Hypopharyngeal Diverticulum: Toward a Unified Understanding of Its Etiopathogenesis.

The etiopathogenesis of Zenker's diverticulum (ZD) remains uncertain. Increased hypopharyngeal pressure due to a hypertonic upper esophageal sphincter results in herniation proximal to the sphincter producing a pulsion diverticulum. Gastroesophageal reflux, which is known to induce shortening of the injured esophagus, likely plays a prominent role in ZD formation by pulling the cricopharyngeus muscle (CPM) away from the anchored inferior constrictor muscle. This creates a "weak zone" encouraging herniation. A bilobed diverticulum may originate from continuation of the fibrous midline raphe inferiorly to developmentally include part of the CPM. We report using laser endoscopy to divide the inter-diverticular septum followed by transmucosal cricopharyngeus myotomy. Presentation of a rare, bilobed diverticulum emphasizes the importance of the midline prevertebral raphe in anchoring the pharyngeal constrictor muscles with respect to the CPM. This lends support to the hypothesis that the etiopathogenesis of ZD is multifactorial while guiding us to a unified understanding of ZD.