Esophageal Diverticula

Background

A diverticulum is a sac or pouch arising from a tubular organ, such as the esophagus. This article focuses on diverticula of the esophagus. As is common practice, Zenker diverticulum, a type of diverticulum that arises from the posterior hypopharynx, is also discussed in this article.

Pathophysiology

Besides anatomical location, several other ways to classify diverticula of the esophagus and hypopharynx exist. Congenital diverticula are diverticula that are present at birth, while acquired diverticula develop later in life. Diverticula of the esophageal body can sometimes be difficult to classify as congenital or acquired.

Diverticula also may be classified on the basis of histopathology. True diverticula contain all layers of the intestinal tract wall. False diverticula, also known as pseudodiverticula, occur when herniation of mucosa and submucosa through a defect in the muscular wall occurs (eg, Zenker diverticulum). A special type of pseudodiverticula, believed to represent dilated excretory ducts of esophageal submucosal glands, is observed in the condition esophageal intramural pseudodiverticulosis.

Finally, acquired diverticula of the esophagus and hypopharynx also may be classified according to their pathogenesis as pulsion diverticula or traction diverticula. Pulsion diverticula form as a result of high intraluminal pressures against weaknesses in the GI tract wall. Zenker diverticulum occurs due to increased pressure in the oropharynx during swallowing against a closed upper esophageal sphincter. An epiphrenic diverticulum occurs from increased pressure during esophageal propulsive contractions against a closed lower esophageal sphincter. In contrast, traction diverticula occur as a consequence of pulling forces on the outside of the esophagus from an adjacent inflammatory process (eg, involvement of inflamed mediastinal lymph nodes in tuberculosis or histoplasmosis).

Age

Most esophageal diverticula occur in middle-aged adults and elderly people. Presentation in infants and children is rarely seen.

Zenker diverticula typically present in people older than 50 years and especially present during the seventh and eighth decades of life.

Clinical

History

• Zenker diverticula (see Media files 1-2) are formed by the herniation of mucosa through an area of weakness in the posterior wall of the hypopharynx (the Killian triangle).
  • Sometimes Zenker diverticula are called pharyngoesophageal diverticula because of their close proximity to the cervical esophagus; however, this is somewhat of a misnomer because the diverticula actually arise from the hypopharynx rather than from the esophagus.
  • Of the diverticula discussed in this article, Zenker diverticula are the most common type to cause symptoms.
  • Zenker diverticula are an acquired pulsion-type of diverticula that probably develop because of the aging process. They form in the posterior hypopharynx at a point where a defect in the muscular wall, between the inferior pharyngeal constrictor muscle and the cricopharyngeal sphincter (Killian triangle), usually exists.
  • Zenker diverticula are believed to occur because of an outflow obstruction caused when loss of coordination of the buccal squirt (ie, swallowing movement of the tongue posteriorly with contraction of the oropharyngeal muscles) and opening of the cricopharyngeus (ie, the upper esophageal sphincter) occurs. The noncompliant cricopharyngeus muscle becomes fibrotic over time.
  • Oropharyngeal dysphagia, usually to solids and to liquids, is the most common symptom. Retention of food material and secretions in the diverticulum, particularly when diverticula are large, can result in regurgitation of undigested food, halitosis, cough, and even aspiration pneumonia. The patient may note food on the pillow upon awakening in the morning. With very large diverticula, a mass in the neck occasionally can be detected. Cancer rarely has been reported in association with Zenker diverticula.
• Diverticula of the esophageal body are relatively rare. They primarily occur in the middle and distal esophagus (see Media file 3).
  • Diverticula that occur in the distal esophagus, in the lower 6-10 cm, are termed epiphrenic diverticula (see Media file 4).
  • Diverticula of the mid and distal esophagus may have various etiologies. For instance, some diverticula in the mid esophagus are congenital in origin; others are of the traction variety. With the latter, diverticula develop by traction from contiguous mediastinal inflammation and adenopathy, eg, pulmonary tuberculosis and histoplasmosis. The diverticula that develop by traction and adenopathy usually are asymptomatic.
  • Retention of undigested food in large diverticula occasionally results in regurgitation, nocturnal cough, and aspiration pneumonia.
  • Occasional epiphrenic diverticula occur in the setting of long-standing peptic esophagitis and strictures, and they rarely are symptomatic. Other rare causes of diverticula of the mid and distal esophagus include iatrogenic surgical injury to the esophagus and Ehlers-Danlos syndrome (weakness of collagen). Perhaps the most common causes of mid esophageal and epiphrenic diverticula are motility disorders of the esophageal body, including achalasia, diffuse esophageal spasm, and hypertensive lower esophageal sphincter.
  • Dysphagia is the most common symptom associated with mid esophageal and epiphrenic diverticula, although it usually is related more to the underlying motility disturbance than to the diverticulum per se. However, on occasion, the diverticulum may be responsible for the dysphagia, particularly if it is very large and filled with food or a bezoar. Regurgitation and aspiration may be related to large mid esophageal and epiphrenic diverticula; however, in patients with achalasia, regurgitation and aspiration are more likely to be related to poor esophageal emptying from the underlying motility disturbance (eg, hypertensive lower esophageal sphincter that fails to relax, absence of esophageal body peristalsis).
• Esophageal intramural pseudodiverticulosis is a very rare condition in which numerous 1- to 4-mm, saccular, flask-shaped outpouchings form in the wall of the esophagus (see Media files 5-6). Pseudodiverticula can number from a few to a hundred or more. This condition can be segmental or diffuse. About 200 cases have been reported in the literature.
  • Pseudodiverticula are formed by dilatation of the esophageal submucosal glands that communicate with the esophageal lumen.
  • Esophageal intraluminal pseudodiverticulosis generally is believed to be an acquired condition. While the precise pathogenesis is uncertain, inflammation and stasis appear to be factors. One hypothesis states that blockage of intramural ducts by inflammatory debris results in dilation of the submucosal glands.
  • Most patients with esophageal intraluminal pseudodiverticulosis have underlying esophageal strictures or dysmotility of the esophageal body. Esophageal intraluminal pseudodiverticulosis also has been reported as a consequence of corrosive injury to the esophagus, although most patients have associated strictures.
  • Dysphagia is the most common symptom associated with esophageal intramural pseudodiverticulosis. In most cases, esophageal intraluminal pseudodiverticulosis is related to the associated esophageal stricture or dysmotility.
  • An isolated case report cited significant bleeding from a distal esophageal diverticulum. The authors speculated that the bleeding resulted from food stasis, bacterial overgrowth, or chronic inflammation.
• See related CME at Diagnostic Evaluation of Dysphagia.
• See related CME at Treatment Options for Esophageal Strictures.

Physical

• Findings on physical examination often are normal in patients with symptomatic esophageal diverticula. However, many patients relate a history of dysphagia, chest pain, or regurgitation.
• Although the physical examination findings are often normal, a large Zenker diverticulum may present as a neck mass on physical examination. Halitosis also may be present and is secondary to accumulated food debris or medicines within the diverticulum.
• Signs and symptoms of aspiration pneumonia may accompany the presence of large symptomatic diverticula.

Causes

• Most diverticula are caused by an underlying motility disorder of the esophagus.
• Structural lesions, including a noncompliant cricopharyngeus muscle (ie, Zenker diverticulum), incomplete or uncoordinated relaxation of the lower esophageal sphincter, or strictures, may play a role as well.
• An underlying inflammatory process within the mediastinum has been associated with mid esophageal diverticula.