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Effect of inferior surface angle on the self-oscillation of a computational vocal fold model.

ABSTRACT: Geometry of the human vocal folds strongly influences their oscillatory motion. While the effect of intraglottal geometry on phonation has been widely investigated, the study of the geometry of the inferior surface of the vocal folds has been limited. In this study the way in which the inferior vocal fold surface angle affects vocal fold vibration was explored using a two-dimensional, self-oscillating finite element vocal fold model. The geometry was parameterized to create models with five different inferior surface angles. Four of the five models exhibited self-sustained oscillations. Comparisons of model motion showed increased vertical displacement and decreased glottal width amplitude with decreasing inferior surface angle. In addition, glottal width and air flow rate waveforms changed as the inferior surface angle was varied. Structural, rather than aerodynamic, effects are shown to be the cause of the changes in model response as the inferior surface angle was varied. Supporting data including glottal pressure distribution, average intraglottal pressure, energy transfer, and flow separation point locations are discussed, and suggestions for future research are given.

SUBMITTER: Smith SL

PROVIDER: S-EPMC3356320 | biostudies-other | 2012 May

REPOSITORIES: biostudies-other

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Identification of geometric parameters influencing the flow-induced vibration of a two-layer self-oscillating computational vocal fold model.

Project description:Simplified models have been used to simulate and study the flow-induced vibrations of the human vocal folds. While it is clear that the models' responses are sensitive to geometry, it is not clear how and to what extent specific geometric features influence model motion. In this study geometric features that played significant roles in governing the motion of a two-layer (body-cover), two-dimensional, finite element vocal fold model were identified. The model was defined using a flow solver based on the viscous, unsteady, Navier-Stokes equations and a solid solver that allowed for large strain and deformation. A screening-type design-of-experiments approach was used to identify the relative importance of 13 geometric parameters. Five output measures were analyzed to assess the magnitude of each geometric parameter's effect on the model's motion. The measures related to frequency, glottal width, flow rate, intraglottal angle, and intraglottal phase delay. The most significant geometric parameters were those associated with the cover--primarily the pre-phonatory intraglottal angle--as well as the body inferior angle. Some models exhibited evidence of improved model motion, including mucosal wave-like motion and alternating convergent-divergent glottal profiles, although further improvements are still needed to more closely mimic human vocal fold motion.

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Dynamic imaging of vocal fold oscillation with four-dimensional optical coherence tomography.

Project description:Objectives/hypothesisOptical coherence tomography (OCT) can provide high-resolution ( approximately 10-15 microm/pixel) images of vocal fold microanatomy, as demonstrated previously. We explored physiologically triggered Fourier-domain OCT for imaging vocal folds during phonation. The goal is to visualize dynamic histological cross sections and four-dimensional data sets where multiple planes are displayed in synchronized motion. If feasible, this approach could be a useful research tool and spur development of new clinical instrumentation.Study designA Fourier-domain, triggered OCT system was created and tested in experiments on excised calf larynges to obtain preliminary observations and characterize important factors affecting image quality.MethodsLarynges were imaged during phonation driven by warm, humidified air. A subglottal pressure signal was used to synchronize the OCT system with the phonatory cycle. Image sequences were recorded as functions of anatomical location or subglottal pressure. Implant materials were also imaged during vibration, both in isolation and after injection into a vocal fold.ResultsOscillations of epithelium and lamina propria were observed, and parameters such as shape, amplitude, and velocity of the vocal fold mucosal waves were found to be measurable. Ripples of mucosal wave as small as 100 microm in vertical height were clearly visible. Internal strain was also observed in normal and implanted vocal folds.ConclusionsFour-dimensional OCT of the vocal fold may help to more directly relate biomechanics to anatomy and disease. It may also be useful for assaying the functional rheology of implants in the context of real tissue. With further development, this technology has potential for clinical endoscopic application.

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Age-dependent treatment effect of vocal fold steroid injection for benign vocal fold lesions.

Project description:ObjectiveBenign vocal fold lesions (BVFLs) cause voice disorders and impair social life. Recently, office-based vocal fold steroid injection (VFSI) has gained attention as a minimally invasive treatment for BVFLs. This study aimed to analyze the age-dependent treatment effect of VFSI and to clarify the indications for treatment.MethodsIn this retrospective cohort study, a total of 83 patients with BVFLs were treated with a similar regimen of VFSI. Three or four months after the injection, age-dependent phonological functions were evaluated. The differences between pre- and post-treatment findings were analyzed using the Wilcoxon matched-pair signed-rank test, and the correlation between patient age and improvement rates were determined by Pearson's correlation coefficient.ResultsImprovement in voice handicap index (VHI), which was the primary endpoint, was observed. Subjective and objective voice quality measurements also showed significant improvements. Subgroup analyses revealed that there was no age-related difference in the improvement of voice quality and that there was no improvement in aerodynamic effect in patients over 45 years of age.ConclusionThis study clarified the age-dependent treatment effect of VFSI and provided the important suggestion of establishing indication criteria for BVFLs. The study results provided clarity on the indication criteria of VFSI and served as an important indicator for tailoring treatment to patients' needs.Level of evidence4.

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Expression data from rat vocal fold at different periods after vocal fold injury

Project description:Vocal cord healing is a dynamic process, and many genes and proteins are involved, which play varying roles at different regeneration stages after injury. Previous studies have shown that inflammatory responses occur at the early stage of vocal cord injury, where the fibroblasts proliferate exuberantly with intensive secretion and deposition of ECM. These activities reach the peak at 3-7 days and their intensity begins to decline 15 days later. A study based on the dermal system has shown that ECM remodeling during the repair of injury can last for several months. However, few studies have been conducted as to the dynamic changes of gene expressions and signaling pathway during the healing process of vocal cord injury. Plotting these changes will facilitate the understanding about the physiological changes during healing and the identification of key time points and target genes in fibrosis formation.

