the following major conditions: 1) the initial glottal area exceeded a certain value, 2) stiffness was too high, and 3) the glottis was too tightly closed. Clinical representation for each condition was made, particularly for excessively tight glottal closure such as in spasmodic dysphonia. A new type of surgical treatment for spasmodic dysphonia, lateralization thyroplasty, was briefly reported, which restored the voice to normal without recurrence for 1 year at the time of this writing.

CONCLUSIONS

A potential new type of laryngoplastic phonosurgery should be conformed to the mechanics of voice production. In treating dysphonia, it is often necessary to switch from etiologic or radical treatment, if infertile, to symptomatic treatment instead, at the level of mechanics.

Mechanical and dynamic aspects of voice production as related to voice therapy and phonosurgery

Laryngeal framework surgery can change the position and tension of the vocal folds safely without direct surgical intervention in the vocal fold proper. Some 23 years of experience with phonosurgery have proved its usefulness in treating dysphonia related to unilateral vocal fold paralysis, vocal fold atrophy, and pitch-related dysphonias . Meanwhile, much information about the mechanism of voice production has been obtained through intraoperative findings of voice and fiberscopic examination of the larynx . Based on such knowledge together with information obtained through model experiments, the human vocal organ was reconsidered mainly from the mechanical view point, and the roles of voice therapy and singing pedagogy were discussed in relation to phonosurgery. The vocal organ may not be an ideal musical organ and is rather vulnerable, but its potential is enormous.

Omohyoid muscle transposition for the treatment of bowed vocal fold

Imperfect glottal closure is usually the most important factor causing dysphonia in patients with bowing of the vocal folds. We have performed laryngeal framework surgery, which allows the medialization of the vocal folds from the outside without creating any scar tissue on them. Over the past 6 years, however, we encountered three cases with marked bowing of the vocal folds that could not be cured by laryngeal framework surgery alone. We used an open laryngeal procedure in these cases, even though such procedures had been considered contraindicated in the treatment of hoarseness. After performing a laryngofissure, we made a small pocket beneath the vocal fold mucosa at the anterior commissure. The superiorly based omohyoid muscle flap was then transposed into the mucosal pocket and sutured to the vocal process. This procedure should be considered an option in treating highly bowed vocal folds.

Vocal fold atrophy and its surgical treatment

The effectiveness of surgical treatment for vocal fold atrophy of various causes was examined. Type I thyroplasty was performed on 31 patients with vocal fold atrophy, often bilaterally and occasionally combined with type III thyroplasty. Of these 31 patients, 3 patients underwent the operation twice, for a total of 34 operations. The surgery was found to be effective in improving the voice quality and the ease of phonation. When a scar or sulcus was present, the results were not as satisfactory. The intraoperative decision-making process as to which procedure to perform is extremely important for achieving an optimal voice, and should be based on the intraoperative voice quality, fiberoptic findings, and manual tests. In operations for vocal fold atrophy in which the vocal folds are mobile, a silicone shim should be firmly fixed to prevent migration. Overcorrection is generally recommended. No complications were encountered. It was often the increased ease of phonation rather than the improved voice quality that patients appreciated after surgery.

Thyroplasty: a new approach

A new type of thyroplasty implant (prosthesis) has been designed to be used of a surgical operation that accomplishes medial displacement of a paralyzed vocal cord. The implant is inserted through a rectangular window fashioned in the thyroid lamina on the side of the vocal cord paralysis. Instruments for measuring the location and outline of the window in the thyroid lamina are presented. A thyroplasty saw blade is introduced. By using this blade, a window of precise measurement can be constructed without injury to the underlying perichondrium. The implant is constructed from a biocompatible, medical-grade polymer. Four sizes each are available for the male and female larynges. The proper-size implant can be selected with a measuring device. It is not necessary to alter the implant at the time of surgery; it snaps into place and suturing is not necessary. Once the implant is inserted, its medial or lateral displacement is not possible; on the other hand, the implant can be easily removed if vocal cord function returns, or if a change to a different-size implant is indicated. The design of the implant will close the posterior commissure.