Influence of aging on movement of the hyoid bone and epiglottis during normal swallowing: a motion analysis.

BACKGROUND: The age-related effects on various aspects of swallowing have been reported in studies on the temporal relationship between hyolaryngeal movement and bolus location, as well as the extent of hyolaryngeal movement. However, few studies have described the temporal and spatial relationships concurrently. OBJECTIVE: The main purpose of this study was to define the kinematics of the hyoid bone and epiglottis, during swallowing, on the temporal and spatial relationships concurrently in healthy subjects, and to investigate the influence of aging on hyolaryngeal movement. METHODS: We performed a two-dimensional motion analysis of the hyoid bone and epiglottis using videofluoroscopy images in 69 normal subjects. The trajectories of the hyolaryngeal movement and passage of a bolus were superimposed to form one plot. Temporal measurements included initiation and duration of the hyoid bone and epiglottis movement compared to their movement with the bolus. The spatial measurements included vertical and horizontal excursion of the hyoid bone, and the rotational angle of the epiglottis. RESULTS: The duration of supraglottis closure, and the maximal vertical excursion of the hyoid bone were increased in older subjects, more than 65 years of age, compared to younger subjects (p<0.05). Other temporal and spatial measurements were not statistically significant in the comparisons among the age groups. The vertical distance of the cervical vertebra was related to vertical excursion of the hyoid bone (p=0.002), and the horizontal distance from the chin to the cervical vertebra was related to the horizontal excursion of the hyoid bone (p=0.003). CONCLUSION: This paper describes a method for assessing temporal and spatial relationships of hyolaryngeal movement, and the passage of a bolus during swallowing. The two-dimensional kinematic swallowing motion analyses that were developed provided useful data that changed with age.