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Esophageal Diverticula
Based on radiologic and endoscopic studies, esophageal diverticula have a prevalence of up to 3% of individuals. They may be classified according to cause (pulsion or traction), location (pharyngoesophageal, midesophageal, or epiphrenic), or wall component (full thickness [true diverticula] or mucosal/submucosal [pseudodiverticula]) ( Fig. 5.1 ). Zenker diverticula account for 70% of all esophageal diverticula.
Esophageal Diverticula.
Cricopharyngeal Diverticula
Zenker, or pharyngoesophageal, diverticula occur 10 times more often than other esophageal diverticula; 80% to 90% of cases occur in men, and the average age is 50 years. Predisposing factors may include esophageal dysmotility, a shortened esophagus, as well as dysfunction of the upper esophageal sphincter (UES). Zenker diverticula develop as the mucosa and submucosa of the hypopharynx herniate between the inferior constrictor and the cricopharyngeal muscles in the posterior midline. This area is known as the Killian triangle. The developing sac becomes stretched over time as it protrudes to the left, posterior to the esophagus, and anterior to the prevertebral fascia. Evidence suggests that patients with Zenker diverticula have more scar tissue and that degenerated muscle fibers of the cricopharynx have a smaller opening and increased hypopharyngeal bolus pressure during swallowing. Changes in the morphology of the unique fiber orientation of the cricopharyngeal muscle may impair its dilation and are thought to be caused by progressive denervation of the muscle.
Clinical Picture
Initially patients may have the sensation of a lump in the throat and may accumulate copious amounts of mucus. Patients may report foul-tasting food, halitosis, and nausea. Dysphagia to liquids and eventually dysphagia to solids may occur. Patients may regurgitate undigested food when coughing, and some may develop aspiration pneumonia or a lung abscess. As the disease progresses, obstruction may result in significant weight loss and malnutrition.
Diagnosis
On examination there is usually fullness under the left sternocleidomastoid muscle, with resultant gurgling on compression. Barium esophagraphy may demonstrate the size, location, and degree of distention of the diverticulum. Esophagoscopy reveals a wide mouth pouch that ends blindly as well as two lumens above the cricopharyngeal muscle. The opening of the esophagus may be pushed anteriorly and kinked by the diverticulum. The manometry pattern may demonstrate findings consistent with dysmotility of the UES and may differentiate dysphagia secondary to a recent cerebrovascular accident (stroke).
Treatment, Management, Course, and Prognosis
Treatment for a Zenker diverticulum is surgical, by either an open external cervical or minimally invasive approach. Endoscopic approaches employ either a rigid endoscope and stapler or a flexible endoscope. All techniques to treat Zenker diverticula include a cricopharyngeal myotomy. Minimally invasive approaches depend on the availability of a surgeon skilled in these techniques. Open surgery has been associated with increased morbidity from both its invasive nature and the morbidity of the patient population.
Open surgery for a Zenker diverticulum includes diverticulectomy, invagination, diverticulopexy, and myotomy. Morbidity ranges from 3% for myotomy to 23% for diverticulectomy with myotomy. Significant improvement occurs in 92% of patients; 6% experience recurrence with diverticulectomy, and 21% have recurrence with invagination. Open techniques result in better symptomatic relief than endoscopic staple diverticulostomy (ESD), especially in patients with small diverticula. Resection without myotomy is initially effective but may result in recurrence or fistulas in the long term.
The ESD procedure is a minimally invasive or endoscopic approach. Flexible endoscopy techniques were first reported in 1995. ESD may be performed in up to 85% of patients with Zenker diverticula, although a large diverticulum with redundant mucosa is a risk factor for recurrence. A linear stapler is placed with one blade in the esophagus and the other in the diverticulum as the stapler is fired across the cricopharyngeal muscle. ESD is a safe, effective procedure with a high level of patient satisfaction. The morbidity rate is 2% to 13% with staplers. The recurrence rate is 12%, but it is as high as 64% in some studies.
Flexible endoscopy procedures involve coagulation and cutting of the cricopharyngeal muscle shared by the esophagus and the diverticulum, allowing flow of substances from the diverticulum into the esophagus. The midline of the septum is cut using this technique. The procedure can be performed under light or deep sedation. If bleeding or microperforations occur, they can be treated using endoclips. After more than 2 years, there is a 77% to 95% complete resolution of symptoms. Esophageal microperforation occurs in 3% to 19%, but 82% resolve with conservative treatment. There is a 15% symptom recurrence rate.
Generally patients recover and return to their normal diets quickly, and complication and mortality rates are lower than with open procedures. When ESD is compared with other endoscopic procedures, duration of surgery and mortality rates are similar, but there are fewer complications and a quicker convalescence with ESD.
Small diverticula may be treated by diverticulectomy with or without myotomy. Large diverticula may be treated by any of the mentioned methods. Patients younger than 60 years of age or those with very large diverticula should undergo diverticulectomy. Elderly patients with multiple comorbidities should be treated by ESD.
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