An analysis of the relationship between hyoid bone movement and ultrasound signal during swallowing: A proof of concept study

Swallowing monitoring and assessment system (SMAS) using an ultrasonic Doppler sensor array was developed to overcome the limitations of existing dysphagia evaluation methods such as videofluoroscopic swallowing study (VFSS) and fiberoptic endoscopic evaluation of swallowing (FEES). This study aimed to identify the relationship between swallowing-related hyoid bone movements measured through VFSS imaging and ultrasound signals collected using SMAS. SMAS signals and VFSS images were collected when 10 healthy participants (6 males and 4 females) performed swallowing movements under a combination of 2 viscosity (Vc) conditions (thin and thick) and 2 vol (Vl) conditions (3 ml and 9 ml). The VFSS images and ultrasound signals were divided into 10 -time intervals; for each time interval the movement speeds of the hyoid bone on the anterior-posterior (AP) and superior-inferior (SI) axes and the average amplitude were analyzed. A 3 -phase swallowing motion profile (posterior-superior (P-S) ascending, anterior-superior (A -S) ascending, and posterior-inferior (P -I) descending) of the hyoid bone was identified. While the composite distance (2.55 +/- 0.13 cm) and time (0.72 +/- 0.03 sec) of hyoid bone movement were the longest in the P -I descending phase, the composite speed of hyoid bone movement (7.25 +/- 0.51 cm/s) was the fastest in the A -S ascending phase. The correlation between hyoid bone movement speed and average SMAS amplitude was highest in the AP axis (r = 0.68 +/- 0.03). Further research is needed to examine if the presence of dysphagia and their severity level can be identified using SMAS.