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

Abstract

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.

Figure 1

A, Representative fluoroscopic image of cervical vertebrae (1–7) used as a stationary point of reference for placing 0.5-cm intervals above and below the UES-pharyngeal junction. UES, upper esophageal sphincter; US-MP, US miniprobe. B, Hyperechoic artifacts abruptly appear when the transducer of the US-MP is positioned at the level of the UES-pharyngeal junction during station pull through. This image demonstrates the air-tissue interface where air artifacts are first noted anterior to the flat-shaped muscle.

Figure 2

The specially designed manometry catheter with two perfusion ports, securely fastened (blue bands) to a US-MP. Note that the manometry catheter perfusion ports and US transducer were positioned at the same level to ensure that the same muscle is being simultaneously recorded by the manometry catheter and the US-MP. US-MP, US miniprobe.

Figure 3

The US-MP image of a flat-shaped muscle at the level of the air-tissue interface. The characteristic air artifacts appear as series of semicircular, hyperechoic lines anterior to the muscle. Three sonographic layers were noted (layer 1, hyperechoic; layer 2, hypoechoic; and layer 3, hyperechoic). US-MP, US miniprobe.

Figure 4

The US-MP image of a C-shaped muscle with 3 sonographic layers (layer 1, hyperechoic; layer 2, hypoechoic; and layer 3, hyperechoic). US-MP, US miniprobe.

Figure 5

The US-MP image of an oval-shaped muscle with 4 sonographic layers (layer 1, mixed echoic; layers 2 and 3, hypoechoic; and layer 4, hyperechoic). US-MP, US miniprobe.

Figure 6

The cross-sectional muscle shape for each of the 3 manometrically determined zones in the UES. Zone I (esophago-UES), predominantly oval-shaped; zone II (UES), predominantly C-shaped; and zone III (UES-pharyngeal), predominantly flat-shaped. The distance (cm) from the nares to the tip of the manometry catheter is shown at the top of the representative tracing. UES, upper esophageal sphincter.