The relationship between bolus volume and hyoid displacement in dysphagia patients with nasopharyngeal carcinoma after radiation therapy

Abstract

Objective To evaluate the relationship between bolus volume and hyoid displacement in dysphagia patients with nasopharyngeal carcinoma after radiation therapy. Methods Twenty-three nasopharyngeal carcinoma patients with dysphagia were recruited and their swallowing of 3, 5, 10 and 20ml of liquid food was studied fluoroscopically. The vertical and horizontal displacement of the hyoid as well as its time in motion were measured, and the relationship between the bolus volume, hyoid displacement and time in motion time was evaluated. Results The largest vertical displacement of the hyoid (1.01±0.65cm) was observed when swallowing a 10ml bolus. The hyoid showed the smallest average horizontal displacement (0.39±0.34cm), when swallowing a 3ml bolus. The average motion time of the hyoid was (2.11±0.65) seconds. It was shorter when swallowing a 10 or 20ml bolus than when dealing with a smaller one. Hyoid motion time was negatively correlated with the horizontal displacement of the hyoid bone, and the volume of a swallow was negatively correlated with the hyoid motion time but positively correlated with the penetration-aspiration scale score. Conclusion Bolus volume affects hyoid displacement and hyoid motion time in nasopharyngeal carcinoma patients with dysphagia after radiation therapy. For patients with a penetration-aspiration scale score of 5 or less, the optimum bolus volume is 5 to 10ml. Key words: Bolus volume; Hyoid displacement; Nasopharyngeal carcinoma; Radiation therapy; Dysphagia