Surface electromyography in preoperative evaluation and postoperative monitoring of Zenker's diverticulum.

Patients with Zenker's diverticulum (ZD) underwent surface electromyography (sEMG) evaluation to determine sEMG patterns specific for ZD. Group 1 comprised patients with proven long-standing ZD that refused surgical treatment (n = 11, age mean = 55.7 years). Group 2 comprised surgically operated on patients with ZD (n = 6, age mean = 61 years). The timing, amplitude, and graphic patterns of activity of the masseter, submental, and laryngeal strap muscles were examined during voluntary single water swallows ("normal"), single swallows of excessive amounts of water (20 ml, "stress test"), and continuous drinking of 100 cc of water. The muscle activity in pharyngeal and initial esophageal stages of swallowing was measured, and graphic records were evaluated in relation to timing and voltage. The data were compared with the previously established normative database. The main sEMG patterns of ZD are (1) duration of swallowing and drinking is longer than normal (p < 0.05), (2) electric amplitude of laryngeal strap muscles during swallowing activity is higher than normal (p < 0.05), and (3) regurgitation peaks immediately after swallow followed by secondary swallow of the regurgitated portion of a bolus as seen at the sEMG records are specific graphic patterns for the ZD. Zenker's diverticulum has its own specific sEMG patterns. Surface EMG, being an important screening method for patients with dysphagia, is a valuable additional diagnostic tool for ZD. Because it is noninvasive and nonradiographic, it can be used for monitoring of long-standing cases of the disease as well as monitoring of postsurgical recovery.