MECHANISM AND TIMING OF NASOPHARYNGEAL CLOSURE DURING SWALLOWING AND BELCHING

The mechanism(s) of nasopharyngeal closure (NPC) and its temporal rela tionship with other biomechanical events during swallowing and belchin g were studied in seven healthy volunteers, aged 26-39 yr, by concurre nt videoendoscopic, videofluoroscopic, and manometric technique. Analy sis of the videoendoscopic recordings showed that deglutitive NPC cons isted of elevation of the soft palate and adduction of the superior ph aryngeal constrictor muscle. Videofluoroscopy identified only the pala tal elevation clearly. During belching, however, only palatal elevatio n occurred. Deglutitive NPC ranged between 0.73 and 0.94 s (0.8 +/- 0. 04 SE), with a tendency to be longer with larger swallowed volumes. On set of NPC was identified earlier endoscopically than as seen fluorosc opically. Complete NPC preceded the arrival of barium bolus into the p harynx, and this pattern was seen for all volumes tested. Manometric o nset of upper esophageal sphincter (UES) relaxation was seen before th e onset of NPC, but the physical opening of the UES as seen fluoroscop ically occurred after complete closure of the nasopharynx. We conclude the following: 1) The mechanism of NPC during swallowing and belching is different. During swallowing, NPC has two tiers of closure, palata l elevation and superior pharyngeal muscle adduction; during belching only palatal elevation occurs. 2) NPC is tightly coordinated with othe r biomechanical events during swallowing and belching.