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INTRODUCTION: Analysis of medial surface dynamics of the vocal folds (VF) is critical to understanding voice production and treatment of voice disorders. We analyzed VF medial surface vibratory dynamics, evaluating the effects of airflow and nerve stimulation using 3D reconstruction and empirical eigenfunctions (EEF). STUDY DESIGN: In vivo canine hemilarynx phonation. METHODS: An in vivo canine hemilarynx was phonated while graded stimulation of the recurrent and superior laryngeal nerves (RLN and SLN) was performed. For each phonatory condition, vibratory cycles were 3D reconstructed from tattooed landmarks on the VF medial surface at low, medium, and high airflows. Parameters describing medial surface trajectory shape were calculated, and underlying patterns were emphasized using EEFs. Fundamental frequency and smoothed cepstral peak prominence (CPPS) were calculated from acoustic data. RESULTS: Convex-hull area of landmark trajectories increased with increasing flow and decreasing nerve activation level. Trajectory shapes observed included circular, ellipsoid, bent, and figure-eight. They were more circular on the superior and anterior VF, and more elliptical and line-like on the inferior and posterior VF. The EEFs capturing synchronal opening and closing (EEF1) and alternating convergent/divergent (EEF2) glottis shapes were mostly unaffected by flow and nerve stimulation levels. CPPS increased with higher airflow except for low RLN activation and very dominant SLN stimulation. CONCLUSION: We analyzed VF vibration as a function of neuromuscular stimulation and airflow levels. Oscillation patterns such as figure-eight and bent trajectories were linked to high nerve activation and flow. Further studies investigating longer sections of 3D reconstructed oscillations are needed. LEVEL OF EVIDENCE: N/A, Basic Science Laryngoscope, 134:1249-1257, 2024.
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Glotis , Pliegues Vocales , Animales , Perros , Pliegues Vocales/fisiología , Glotis/fisiología , Fonación/fisiología , Nervio Laríngeo Recurrente/fisiología , Nervios Laríngeos/fisiología , VibraciónRESUMEN
INTRODUCTION: Although phonatory glottal posture and airflow pulse shape affect voice quality, studies to date have been limited by visualization of vocal fold (VF) vibration from a superior view. We performed a 3D reconstruction of VF vibratory motion during phonation from a medial view and assessed the glottal volume waveform and resulting acoustics as a function of neuromuscular stimulation. STUDY DESIGN: In vivo canine hemilarynx phonation. METHODS: Across 121 unique combinations of the superior laryngeal nerve (SLN) and recurrent laryngeal nerve (RLN) stimulation, the hemilarynx was excited to the oscillation with airflow. VF medial surface reference points were tracked on high-speed video, mapped into 3D space, and surface shape was restored using cubic spline interpolation. Glottal surface shape, reconstruction-based parameters, and glottal volume waveform were calculated. Fundamental frequency (F0), cepstral peak prominence (CPP), and harmonic amplitude (H1-H2) were measured from high-quality audio samples. RESULTS: The glottis was convergent during opening and divergent during closing. Neuromuscular activation changed phonatory glottal shape and reduced glottal volume. Significant reduction in glottal volume and closing quotient were present with SLN stimulation. RLN stimulation significantly increased F0 and CPP and decreased H1-H2 (constricted glottis), while SLN effects were similar and synergistic with concurrent RLN stimulation. CONCLUSION: 3D reconstruction of in vivo medial surface vibration revealed effects of laryngeal nerve stimulation on glottal vibratory pattern and acoustic correlates of voice quality. SLN activation resulted in significantly quicker glottal closure per cycle, decreased glottal volume, and higher-pitched, less breathy, and less noisy voice. RLN had a similar effect on acoustic measures. LEVEL OF EVIDENCE: NA, Basic Science Laryngoscope, 133:357-365, 2023.
