The upper esophageal sphincter during normal deglutition. A simultaneous cineradiographic and manometric investigation.

The upper esophageal sphincter was studied during deglutition in 7 healthy subjects using simultaneous cineradiography and manometry. The pressure measuring device consisted of 3 sensors distally placed, and separated by 10 mm. They recorded pressure obliquely to the right at an angle of 15 to 45 degrees anteriorly. During the swallowing sequence a pressure sensor initially placed in the high pressure zone of the sphincter easily slid out of position due to asynchronous movements of the sphincter and the pressure measuring device. These movements can result in erroneous interpretation of pressure recordings. Continuous radiologic monitoring during the entire swallowing sequence thus seems to be mandatory. Immediately before the bolus entered the upper esophageal sphincter, the sphincter relaxed and low or even negative pressures were registered. When the bolus had passed onwards the sphincter contracted gradually, to resume its pre-swallow pressure.