Effect of pharyngeal stimulation on the motor function of the esophagus and its sphincters

Objectives/Hypothesis: Sensory impulses from the pharynx induce contraction of the upper esophageal sphincter (UES), relaxation of the lower esophageal sphincter (LES), and inhibition of peristalsis. To determine 1) the magnitude of UES contractile response to threshold volume of fluid that induces LES relaxation and 2) the effect of rapid pharyngeal air stimulation on LES resting pressure and its concurrent influence on the UES and progression of esophageal peristalsis. Methods: Eleven healthy volunteers (age, 31 +/- 2 y) were studied by concurrent UES, esophageal-body, and LES manometry. Results: At a threshold volume of 0.3 +/- 0.05 mt, injections of water into the pharynx directed posteriorly, resulted in complete LES relaxation, Duration of these relaxations averaged 19 +/- 1 seconds. In 10 of 11 subjects, these relaxations were accompanied by a simultaneous increase in UES resting tone that averaged 142% +/- 27% above preinjection values. Pharyngeal stimulation by rapid air injection resulted in complete LES relaxation in 8 of the II subjects (threshold volume, 14 +/- 6 mt). Five of 8 developed a concurrent mild increase in resting UES pressure (17% +/- 6% above preinjection values) (P <.05), Pharyngeal water injection inhibited the progression of the peristaltic pressure wave at all tested sites and in all subjects, but pharyngeal air injection in only 2 of the 11 studied subjects. Conclusions: The inhibitory effect of pharyngeal water injection on LES resting pressure is accompanied by a substantial contractile effect on the UES, Although stimulation of the pharynx by rapid air injection may induce LES re laxation, its inhibitory effect on esophageal peristalsis and stimulatory effect on UES pressure are negligible compared with that of water injection.