Evaluation of hyoid movement during swallowing using a bend sensor.

Abstract

Movement of the hyoid and laryngeal complex is critical for preventing aspiration, as well as smooth bolus passage through the pharynx. We have developed a non-invasive system for measuring laryngeal movement during swallowing with a bend sensor and have already reported the time coordination between the signal waveform from the sensor and hyoid movement. The aim of this study was to clarify the quantitative association between the output value of the sensor and hyoid movement during swallowing. A small bend sensor was fixed on the skin surface along the midline of the neck of 13 healthy men (mean age, 30.8±4.5years). Laryngeal and hyoid movements during swallowing of 5mL of water were recorded synchronously by the bend sensor and videofluorography. The relationship between the bend sensor output value (LM value) and hyoid position (x- and y-axis displacements) by videofluorography from the onset to the offset of the signal waveform was analysed for all tasks and for each task using Pearson's correlation coefficients. There was a positive correlation between the LM value and hyoid position for all tasks (x-axis displacement: r=.647, y-axis displacement: r=.233). In particular, there was a moderate to high correlation between the LM value and x-axis displacement for each task (.453≤r≤.934). The LM value can be a quantitative parameter of anterior hyoid movement during swallowing that might be associated with bolus flow and upper oesophageal sphincter opening.