2019-10-26 | GSE139383 | GEO

Vocal fold leukoplakia recurrence risk model.

Project description:The paper aims to define the variables that elevate the risk of VFL recurrence after adequate primary treatment, and to present the Recurrence Risk Model with practical conclusions to handle pVFL and rVFL. Out of 207 patients with primary vocal fold leukoplakia (pVFL), in 41 (19.8%) recurrent VFL (rVFL) was diagnosed. All patients were assessed by using a trans-nasal flexible video-endoscope using white light, and NBI. The primary measure of our study was to investigate whether morphological features of pVFL in WL, vascular pattern in NBI, and primary histological findings could predict VFL recurrence. To create a model of risk factors, two methods were used: logistic regression and a conditional inference decision tree. The study showed smoking was the factor that significantly and most strongly increased the likelihood of rVFL, as well as the older age groups have a greater odds of rVFL. Types IV, V and VI, according to Ni 2019 classification, were associated with a significantly higher risk of rVFL. The algorithm combining patients' dependent variables and the combination of two classifications improves the predictive value of the presented VFL Recurrence Risk Model.

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Influence of subglottic stenosis on the flow-induced vibration of a computational vocal fold model.

Project description:The effect of subglottic stenosis on vocal fold vibration is investigated. An idealized stenosis is defined, parameterized, and incorporated into a two-dimensional, fully-coupled finite element model of the vocal folds and laryngeal airway. Flow-induced responses of the vocal fold model to varying severities of stenosis are compared. The model vibration was not appreciably affected by stenosis severities of up to 60% occlusion. Model vibration was altered by stenosis severities of 90% or greater, evidenced by decreased superior model displacement, glottal width amplitude, and flow rate amplitude. Predictions of vibration frequency and maximum flow declination rate were also altered by high stenosis severities. The observed changes became more pronounced with increasing stenosis severity and inlet pressure, and the trends correlated well with flow resistance calculations. Flow visualization was used to characterize subglottal flow patterns in the space between the stenosis and the vocal folds. Underlying mechanisms for the observed changes, possible implications for human voice production, and suggestions for future work are discussed.

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Expression data from rat vocal fold at different periods after vocal fold injury (miRNA)

Project description:Vocal cord healing is a dynamic process, and many genes and proteins are involved, which play varying roles at different regeneration stages after injury. Previous studies have shown that inflammatory responses occur at the early stage of vocal cord injury, where the fibroblasts proliferate exuberantly with intensive secretion and deposition of ECM. These activities reach the peak at 3-7 days and their intensity begins to decline 15 days later. A study based on the dermal system has shown that ECM remodeling during the repair of injury can last for several months. However, few studies have been conducted as to the dynamic changes of gene and microRNA expressions during the healing process of vocal cord injury. Plotting these changes will facilitate the understanding about the physiological changes during healing and the identification of key time points and target genes and microRNAs in fibrosis formation.

2020-03-25 | GSE147473 | GEO

Transcription in wounded rat vocal folds and vocal fold fibroblasts

Project description:We used microarrays to characterize transcriptome profiles of rat vocal fold tissue following surgical injury (vs. naive tissue); rat vocal fold fibroblasts harvested from scar tissue at the 60 d time point (vs. naive fibroblasts); rat vocal fold scar fibroblasts treated with siRNA against the collagen chaperone protein rat gp46 (vs. scramble siRNA). Adult Fischer 344 rat vocal fold tissue was harvested at 3, 14, and 60 days following surgical injury (control = age-matched naive tissue); rat vocal fold scar fibroblasts were obtained via explant culture of tissue obtained 60 days following surgical injury and harvested at 80% confluence during passage 1 (control = age-matched naive rat vocal fold fibroblasts); rat vocal fold scar fibroblasts were treated for 1 h with 50 nM liposome-delivered siRNA against rat gp46 when 80% confluent at passage 1, cultured for an additional 24 h in fresh media, then harvested (control = rat vocal fold scar fibroblasts treated with 50 nM liposome-delivered scramble siRNA).

2014-10-09 | E-GEOD-62204 | biostudies-arrayexpress

Transcription in wounded rat vocal folds and vocal fold fibroblasts

2014-10-09 | GSE62204 | GEO

Sub-millisecond 2D MRI of the vocal fold oscillation using single-point imaging with rapid encoding.

Project description:ObjectiveThe slow spatial encoding of MRI has precluded its application to rapid physiologic motion in the past. The purpose of this study is to introduce a new fast acquisition method and to demonstrate feasibility of encoding rapid two-dimensional motion of human vocal folds with sub-millisecond resolution.MethodIn our previous work, we achieved high temporal resolution by applying a rapidly switched phase encoding gradient along the direction of motion. In this work, we extend phase encoding to the second image direction by using single-point imaging with rapid encoding (SPIRE) to image the two-dimensional vocal fold oscillation in the coronal view. Image data were gated using electroglottography (EGG) and motion corrected. An iterative reconstruction with a total variation (TV) constraint was used and the sequence was also simulated using a motion phantom.ResultsDynamic images of the vocal folds during phonation at pitches of 150 and 165 Hz were acquired in two volunteers and the periodic motion of the vocal folds at a temporal resolution of about 600 µs was shown. The simulations emphasize the necessity of SPIRE for two-dimensional motion encoding.DiscussionSPIRE is a new MRI method to image rapidly oscillating structures and for the first time provides dynamic images of the vocal folds oscillations in the coronal plane.

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