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Date of Graduation
Doctor of Philosophy (PhD)
Department of Communication Sciences and Disorders
Hyoid and laryngeal movements contribute to laryngeal vestibule closure and upper esophageal sphincter (UES) opening for safe swallowing. However, the extent of movement required for achieving these goals, and the interaction between hyoid and laryngeal movements during swallowing are unknown. Despite impairment in vestibule closure and UES opening, patients with dysphagia may exhibit reduced, increased or similar hyolaryngeal displacements as healthy individuals. This limits the delineation between normal and disordered swallowing. We investigated whether anatomical differences in hyolaryngeal positions and the extent of laryngeal vestibule opening at rest would better predict hyolaryngeal displacements and the extent of vestibule closure during swallowing than neck length. We then examined if hyolaryngeal maximal displacements that corrected for individual anatomical differences would show greater contrast between the swallows of patients and healthy individuals than uncorrected measures. We also investigated if the relationship between hyoid and laryngeal elevation, as well as measures of laryngeal elevation peak velocity, timing and movement patterning would differ between patients and controls swallowing more than corresponding measures of hyoid elevation. Videofluoroscopic examinations of swallowing were performed in healthy adults and patients with dysphagia. Using frame-by-frame motion analysis, measures of forward and upward hyolaryngeal displacements and velocities, and vestibule area were made during swallowing. In healthy volunteers, the extent of laryngeal vestibule opening at rest predicted the extent to which laryngeal elevation exceeded hyoid elevation for closing the space between the hyoid and larynx during swallowing. Spatially normalized measures of hyoid and laryngeal elevation magnitudes showed greater differences between normal and abnormal swallowing than raw measures. Patients with dysphagia had insufficient laryngeal elevation relative to hyoid elevation to achieve vestibule closure during swallowing. In conclusion, healthy individuals may adapt hyolaryngeal movement magnitudes according to changes in the movement targets required for vestibule closure to ensure safe swallowing. Insufficient laryngeal elevation relative to hyoid elevation may be detrimental to airway protection for swallowing in dysphagia.
Wong, Seng Mun, "Hyolaryngeal kinematics and swallow patterning in normal and disordered swallowing" (2015). Dissertations, 2014-2019. 31.