Digestive Diseases and Sciences, Vol. 49, No. 5 (May 2004), pp. 703–709 ( C  2004) Evaluation of the Upper Esophageal Sphincter (UES) Using Simultaneous High-Resolution Endoluminal Sonography (HRES) and Manometry LARRY S. MILLER, MD, QING DAI, MD, BRETT A. SWEITZER, BA, VINOD THANGADA, MD, JOSEPH K. KIM, BEJE THOMAS, MD, HENRY PARKMAN, MD, and AHMED M. SOLIMAN, MD The aim of this study was to characterize the motion, morphology, and pressure of the upper esophageal sphincter (UES). The UES and its surrounding structures were evaluated in seven normal subjects and four human cadavers, using simultaneous high-resolution endoluminal sonography and manometry. The UES musculature on ultrasound is a C-shaped structure with an angle of 107 ± 19 ◦ . The mean peak resting UES pressure was 74 mm Hg, with a total cross-sectional area (CSA) of 0.87 ± 0.33 cm 2 . During swallowing, the UES moved in an orad direction. Localizing the UES sonographically, the peak UES pressure in the cadavers was 19.7 ± 10.0 mm Hg. The UES has a greater muscular CSA and resting pressure than the upper esophageal body. In the cadaver studies, the UES was imaged in conjunction with a significant increase in pressure, indicating that the pressure is due to passive mechanical conformational changes. KEY WORDS: upper esophageal sphincter; endoluminal ultrasound; manometry; swallowing. The upper esophageal sphincter (UES) helps to regu- late food entry into the esophagus. It is made up of the cricopharyngeus muscle as well as components of sur- rounding structures. In contrast to the rest of the GI sphinc- ter muscles (lower esophageal sphincter [LES], pylorus, and anal sphincter), the UES is less well studied. The unique characteristics of the UES have made precise eval- uation of its anatomy and physiology difficult. Specifi- cally, events at the striated muscle UES during swallow- ing occur quickly relative to events in the rest of the upper gastrointestinal tract. In addition, the anatomy in this area Manuscript received September 17, 2003; accepted March 19, 2004. From Temple University School of Medicine, Philadelphia, Pennsylvania, USA. Address for reprint requests: Larry S. Miller, MD, Department of Gastroenterology, 8th Floor, Parkinson Pavilion Building, Temple Uni- versity Hospital, 3401 North Broad Street, Philadelphia, Pennsylvania 19140, USA; vivi@astro.temple.edu. is complicated and different from that of other areas in the GI tract. Simultaneous use of high-frequency catheter-based ul- trasound transducers and manometry has been used to evaluate the upper gastrointestinal tract lumen, partic- ularly the esophageal wall structures. Miller et al. (1) used simultaneous high-resolution endoluminal sonogra- phy (HRES) and manometry to evaluate esophageal wall motion, muscle thickness, and pressure changes during peristalsis. More recently, McCray, et al. (2) used simulta- neous HRES and manometry to evaluate the high-pressure zones (HPZs) of the distal esophagus, and Wong et al. (3) used the same technology in their assessment of the anal sphincter complex, effectively demonstrating the role of this technology in characterizing luminal HPZs and cor- relating anatomic and physiologic factors. The purpose of the current study was to evaluate UES motion, anatomy, morphology, and pressures at baseline Digestive Diseases and Sciences, Vol. 49, No. 5 (May 2004) 703 0163-2116/04/0500-0703/0 C  2004 Plenum Publishing Corporation