DIVERTICULA

An esophageal diverticulum is a pouch or sac created by herniation of the lining mucous membrane through the muscular wall. A true diverticulum exists if all layers of the esophageal wall are represented within the diverticulum. A false or pseudodiverticulum consists only of mucosa and submucosa. Typically, diverticula are classified by anatomic location: pharyngoesophageal, mid-esophageal or mid-thoracic, and epiphrenic. In addition, they may be categorized by their pathophysiology as pulsion or traction types of diverticula. Pulsion diverticula are associated with elevated intraluminal pressure, whereas traction diverticula arise from extraluminal tugging by adjacent sites of inflammation and fibrosis.

A Zenker diverticulum is a pharyngoesophageal pseudodiverticulum of the pulsion type. It represents a herniation through a weak area between the inferior pharyngeal constrictor fibers and the cricopharyngeus muscle. The region of this muscular weakness is known as a Killian dehiscence or triangle. The mechanism of development for this diverticulum has been the subject of considerable debate. Hypotheses include increased intraluminal pressure, increased cricopharyngeal tone, and incoordination of UES contraction and relaxation.

Zenker diverticula are most often seen in the sixth through ninth decades of life. Men are affected two to three times more often than women. A history of long-standing dysphagia with an insidious onset is typical. Retention in the diverticulum may lead to spontaneous regurgitation and can be accompanied by symptoms of aspiration. With progressive enlargement, the diverticulum may eventually compress the normal esophageal lumen, increasing dysphagia and producing symptoms of obstruction. The physical examination is usually unremarkable, although manual compression of the neck may elicit a gurgling sensation or crepitus in some patients.

The diagnosis is easily confirmed on barium swallow. Generally, as a Zenker diverticulum enlarges, it extends inferiorly between the esophagus and vertebral column, usually on the left (Fig. 56.5). Radiographic defects within the pouch usually represent retained food material, although tumor is a rarely encountered phenomenon.

FIGURE 56.5. Large, contrast-filled Zenker diverticulum.

Small, asymptomatic diverticula require no intervention. Numerous surgical options exist, however, for those requiring treatment due to symptomatic disease. Endoscopic management of Zenker diverticula has become increasingly popular. The original technique, known as the Dohlman procedure, required diathermy and a bivalved esophageal speculum. With one blade in the esophagus and the other in the pouch, the common wall (which includes the cricopharyngeal muscle) was removed sequentially with diathermy instruments. A modification of this technique using the microscope and cO2 laser was introduced by Van Overbeek, who reported

On 544 patients treated endoscopically with a minimum follow-up of 10 months. There were few complications, and 99.2% of the patients were highly or fairly satisfied with the results (21). Van Overbeek found that patients treated with CO2 laser excision of the diverticulum experienced less pain and less tendency toward stenosis

Than patients treated with electrocoagulation. Other modifications of the Dohlman procedure include flexible endoscopic techniques and endoscopic staple-assisted diverticulectomy.

Many head and neck surgeons prefer an open, transcervical approach for the treatment of Zenker diverticula (Fig. 56.6). Packing the diverticulum endoscopically with gauze is beneficial in identifying the pouch at surgery. Small diverticula (< 2 cm) can be managed adequately with cricopharyngeal myotomy alone, minimizing postoperative complications and morbidity. The muscular incision should be placed in the posterior midline to avoid recurrent laryngeal nerve injury. Larger diverticula require removal in combination with myotomy. Complications of surgery include hematoma, wound infection, leakage, fistula, mediastinitis and recurrent laryngeal nerve injury. Stenosis and recurrent diverticula also may occur. Diverticulopexy may be preferable in elderly patients for whom a more extensive procedure would significantly increase operative risk. With the patient under local anesthesia, the sac can be identified and "tacked up” to the prevertebral fascia, preventing retention of food products and the associated sequelae.

FIGURE 56.6. Transcervical diverticulectomy. A: Skin incision. B, C: Exposure of the pharynx and cervical esophagus. D, E: Dissection of the diverticulum with myotomy. F: Excision. G: Closure of the cervical esophagus. H: In selected cases, the diverticulum may be inverted and sutured to the prevertebral fascia (diverticulopexy).

Mid-esophageal diverticula are traction diverticula associated with inflammatory processes in the parabronchial region. These are true diverticula and typically are small and asymptomatic. Associated complications include diverticulitis, perforation, bleeding, and fistula formation. Barium swallow demonstrates a wide-mouthed diverticulum in the mid-portion of the esophagus. Surgery is reserved for patients with complications and consists of a right thoracotomy with excision of the diverticulum.

Epiphrenic diverticula represent an uncommon type of pulsion diverticula that arise from the lower esophagus, usually in the most distal 5- to 10-cm segment. They usually arise proximal to a mechanical or functional obstruction. They range in size from less than 1 cm to greater than 10 cm. There is a frequent association with other conditions, including hiatal hernia with reflux esophagitis, diffuse esophageal spasm, achalasia, and carcinoma of the esophagus. Some researchers suggest that an area of congenital weakness exists in the wall of the distal esophagus, which produces outpouching in response to prolonged increases in intraluminal pressure.

The predominant symptoms are dysphagia and regurgitation, although obstruction may occur with large diverticula. Endoscopy may be helpful in evaluating associated conditions, but must be performed with extreme caution to prevent perforation of the thin-walled diverticulum. In symptomatic patients, surgery consists of diverticulectomy and correction of any underlying esophageal disorder.

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