Flexible endoscopic treatment for Zenker's diverticulum: from the lumen to the third space

Zenker's diverticulum (ZD) is a rare outpouching of the esophageal mucosa herniating posteriorly through Killian's triangle. Treatments of ZD aim to dissect the cricopharyngeal muscle to remove the underlying dysfunctional condition. In the last decade, a septotomy performed utilizing a flexible endoscope has been reported as a safe and effective alternative to both open surgery and rigid endoscopic diverticulotomy. More recently, Li et al described a novel endoscopic technique to treat ZD, named "submucosal tunneling endoscopic septum division", inspired by the peroral endoscopic myotomy (POEM) procedure developed for achalasia. Subsequently, the term Z-POEM was introduced and has become the most frequently used acronym to define the tunneling technique for ZD. This article describes the flexible therapeutic endoscopic strategies for treating ZD, including the novel third space approach, which seems to show promising potential in terms of clinical efficacy and safety.