Using Active Shape Modeling Based on MRI to Study Morphologic and Pitch-Related Functional Changes Affecting Vocal Structures and the Airway

Copyright © 2013 The Voice Foundation. Published by Mosby, Inc. All rights reserved.Peer reviewedPostprin

The quantal larynx: The stable regions of laryngeal biomechanics and implications for speech production

Purpose: Recent proposals suggest that (a) the high dimensionality of speech motor control may be reduced via modular neuromuscular organization that takes advantage of intrinsic biomechanical regions of stability and (b) computational modeling provides a means to study whether and how such modularization works. In this study, the focus is on the larynx, a structure that is fundamental to speech production because of its role in phonation and numerous articulatory functions. Method: A 3-dimensional model of the larynx was created using the ArtiSynth platform (http://www.artisynth.org). This model was used to simulate laryngeal articulatory states, including inspiration, glottal fricative, modal prephonation, plain glottal stop, vocal–ventricular stop, and aryepiglotto– epiglottal stop and fricative. Results: Speech-relevant laryngeal biomechanics is rich with “quantal” or highly stable regions within muscle activation space. Conclusions: Quantal laryngeal biomechanics complement a modular view of speech control and have implications for the articulatory–biomechanical grounding of numerous phonetic and phonological phenomen

Biomechanical Models of Human Upper and Tracheal Airway Functionality

The respiratory tract, in other words, the airway, is the primary airflow path for several physiological activities such as coughing, breathing, and sneezing. Diseases can impact airway functionality through various means including cancer of the head and neck, Neurological disorders such as Parkinson\u27s disease, and sleep disorders and all of which are considered in this study. In this dissertation, numerical modeling techniques were used to simulate three distinct airway diseases: a weak cough leading to aspiration, upper airway patency in obstructive sleep apnea, and tongue cancer in swallow disorders. The work described in this dissertation, therefore, divided into three biomechanical models, of which fluid and particulate dynamics model of cough is the first. Cough is an airway protective mechanism, which results from a coordinated series of respiratory, laryngeal, and pharyngeal muscle activity. Patients with diminished upper airway protection often exhibit cough impairment resulting in aspiration pneumonia. Computational Fluid Dynamics (CFD) technique was used to simulate airflow and penetrant behavior in the airway geometry reconstructed from Computed Tomography (CT) images acquired from participants. The second study describes Obstructive Sleep Apnea (OSA) and the effects of dilator muscular activation on the human retro-lingual airway in OSA. Computations were performed for the inspiration stage of the breathing cycle, utilizing a fluid-structure interaction (FSI) method to couple structural deformation with airflow dynamics. The spatiotemporal deformation of the structures surrounding the airway wall was predicted and found to be in general agreement with observed changes in luminal opening and the distribution of airflow from upright to supine posture. The third study describes the effects of cancer of the tongue base on tongue motion during swallow. A three-dimensional biomechanical model was developed and used to calculate the spatiotemporal deformation of the tongue under a sequence of movements which simulate the oral stage of swallow

Forces acting on the maxillary incisor teeth during laryngoscopy using the Macintosh laryngoscope

We determined the forces on the maxillary incisors during routine laryngoscopy in 65 adult patients. The forces were measured by a strain gauge based sensor positioned between the handle and the blade of the laryngoscope. The mean maximal force acting on the maxillary incisors was 49 N. In patients without maxillary incisors, the force acting on the gums was significantly lower at 21N (p < 0.001). These results suggest that, despite traditional advice to the contrary, a levering movement of the laryngoscope, using the maxillary incisors (or gums) as a fulcrum, is common practice. Biomechanical analysis revealed that, although levering is not the preferred movement, it is an efficient way of bringing the glottis into view. These results may have implications for future laryngoscope design

