Anatomic-manometric correlation of the upper esophageal sphincter: a concurrent US and manometry study

Background

The pharyngoesophageal segment commonly referred to as the upper esophageal sphincter (UES) generates a high-pressure zone (HPZ) between the pharynx and the esophagus. However, the exact anatomical components of the UES-HPZ remain incompletely determined.

Objective

To systematically define the US signature of various components of the pharyngoesophageal junction and to determine how these structures contribute to the development of the UES-HPZ.

Design

Prospective, experimental study.

Setting

Tertiary Academic Medical Center.

Patients

This study involved 18 healthy volunteers.

Intervention

We studied 5 participants by using a high-frequency US miniprobe (US-MP) and concurrent fluoroscopy and another 13 participants by using the US-MP and concurrent manometry.

Main Outcome Measurements

Relative contribution of various muscles in the UES-HPZ.

Results

Manometrically, the UES-HPZ had a median length of 4.0 cm (range 3.0-4.5 cm). A C-shaped muscle, believed to represent the cricopharyngeus muscle, was observed for a median length of 3.5 cm (range 2.0-4.0 cm). The oval configuration representing the esophageal contribution to the UES was seen in 10 of 13 participants (77%) at the distal HPZ (esophagus to UES transition zone). The flat configuration of the inferior constrictor muscle was noted in 7 of 13 participants (54%) at the proximal HPZ (UES to pharynx transition zone). There were 4 to 5 wall layers versus 3 layers in the distal and proximal HPZ, respectively. The mean (± SD) muscle thickness was relatively constant along the length of the UES-HPZ.

Limitations

Air artifacts in the UES-HPZ.

Conclusion

The configuration and layers of the UES-HPZ vary along its length. The upper esophagus is a significant contributor to the distal UES-HPZ.

Abbreviations: HPZ, high-pressure zone, MMMT, mean maximal muscle thickness, UES, upper esophageal sphincter, US-MP, high-frequency US miniprobe