The use of intraluminal manometry to assess upper esophageal sphincter function.

The UES is a striated muscular structure that exhibits substantial variation in tone in response to a wide variety of stimuli as well as during deglutition. It is an asymmetric structure subject to substantial axial movement. Hence the findings on UES manometry are highly dependent upon the manometry equipment used, positioning of this equipment in relation to the UES, and external stimuli. There is considerable intrasubject and intersubject variation in some parameters from UES pressure recordings. These factors must be taken into accout in the clinical use of UES manometry.