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Glotis , Imagenología Tridimensional , Animales , Perros , Glotis/fisiología , Pliegues Vocales/fisiología , Fonación/fisiología , Calidad de la Voz , VibraciónRESUMEN
OBJECTIVES: Surgical manipulations to treat glottic insufficiency aim to restore the physiologic pre-phonatory glottal shape. However, the physiologic pre-phonatory glottal shape as a function of interactions between all intrinsic laryngeal muscles (ILMs) has not been described. Vocal fold posture and medial surface shape were investigated across concurrent activation and interactions of thyroarytenoid (TA), cricothyroid (CT), and lateral cricoarytenoid/interarytenoid (LCA/IA) muscles. STUDY DESIGN: In vivo canine hemilarynx model. METHODS: The ILMs were stimulated across combinations of four graded levels each from low-to-high activation. A total of 64 distinct medial surface postures (4 TA × 4 CT × 4 LCA/IA levels) were captured using high-speed video. Using a custom 3D interpolation algorithm, the medial surface shape was reconstructed. RESULTS: Combined activation of ILMs yielded a range of unique pre-phonatory postures. Both LCA/IA and TA activation adducted the vocal fold but with greater contribution from TA. The transition from a convergent to a rectangular glottal shape was primarily mediated by TA muscle activation but LCA/IA and TA together resulted in a smooth rectangular glottis compared to TA alone, which caused rectangular glottis with inferomedial bulging. CT activation resulted in a lengthened but slightly abducted glottis. CONCLUSIONS: TA was primarily responsible for the rectangular shape of the adducted glottis with synergistic contribution from the LCA/IA. CT contributed minimally to vocal fold medial shape but elongated the glottis. These findings further refine laryngeal posture goals in surgical correction of glottic insufficiency. LEVEL OF EVIDENCE: NA, Basic science Laryngoscope, 133:1690-1697, 2023.
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Glotis , Músculos Laríngeos , Animales , Perros , Músculos Laríngeos/fisiología , Glotis/fisiología , Fonación/fisiología , Pliegues Vocales/fisiología , Postura , AtrofiaRESUMEN
OBJECTIVES/HYPOTHESIS: Glottal insufficiency is a common clinical problem in otolaryngology and medialization laryngoplasty (ML) procedures remain the primary treatment modality. Although the goal of ML is to restore physiologic glottal posture and achieve optimal phonation, this posture has not been directly measured. In this study, we assessed glottal medial surface contour changes with selective activation of the intrinsic laryngeal muscles (ILMs). STUDY DESIGN: Basic science study using an in vivo canine hemilarynx model. METHODS: In an in vivo canine hemilarynx, India ink was used to mark fleshpoints in a grid-like fashion along the medial surface of the vocal fold and ILMs were activated in a graded manner. A right-angled prism provided two views of the medial surface, which were recorded using a high-speed camera and used to reconstruct the 3D posture deformations of the medial surface. RESULTS: Thyroarytenoid (TA) muscle activation results in initial inferomedial bulging and increased glottal channel thickness and then glottal adduction with a final rectangular glottal channel shape. Lateral cricoarytenoid (LCA) activation closes the posterior glottis but final posture remains slightly convergent. Together, TA + LCA forms a rectangular glottis with an increased glottal vertical thickness. Posterior cricoarytenoid activation results in abduction and a slightly divergent glottis, whereas cricothyroid activation elongates the glottis and reduces the glottal channel vertical thickness. CONCLUSIONS: A quantitative analysis of in vivo canine vocal fold medial surface upon activation of selective ILMs is provided. This may guide our therapeutic efforts during medialization laryngoplasty, as well as computational modeling of laryngeal physiology.
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Músculos Laríngeos/fisiología , Pliegues Vocales/fisiología , Animales , Perros , Técnicas In Vitro , Músculos Laríngeos/diagnóstico por imagen , Pliegues Vocales/diagnóstico por imagenRESUMEN
OBJECTIVE: The aim of this study was to quantify porcine vocal fold medial surface geometry and three-dimensional geometric distortion induced by freezing the larynx, especially in the region of the vocal folds. STUDY DESIGN: The medial surface geometries of five excised porcine larynges were quantified and reported. METHODS: Five porcine larynges were imaged in a micro-CT scanner, frozen, and rescanned. Segmentations and three-dimensional reconstructions were used to quantify and characterize geometric features. Comparisons were made with geometry data previously obtained using canine and human vocal folds as well as geometries of selected synthetic vocal fold models. RESULTS: Freezing induced an overall expansion of approximately 5% in the transverse plane and comparable levels of nonuniform distortion in sagittal and coronal planes. The medial surface of the porcine vocal folds was found to compare reasonably well with other geometries, although the compared geometries exhibited a notable discrepancy with one set of published human female vocal fold geometry. CONCLUSIONS: Porcine vocal folds are qualitatively geometrically similar to data available for canine and human vocal folds, as well as commonly used models. Freezing of tissue in the larynx causes distortion of around 5%. The data can provide direction in estimating uncertainty due to bulk distortion of tissue caused by freezing, as well as quantitative geometric data that can be directly used in developing vocal fold models.