Inhibition of progressing primary esophageal peristalsis by pharyngeal water stimulation in humans

Background and Aims: Sensory impulses initiated from the pharynx exert differing effects on the deglutitive apparatus. They have an inhibitory effect on the lower esophageal sphincter but an excitatory effect on the upper esophageal sphincter. The aim of this study was to systematically investigate the effect of pharyngeal sensory impulses evoked by water stimulation on the progressing esophageal peristalsis. Methods: Sixteen healthy young volunteers were studied in the supine position. The presence of normal peristalsis was verified. Esophageal peristalsis was recorded 3, 6, 9, 12, 15, and 18 cm above the lower esophageal sphincter. Pharyngeal stimulation was performed by injecting a predetermined threshold volume into the pharynx 2 cm above the upper esophageal sphincter, directed posteriorly. The injections were timed to coincide with the arrival of the peristaltic wave induced by dry swallows at respective recording sites. Results: Injection of the threshold volume (0.5 ± 0.1 mL) stopped the progression of peristalsis at both the striated and smooth muscle esophagus. Topical pharyngeal anesthesia blocked this inhibitory effect (P < 0.01). Conclusions: Sensory impulses initiated from the pharynx evoked by water injection inhibit the progression of primary esophageal peristalsis. Although the clinical significance of these findings is not determined, they may explain the mechanism of some of the failed esophageal peristalsis.