Functional Changes of the Upper Esophageal Sphincter in Gastroesophageal Reflux.

The upper esophageal sphincter (UES) is a muscular structure located at the transition from the pharynx to the esophagus, with the cricopharyngeal muscle as the most important component. During gastroesophageal reflux, the pressure in the UES elevates, which is apparently a protective mechanism to prevent esophagopharyngeal reflux and airway aspiration. In gastroesophageal reflux disease (GERD), there may be functional changes in the UES.  The objective of the present review was to determine UES functional changes in GERD.  In healthy individuals, gastroesophageal reflux causes an increase in the UES pressure. This response of the sphincter is at least partially impaired in patients with GERD. In the disease, the UES has a reduced length and decreased resting pressure. However, other publications found that in chronic gastroesophageal reflux the basal sphincter pressure increase, differences which may be consequent to the measurement method or to disease severity. The UES opening during swallowing has a smaller diameter, and the bolus transit time through the sphincter is longer.  The UES of patients with GERD does not open as expected and the bolus flow through the sphincter is longer. This behavior may be associated with dysphagia, a frequent complaint in patients with GERD.