Article

Modifications of Vestibular Fold Shape From Respiration to Phonation in Unilateral Vocal Fold Paralysis

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Abstract

The diversity of vestibular fold (VeF) behavior during phonation, as well as the lack of insight regarding both the anatomy and muscle fiber composition hinder our understanding of their role during phonation. The concave shape of the free margin of VeF appears to be standard, but little is known regarding the variability of this shape. We, therefore, sought to determine the laryngoscopic features related to changes in the free margin of the VeFs during phonation in patients with unilateral vocal fold paralysis. Laryngeal images from 39 patients with unilateral paralysis associated with recurrent laryngeal nerve damage were evaluated with regard to variations in length and shape of the VeFs (concave, straight, or convex) during both respiration and phonation. The VeFs on both the paralyzed and unaffected sides were analyzed during both phonation and respiration resulting in 156 total images. During phonation, all VeFs on the nonparalyzed side were straight or convex, whereas on the paralyzed side, only 20 of the 39 were straight or convex during phonation. During respiration, significant differences in the shape of the nonparalyzed side were observed. During phonation, a nonconcave appearance on the paralyzed side usually correlated with a similar appearance during respiration. VeF length decreased during phonation in 30 nonparalyzed VeFs in contrast to only 13 paralyzed folds. When subjects switched from respiration to phonation, the VeFs were typically nonconcave on the nonparalyzed side. In contrast, on the paralyzed side, nonconcave VeFs were consistent across both tasks. In patients with unilateral vocal fold paralysis, VeF conformation is likely determined from extralaryngeal than intrinsic muscle. These findings have important theoretical considerations for laryngeal treatment.

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... 1,2 Too little is known about the impact of supraglottic laryngeal anatomy and physiology for speaking and singing. [3][4][5] While it is generally assumed the supraglottic structures contribute little to phonation, some reports suggest otherwise. Finnegan and Alipour 6 found that ventricular compression and removal of the ventricular folds appeared to impact true vocal fold vibration in the excised canine larynx. ...
... Stager et al. 13 reported that 68% of patients with vocal nodules and 80% of patients with muscle tension dysphonia demonstrated visible evidence of supraglottic compression. Steffen et al. 3 described differences in ventricular vocal fold shape in patients with unilateral vocal fold paralysis during phonation compared to respiration. Bielamowicz et al. 15 observed more ventricular fold activity in unilateral vocal fold paralysis patients who had normal vocal function measures than in similar patients with abnormal measures suggesting evidence of effective compensation in those who performed better. ...
Article
Supraglottic compression is frequently observed in individuals with dysphonia. It is commonly interpreted as an indication of excessive circumlaryngeal muscular tension and ventricular medialization. The purpose of this study was to describe the aerodynamic and acoustic impact of varying ventricular medialization in a canine model. Subglottal air pressure, glottal airflow, electroglottograph, acoustic signals, and high-speed video images were recorded in seven excised canine larynges mounted in vitro for laryngeal vibratory experimentation. The degree of gap between the ventricular folds was adjusted and measured using sutures and weights. Data were recorded during phonation when the ventricular gap was narrow, neutral, and large. Glottal resistance was estimated by measures of subglottal pressure and glottal flow. Glottal resistance increased systematically as ventricular gap became smaller. Wide ventricular gaps were associated with increases in fundamental frequency and decreases in glottal resistance. Sound pressure level did not appear to be impacted by the adjustments in ventricular gap used in this research. Increases in supraglottic compression and associated reduced ventricular width may be observed in a variety of disorders that affect voice quality. Ventricular compression may interact with true vocal fold posture and vibration resulting in predictable changes in aerodynamic, physiological, acoustic, and perceptual measures of phonation. The data from this report supports the theory that narrow ventricular gaps may be associated with disordered phonation. In vitro and in vivo human data are needed to further test this association.
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Chapter
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