Differences in upper esophageal sphincter function and clinical characteristics among the three subtypes of Japanese patients with esophageal achalasia.

A negative correlation was confirmed between resting upper esophageal sphincter pressure and age in all subtypes of esophageal achalasia. Type III patients were older at diagnosis, type II patients showed higher upper esophageal sphincter pressure, and type I patients showed a lower upper esophageal sphincter pressure at the early life stage.