Pharyngeal swallowing mechanics associated with upper esophageal sphincter pressure wave

Abstract

BACKGROUND: Opening of the upper esophageal sphincter (UES) is a critical element of swallowing. Understanding the functional pharyngeal anatomy during UES opening would be clinically useful for dysphagia evaluation and treatment. METHODS: Simultaneous high-resolution pharyngeal manometry and videofluoroscopy (VFS) videos for 18 nondysphagic subjects were evaluated. UES pressure readings were segmented into six pressure phases, including a poorly understood pre-relaxation contraction. Anatomic landmarks were tracked in VFS imaging and evaluated morphometrically to determine the movement of key swallowing structures within each UES pressure phase. RESULTS: There were significant differences in pharyngeal mechanics by UES pressure stage (range of D-values = 1.7-2.2, P < .0001). The soft palate maximally elevates during the pre-relaxation contraction of the UES. Early during UES relaxation, the hyolaryngeal complex and pharyngeal structures maximally elevate and pharyngeal structures constrict around the bolus. CONCLUSION: The mechanics underlying the UES pressure wave suggest generation of a sealed pharyngeal cavity, possibly integral to pharyngeal pressure generation and bolus propulsion.