Pathophysiologic basis for operation on Zenker's diverticulum.

An increased resistance to bolus flow through the upper esophageal sphincter has in the past been considered the main cause of increased pharyngeal contraction and the subsequent development of Zenker's diverticulum (ZD). Our study was designed to elucidate the pathophysiologic characteristics of the swallowing mechanism and its possible role in the development of ZD. Fourteen patients with radiologically proved ZD and a matched control group of healthy volunteers with no gastrointestinal symptoms were investigated with esophageal manometry using the station pull-through technique. Although the mean amplitude of pharyngeal contraction was higher in the ZD group, there was no difference in the duration of contraction. The resting tone of the upper esophageal sphincter zone in patients with ZD was found to be lower than normal, but the closing pressure was higher and its duration longer. Though present in 2 patients, pharyngosphincteric incoordination was not the main feature in the ZD group. Sphincteroesophageal incoordination was noted in 9 patients, however. The mean amplitude of the upper esophageal contraction was higher and the duration longer in the ZD group. There was no upper esophageal peristalsis in 3 patients. An operation for the repair of ZD should therefore be undertaken only after careful interpretation of the manometric features of each patient.