Quantitative assessment of hyoid bone displacement from video images during swallowing.

Given the relationship between hyoid displacement and aspiration, a simple, accurate, clinically useful method for identification of reduced hyoid displacement is needed. The purpose of this investigation was to validate a quantitative method for clinically assessing hyoid bone movement during swallowing. Videofluoroscopic evaluations of 20 male subjects--10 who had been subjectively assessed as demonstrating normal hyoid displacement during swallowing, and 10 who had been subjectively assessed as demonstrating reduced displacement during swallowing--were analyzed. A video measuring gauge was used, and a software spreadsheet was developed to perform trigonometric calculations for determination of anterior/superior hyoid trajectories. Statistically significant differences were found between groups in both the anterior and superior directions of hyoid movement. No significant differences were found between liquid and paste swallows within groups. This method is simple in that it is necessary to identify only three to five points on two video images. Those values are then input onto a preprogrammed spreadsheet that automatically performs the necessary calculations. Although the present investigation focused on the movements of the hyoid bone during swallowing, this method of tracking displacement can be used for virtually any task or structure whose movements can be captured on videotape.