Pharyngeal pouch

Synonym: Zenker's diverticulum

A pharyngeal pouch represents a posteromedial pulsion diverticulum through Killian's dehiscence. It is a herniation between the thyropharyngeus and cricopharyngeus muscles that are both part of the inferior constrictor of the pharynx.

The aetiology is unknown¹. However, malfunction of the upper oesophageal sphincter probably contributes. A diagrammatic representation of the anatomy can be found in the Surgical Tutor reference².

Epidemiology

It is uncommon but the incidence appears to be higher in Northern Europe than elsewhere³. It is largely confined to those aged over 70 years and males outnumber females by 5:1.

Presentation

The usual presenting features are dysphagia, regurgitation, aspiration, chronic cough and weight loss⁴. Usually there are no clinical signs but there may be a lump in the neck that gurgles on palpation. There may also be halitosis from food decaying in the pouch.

Differential diagnosis

Usually this is the differential diagnosis of dysphagia and must include oesophageal carcinoma and oesophageal strictures, webs and rings.

Investigations

Endoscopy should be avoided as an initial investigation for fear of perforating the lesion. A barium swallow may show a residual pool of contrast within the pouch.

Indirect laryngoscopy may show a pooling of saliva within the pyriform fossa.

Management

This is dependent upon the size of the pouch. With recognition of the importance of the cricopharyngeus muscle in the pathogenesis of the pouch, the emphasis on treatment has shifted from diverticulectomy to cricopharyngeal myotomy. Minimally invasive techniques have become established with endoscopic stapling devices⁵. There is no clear evidence whether one endoscopic procedure is superior to another⁶.

Diverticulectomy

This is used for larger lesions. A rigid endoscope is passed and the pouch is packed with gauze. An incision is made at the level of the cricoid cartilage and the fascia at the anterior border of the sternomastoid is divided. The pouch is identified and excised and the defect closed. Cricopharyngeal myotomy is performed to prevent recurrence. The patient is fed via a nasogastric tube for a week postoperatively. Potential complications include:

• Recurrent laryngeal nerve palsy.

• Cervical emphysema.

• Mediastinitis.

• Cutaneous fistula.

Dohlman's procedure⁷

This is suitable for smaller lesions and is performed via an endoscope. A double-lipped oesophagoscope is used and the wall between the diverticulum and oesophageal wall is exposed. The hypopharyngeal bar is divided with diathermy or laser.

The advantages are that it is a minimally invasive technique that allows⁸:

• Shorter duration of anaesthesia.

• More rapid resumption of oral intake.

• Shorter hospital stay.

• Quicker recovery.

There is no evidence from high-quality randomised controlled trials to demonstrate the effectiveness of endoscopic compared with open procedures for pharyngeal pouch. There is no good evidence to establish whether one endoscopic procedure is superior to another⁶. There is some evidence that, whilst endoscopic surgery is safer for the elderly and frail, there may be a higher rate of recurrence and the conversion to an open procedure may be required if there are technical difficulties or perforation during operation⁹.

Complications

• Aspiration from the pouch can cause inhalation pneumonia.

• Carcinoma may develop in the pouch, although the true level of risk is debated⁴.

History

Friedrich Albert von Zenker was a German physician and pathologist. He was born in Dresden in 1825 and died in 1898. He studied at Leipzig and received his doctorate in 1851. His name is also attached to Zenker's degeneration: severe glassy or waxy hyaline degeneration or necrosis of skeletal muscles in acute infectious diseases, and to Zenker's paralysis: peroneal nerve palsy.