The Application of Ultrasound Evaluation of Swallowing to the Analysis of Hyoid Kinematics in Healthy Swallows

Abstract

Purpose: Using ultrasound as an adjunct tool for swallowing assessment has gained significant momentum in recent years, with research gaps in areas such as speech and language therapist–driven protocol and measurement methods. This study outlines the recording protocol of Ultrasound Evaluation of Swallow-ing (USES). Additionally, a set of multidimensional measurements capturing the hyoid kinematics in typical swallows was compared with previous studies to evaluate the current protocol and to develop an ultrasound database of healthy swallows to further the clinical implementation of USES. Method: Swallowing data were acquired from 41 healthy participants. Both dis-crete swallows (5-and 10-ml) and continuous swallows (100-ml) were analyzed. Automatic tracking of the hyoid and mandible positions using a deep neural net was applied. Six swallowing events of interest were identified for each swallow (beginning hyoid position, maximal hyoid position, hyoid advancement, hyoid retraction, peak forward velocity, and peak backward velocity), and a series of hyoid parameters characterizing the amplitude, velocity, and timing of the movement were calculated and compared across different types of swallows. Results: Results showed significant differences between continuous and dis-crete swallows. Continuous swallows were characterized by shorter maximal hyoid displacement, a shorter duration between the start of the swallow and the maximal displacement, a shorter total swallow duration, and lower peak velocity in both forward and backward hyoid movement. No significant difference was observed between the 5-and 10-ml swallows in hyoid movement amplitude, velocity, or duration. Conclusions: The quantification of hyoid kinematics in swallowing through the current USES recording protocol, combined with the semi-automatic extraction of hyoid function by applying a deep neural net and feature-finding algorithms, provides initial evidence to support its clinical utility in swallowing assessment. Further studies, including those of different clinical populations, to evaluate the sensitivity of the hyoid metrics in detecting changes to swallowing would sup-port the clinical translation.