Ultrasound analysis of the upper esophageal sphincter during swallowing in the healthy subject.

Objectives: The purpose of this study was to develop a methodology and standard settings for ultrasound study of the upper esophageal sphincter (UES) during swallowing.
Material and Methods: This was a prospective study of 25 healthy volunteers (15 women and 10 men) aged 20 to 56 years. Neck ultrasonography was performed as each volunteer swallowed 10 mL of water three times. The parameters studied were: diameter of the closed UES; diameter of the open UES; anterior and lateral displacement (measured in cm) of the UES as the water bolus flowed through it; duration of UES opening; and average duration of UES displacement (measured in ms). Student's t tests for paired and unpaired samples were applied for the statistical analysis.
Results: The mean diameter of the closed UES was 0.78 ± 0.13 cm, while the mean duration of opening was 415 ± 57.66 ms and the mean duration of displacement was 937 ± 120.98 ms. Maximum anterior and lateral displacement of the UES was 0.42 ± 0.12 cm and 0.35 ± 0.18 cm, respectively. There was a significant difference between men and women for lateral displacement of the UES (P=0.04).
Conclusion: This study established standards for ultrasound study of the UES during swallowing, using a non-invasive readily accessible method that may be useful for assessing swallowing disorders involving the UES (Zenker's diverticulum, fibrosis, stricture).
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