Describe pharyngeal pouch.

Nature and Presentation

• A pharyngeal pouch (ZENKER’S diverticulum) is a pulsion diverticulum of pharyngeal mucosa herniating through killian’S dehiscence — the weak area between thyropharyngeus and cricopharyngeus.
• It is therefore a false diverticulum, containing mucosa and submucosa but NO muscle.
• The pathogenesis IS A failure OF coordination rather than of anatomy alone — cricopharyngeus fails to relax in time during swallowing (or is hypertensive), so pressure rises in the hypopharynx and the mucosa herniates through the weakest point above it
• Reduced cricopharyngeal compliance and fibrosis, and an association with gastro-oesophageal reflux, are contributory
• It is a disease of the elderly, over 70, and commoner in men
• The pouch develops posteriorly and then, as it enlarges, deviates to one side — the left.
• The symptoms follow its size, and describing that progression is the clearest way to answer:
• Early — a vague sensation of something in the throat, throat clearing, and intermittent dysphagia
• Established — dysphagia; regurgitation of undigested, unaltered food eaten hours or days earlier.

Investigation and Treatment

• A barium swallow is the investigation of choice, and demonstrates the pouch, its size and the level of its neck. Video-fluoroscopy with lateral views is best.
• Endoscopy must be performed with great caution.
• Hence the rule: obtain the barium study before endoscopy where a pouch is suspected
• Also assess — nutritional state, chest imaging for aspiration, and fitness for anaesthesia.
• Treatment is surgical, and the essential component is division of cricopharyngeus
• This IS the key principle OF the whole topic: the myotomy treats the cause (the failure of relaxation).
• Endoscopic stapling (dohlman procedure, or endoscopic diverticulotomy) is now the procedure of choice for most patients — a stapling device or laser divides the common wall (the party wall) between the pouch and the oesophagus.
• Its advantages — no external incision, shorter operating time and hospital stay, earlier feeding, less pain, and much lower morbidity.
• Its limitations — it requires adequate neck extension and mouth opening, so it is unsuitable where there is cervical spine disease, kyphosis or trismus; it is less suitable for a very small pouch (too little common wall) or a very large one; and it leaves a residual pouch, with a higher rate of recurrence than open surgery
• Open (external) surgery through a left-sided neck incision — with cricopharyngeal myotomy plus diverticulectomy, diverticulopexy (suspending the pouch upward so it drains) or invagination