Zenker's Diverticulum (ZD) is a sac-like outpouching of the lining of the esophageal wall at the upper esophagus. It is a rare disease typically seen in the middle-aged and older adults. Common symptoms of the disease include difficulties in swallowing (dysphagia), food reflux (regurgitation), unpleasant breath smells (halitosis) and couch, choking and hoarseness etc. (respiratory complications). Pills lodging in the sac and thus unable to take effect is also a common and yet often overlooked problem.

Traditional treatment for ZD included open resection done by head and neck surgeons and direct septum division done by ENT doctors. Septum division done by endoscopists is a new modality of treatment and so far has used the same approach as the ENT doctors-the wall between the sac and the normal esophageal lumen (the septum) is cut down directly so that food will not be held in the sac.

A cutting-edge endoscopic treatment for ZD is now emerging. In this approach, what we call submucosal tunneling endoscopic septum division (STESD), the wall is not cut directly, but inside a tunnel created by lifting the wallpaper (the mucosa lining the esophageal wall). After the muscle septum is completely cut, the mucosa is then sealed by clips, restoring integrity of the esophageal lining.

The advantage of STESD is twofold. First, the esophageal mucosa will be sealed after the operation, so that the chance of extravasation of luminal content with its relevant complications will be smaller. Second, under the protection of the tunnel, the endoscopist will be able to cut the septum completely down to its bottom, ensuring a more satisfactory symptom resolution. In short, our hypothesis is that treating Zenker's diverticulum by the tunneling endoscopic technique should be both safer and more effective than traditional methods.

Patients with symptomatic Zenker's diverticulum are considered for STESD. The diagnosis is based on clinical presentation, barium swallow, EGD and a swallow test to rule out other possible disorders causing cervical dysphagia. A scoring system (Costamagna, GIE, 2016) is used to evaluate severity of the symptoms. Four symptoms are evaluated: 1) dysphagia, 2) regurgitation, 3) daytime respiratory symptoms and 4) nighttime respiratory symptoms. These are scored based on a solid food diet according to the symptom frequency calculated within 2 consecutive weeks: 0-never, 1-1day/ week, 2-2~4days/ week, 3-≥5 days/ week. Under EGD and barium swallow test, configuration of the diverticulum is documented in detail (Shou-Jiang Tang, Laryngoscope, 2008). Quality of life is assessed using the SF-36 form. The pre- and post-STESD symptom score, quality of life score, and diverticulum configuration are compared.

Adverse events are recorded and graded according to the system suggested by the ASGE workshop (Cotton, GIE, 2010).

Inclusion Criteria:

• Diagnosis of Zenker's diverticulum by symptoms, esophagram and/ or EGD
• Symptomatic score≥2 in any of the symptoms or ≥3 in total
• Patients or legal surrogates willing and competent to give informed consent and to comply with follow up visits and tests

Exclusion Criteria:

• Patients with minimal symptoms (score ≤1 in all four symptoms and <3 in total)
• Presence of coagulopathy or pregnancy
• Patients who, in the investigator's opinion, are medically unstable or have a life expectancy of< 2 years, are unable to give informed consent or have poor compliance with follow-up, or whose risks of participating in the study outweigh the benefits