Diverticula of Esophagus
Diverticula may form at any point along the length of the esophagus. The pathogenesis of the diverticula is usually either pulsion (due to high intrinsic esophageal pressure secondary to a motility disorder) or traction secondary to a process extrinsic to but neighboring the esophagus that tethers to and pulls the esophageal wall away from the lumen.
In the proximal esophagus, a pulsion Zenker diverticulum may form. This outpouching occurs in a mechanistically weak area of the pharynx located posteriorly between the inferior pharyngeal constrictor and the cricopharyngeus muscles (triangle of Killian). The source of pulsion forces is felt to be contraction of the pharynx against a fibrotic, poorly compliant cricopharyngeus. Treatment is myotomy of the cricopharyngeus to prevent reformation with diverticulectomy, diverticulopexy, or division, depending on the size of the diverticulum. In the midesophagus, traction diverticula are more common. These typically occur from external tethering forces, such as mediastinal adenopathy involved with cancer or with granulomatous infection, such as tuberculosis or histoplasmosis. The openings of the outpouchings tend to be broader, without acute entry into the esophagus when compared with the pulsion type. Nonspecific diverticula, possibly due to pulsion, may also form in the midesophagus, often incidentally and sometimes causing symptoms. The precise etiology is unclear.
A distal esophageal epiphrenic diverticulum is typically caused by pulsion and forms proximal to the gastroesophageal junction. It generally results from a hypertensive lower esophageal sphincter with or without changes of achalasia. Similar to treatment of a Zenker diverticulum, a myotomy of the highpressure zone must be performed, in addition to diverticulectomy for large sacs.