Zenkers Diverticulum

A Zenker's diverticulum is an acquired outpouching of the pharyn-goesophageal junction. It arises because of an inherent weakness in the posterior wall of the upper esophageal sphincter, the cricopharyngeus muscle. This area, called Killian's dehiscence, marks the junction of the oblique and transverse muscle fibers of that muscle. Zenker's divertic-ula may present with dysphagia, regurgitation of undigested ingested food, or aspiration pneumonia. Therapy is aimed at reducing or eliminating contents retained in the diverticulum and relieving the dysphagia.

Various surgical procedures have been proposed for the treatment of Zenker's diverticulum. The abalation of the diverticulum and/or its lumen is the aim of each. In very small diverticula, the performance of a cricopharyngeal myotomy may reduce the diverticulum to a small bulge in the mucosa, of no clinical significance [23]. When somewhat larger, the diverticulum may be suspended from the prevertebral fascia by a diverticulopexy. This procedure does not remove the diverticulum but, with the patient in the upright position, prevents the retention in its lumen of foodstuff and saliva. Therefore, there is little or no risk of overflow aspiration. A diverticulectomy actually removes the out-pouching. The base of a hand-sewn diverticular site is flat, while the use of a mechanical stapler often leaves a small mucosal outpouching (Fig. 2.8). The diverticulectomy is usually accompanied by a cricopha-ryngeal myotomy. In patients with contraindications for open surgery, there is an endoscopic alternative [24]. In this procedure an endoscopic stapler is placed with one limb in the diverticulum and the other in the esophageal lumen. When fired, the posterior wall between the diver-ticulum and esophageal lumen is stapled and divided, creating a wide open mucosal bulge that theoretically empties better and does not trap

Figure 2.8. Stapled Zenker's diverticulectomy. Lateral film of the soft tissues of the neck following a stapled Zenker's diverticulectomy. Note the thin linear collection of air posterior to the staple line, a normal feature following a stapled procedure.

as much food as the original diverticulum. Some authors believe that this is actually the procedure of choice for most patients [25].

In the immediate postoperative period, small pharyngocutaneous fistulas from the cricopharyngeal myotomy site to the skin may be observed. Additional small areas of extravasation related to the myotomy may be seen without communication to the skin [4]. The pharyngoesophageal segment may be deviated anteriorly secondary to prevertebral soft tissue edema.

Follow-up exams many months to years later show no significant pharyngoesophageal deviation or residual fistulae [4]. A deformity along the left posterolateral aspect of the pharyngoesophageal segment may persist at the site of the cricopharyngeal myotomy [4]. A persistent posterior bulge, representing the cricopharyngeal muscle, may be seen protruding into the pharyngoesophageal segment despite the performance of an adequate myotomy. This was not evident in the immediate postoperative period and most likely is secondary to cricopharyngeal muscle regeneration.

Videofluoroscopic evaluation of patients after Zenker's diverticulec-tomy is not usually performed. However, one study of 15 patients revealed a marked array of swallowing abnormalities [26]. The most commonly identified problems included subepiglottic aspiration, failure of peristaltic contractions to progress from the pharynx to the esophagus, and dilatation or stenosis at the pharyngoesophageal junction, each in more than 90% of patients studied. Even in patients whose symptoms improved postoperatively, a large number of the same swallowing abnormalities were identified. Therefore, Zenker's divertic-ulectomy with cricopharyngeal myotomy is effective in improving or alleviating symptoms without correcting the underlying abnormal physiology of swallowing. This dichotomy of symptoms and objective findings hinders the evaluation and comparison of the techniques just described.

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