Computational analysis of swallowing mechanics underlying impaired epiglottic inversion

Abstract

Objective Determine swallowing mechanics associated with the first and second epiglottic movements, that is, movement to horizontal and full inversion respectively, in order to provide a clinical interpretation of impaired epiglottic function. Study Design Retrospective cohort study. Methods A heterogeneous cohort of patients with swallowing difficulties was identified (n=92). Two speech-language pathologists reviewed 5ml thin and 5ml pudding videofluoroscopic swallow studies per subject, and assigned epiglottic component scores of 0=complete inversion, 1=partial inversion, and 2=no inversion forming three groups of videos for comparison. Coordinates mapping minimum and maximum excursion of the hyoid, pharynx, larynx, and tongue base during pharyngeal swallowing were recorded using ImageJ software. A canonical variate analysis with post-hoc discriminant function analysis of coordinates was performed using MorphoJ software to evaluate mechanical differences between groups. Eigenvectors characterizing swallowing mechanics underlying impaired epiglottic movements were visualized. Results Nineteen of 184 video-swallows were rejected for poor quality (n=165). A Goodman-Kruskal index of predictive association showed no correlation between epiglottic component scores and etiologies of dysphagia (λ=.04). A two-way analysis of variance by epiglottic component scores showed no significant interaction effects between sex and age (f=1.4, p=.25). Discriminant function analysis demonstrated statistically significant mechanical differences between epiglottic component scores: 1&2, representing the first epiglottic movement (Mahalanobis distance=1.13, p=.0007); and, 0&1, representing the second epiglottic movement (Mahalanobis distance=0.83, p=.003). Eigenvectors indicate that laryngeal elevation and tongue base retraction underlie both epiglottic movements. Conclusion Results suggest that reduced tongue base retraction and laryngeal elevation underlie impaired first and second epiglottic movements. The styloglossus, hyoglossus and long pharyngeal muscles are implicated as targets for rehabilitation in dysphagic patients with impaired epiglottic inversion.

Validation of the Normalized Laryngeal Constriction Ratio in Normal and Disordered Swallowing

“…Further, previous studies have shown that, although there is likely a correlation between hyoid movement and epiglottic inversion, hyoid excursion is not necessary for epiglottic inversion. Impaired epiglottic inversion is primarily caused by reduced elevation and reduced tongue base retraction but not by reductions in hyoid movement . It is thought that the pharyngeal longitudinal muscles play a role in inversion of the epiglottis as well as closure of the laryngeal aperture when functioning with the muscular components of the aryepiglottic folds .…”

Pharyngeal swallowing mechanics associated with upper esophageal sphincter pressure wave

“…15 Relevant to this study, CASM can analyze the movement of pharyngeal muscle groups and structures that may cause measurable changes in the HRPM UES pressure profile. 15 Relevant to this study, CASM can analyze the movement of pharyngeal muscle groups and structures that may cause measurable changes in the HRPM UES pressure profile.…”

Pharyngeal Swallowing Mechanics Secondary to Hemispheric Stroke

“…These landmarks can be reliably obtained from imaging data including hyoid movement, laryngeal elevation, tongue base retraction, pharyngeal shortening, and head and neck posture (Figure 1) [37, 38]. Configurations of coordinates represent the interaction of multiple muscle groups underlying pharyngeal swallowing mechanics as these landmarks are displaced.…”