Flexible Endoscopic and Third Space Treatment of Cricopharyngeal Dysfunction and Zenker’s Diverticulum

Purpose of review We describe the evolution and current application of third space endoscopic techniques, with a focus on their role in treating Zenker’s diverticulum (ZD). We discusses the rationale for moving from traditional surgical approaches to minimally invasive flexible endoscopic options. Recent findings Third space endoscopy, initially developed for dysplastic tissue resection, has expanded to also include treatments for motility disorders. Subsequent innovations with third space techniques (tunnelling within the submucosal space), have revolutionized minimally invasive treatment. Flexible diverticulotomy and Zenker-per-oral endoscopy myotomy (Z-POEM), first described in 2016, has emerged as a safe and effective treatment for ZD, with comparable or superior outcomes to surgical and rigid endoscopic techniques. Numerous technical modifications have been used to further simplify and optimize outcomes. We recommend and personally perform cases collaboratively between otolaryngologists, upper gastrointestinal surgeons and gastroenterologists, particularly on the initial learning curve, for optimal patient outcomes. Summary Third space techniques, particularly flexible diverticulectomy and Z-POEM, represent a major shift in the minimally invasive management of Zenker’s diverticulum. While flexible endoscopy is increasingly used and recommended as first-line treatment, the optimal approach should be tailored to individual patient anatomy, proceduralist expertise, and available resources. Continued innovation, multidisciplinary collaboration, and structured training pathways are essential for advancing practice and improving outcomes in this evolving field.