Breathing Re-Education and Phenotypes of Sleep Apnea: a Review

Four phenotypes of obstructive sleep apnea hypopnea syndrome (OSAHS) have been identified. Only one of these is anatomical. As such, anatomically based treatments for OSAHS may not fully resolve the condition. Equally, compliance and uptake of gold-standard treatments is inadequate. This has led to interest in novel therapies that provide the basis for personalized treatment protocols. This review examines each of the four phenotypes of OSAHS and explores how these could be targeted using breathing re-education from three dimensions of functional breathing: biochemical, biomechanical and resonant frequency. Breathing re-education and myofunctional therapy may be helpful for patients across all four phenotypes of OSAHS. More research is urgently needed to investigate the therapeutic benefits of restoring nasal breathing and functional breathing patterns across all three dimensions in order to provide a treatment approach that is tailored to the individual patient

THE EFFECTS OF THE EFFORTFUL SWALLOW MANEUVER ON HYOLARYNGEAL MOVEMENT AND TONGUE-TO-PALATE PRESSURE

Purpose: The purpose of this study was to investigate the effects of the effortful swallow maneuver under two different instructions on tongue-to-palate pressure and hyolaryngeal displacement in healthy adults. Studying typical kinematic parameters and pressure generation in healthy individuals is critical for differentiating normal from pathological patterns and for determining swallowing parameters that can be targeted to optimize and individualize treatment plans for people with swallowing disorders. The primary objectives in this study were: (1) to determine the physiological effects of two different types of effortful swallows on anterior and posterior tongue pressure generation, hyoid displacement, and hyoid-larynx approximation in healthy adults, (2) to determine age-related differences in tongue-to-palate pressure and hyolaryngeal displacement in healthy adults, and (3) to determine the association between perceived effort used to swallow and tongue pressure within swallowing conditions.Method: Forty healthy adults (20 younger, 20 older) participated in this study. All participants were in general good health, were screened for normal oral structures, function, and swallowing skills, had normal tongue strength, were eating a normal diet, and had normal auditory comprehension skills. Experimental procedures included simultaneous data acquisition of tongue pressure, submental muscle activity, and hyolaryngeal movement during normal saliva swallows and effortful saliva swallows under two different instructions (tongue emphasis and neck squeezing). Measures of tongue pressure were obtained using the Iowa Oral Performance Instrument. Submental muscle activity during swallows was assessed using surface electromyography. Hyoid excursion and hyoid-larynx approximation were obtained during ultrasonography. All outcome measures were scaled to account for differences between participants and they reflected activity during swallowing. Moreover, participants rated their perceived effort used to swallow with a visual analog scale. Results: Significant tongue pressure differences were observed between swallowing condition and tongue region. The effortful swallows performed with tongue emphasis (EFSst) and pharyngeal squeezing (EFSsp) produced greater tongue-to-plate pressures than normal swallows (NSs). Additionally, posterior tongue pressures were greater than pressures generated in the anterior tongue region during NSs and EFSst. Hyolaryngeal measures were also greater during EFSst and EFSsp than NSs. Significant differences were found between the two types of effortful swallows in tongue pressure and hyoid displacement measurements. Overall, EFSst produced greater changes in these physiological measures than EFSsp. Significant age-related differences were only found in hyoid-larynx approximation during the EFSst. Moderate correlations were identified between tongue pressure and hyoid displacement during NSs and EFSst and between tongue pressure and hyoid-larynx approximation during NSs and EFSst. Results also showed that participants perceived greater effort used to swallow during EFSst and EFSsp than NSs. Finally, there was a significant, moderate correlation between perceived swallowing effort and objectively measured tongue-to-palate pressure during NSs and EFSst. Conclusions: The effortful swallow maneuver increases tongue-to-palate pressure and hyolaryngeal excursion in healthy adults across the age span. Additionally, different instructions for the effortful swallow affect those physiological measures. These findings have the potential to guide treatment decisions when recommending and training the effortful swallow maneuver. It may be helpful for clinicians to individualize and determine the optimal effortful swallow instructions for each patient based on their physiological swallowing impairments