Introduction

A pharyngeal pouch (also known as a Zenker's diverticulum) is an outpouching of the pharyngeal mucosa through an area of muscular weakness at the posterior pharyngeal wall called Killian's dehiscence. It is a type of oesophageal diverticulum, which is an umbrella term also including midthoracic diverticula and epiphrenic diverticula.

Pharyngeal pouches occur in 1 in 200,000 people in the UK and typically affect older males. They are an important cause of dysphagia and are often associated with regurgitation, cough and halitosis.

Epidemiology

  • Incidence: 2.00 cases per 100,000 person-years
  • Peak incidence: 70+ years
  • Sex ratio: more common in males 5:1
Condition Relative
incidence
Gastro-oesophageal reflux disease2500.00
Oesophageal cancer5.00
Pharyngeal pouch1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

  • It is not known why some people develop pharyngeal pouches whilst others do not, however, some proposed mechanisms include:
    • Uncoordinated swallowing
    • Impaired relaxation of the cricopharyngeus muscle leading to increased pressure in the distal pharynx
    • Anatomical predisposition to larger Killian's dehiscence

  • Common risk factors include:
    • Older age: pharyngeal pouches are uncommon under the age of 40, and most commonly occur in the seventh decade of life or later
    • Male sex: pharyngeal pouches are 5 times more common in men
    • Positive family history: this may be related to having an anatomically larger Killian's dehiscence


Pathophysiology

  • A pharyngeal pouch is formed when pharyngeal mucosa herniates through a weak area of the posterior pharyngeal wall
    • This area is known as the Killian's dehiscence and is located between the cricopharyngeus and thyropharyngeus muscles (the muscles which form the upper oesophageal sphincter)


  • Over time, excessive pressure within the lower pharynx, caused by swallowing, can result in ballooning of the pharyngeal mucosa through Killian's dissidence, forming a pharyngeal pouch
    • Uncoordinated swallowing may contribute to this excessive pressure
    • A pharyngeal pouch may be several centimetres in diameter and grow over time
    • The pouch is known as a pseudodiverticulum as it does not involve all layers of the oesophageal wall

Clinical features

  • A pharyngeal pouch may be asymptomatic, however, patients typically present with:
    • Dysphagia (85%)
    • Regurgitation of food (40%)
    • Cough and aspiration (35%)
    • Halitosis
    • Neck swelling
    • Gurgling sound when swallowing
    • Weight loss due to eating difficulties

  • Physical examination findings may include:
    • A neck swelling which gurgles on palpation (Boyce's sign)
    • Signs of weight loss and/or malnutrition

  • Symptoms may develop over weeks or years and tend to worsen as the pharyngeal pouch grows larger

  • Sudden worsening of dysphagia and/or presence of haemoptysis may suggest malignancy within the pouch and should be investigated using a 2-week wait referral

Investigations

  • Patients presenting with dysphagia are referred for an oesophagoduodenoscopy (OGD) as an initial investigation
    • An OGD may be able to identify and assess the extent of a pharyngeal pouch if it is present

  • A barium swallow test is the gold standard investigation to confirm the presence of a pharyngeal pouch
    • A barium swallow test is also known as oesophagram and is often performed after an OGD if a pharyngeal pouch is suspected
    • The patient swallows liquid barium sulphate whilst X-ray images are taken
    • The barium will pool in the pharyngeal pouch and not move between films, as a food bolus would
    • This confirms the presence of a pharyngeal pouch

Differential diagnosis

The symptoms of a pharyngeal pouch can also be caused by many other pharyngeal and oesophageal conditions.

Possible differential diagnoses:
  • Gastro-oesophageal reflux (GORD)
    • Similarities: both may cause dysphagia, regurgitation and cough
    • Differences: GORD is more common and does not cause neck swelling or a gurgling sound
  • Diffuse oesophageal spasm
    • Similarities: both may cause dysphagia and regurgitation
    • Differences: the main presenting symptom of oesophageal spasm is often chest pain; neck swelling is not a feature
  • Oropharyngeal carcinoma
    • Similarities: both may cause dysphagia, regurgitation and weight loss; increasing age and male sex are risk factors for both
    • Differences: haemoptysis and local pain are alarm symptoms for oropharyngeal carcinoma, and there is typically a history of smoking and/or excessive alcohol consumption
  • Oesophageal achalasia
    • Similarities: both may cause dysphagia
    • Differences: achalasia typically causes retrosternal pain

Management

All patients with symptoms of a pharyngeal pouch should be referred to Ear, Nose and Throat (ENT) for assessment and management.

The mainstay management of a pharyngeal pouch is surgery, however, in patients with mild symptoms or those unable to have surgery, a 'watch-and-wait' approach may be more appropriate.

  • In 2015 NICE published guidelines on the surgical techniques approved for the management of pharyngeal pouch
    • Traditionally, open surgery is performed and the pouch is completely removed (called a diverticulectomy)
    • Endoscopic techniques using rigid endoscopes are now preferred to open surgery as they are quicker, less invasive, more cost-effective and tend to have a shorter recovery time
    • During endoscopic surgery, the pharyngeal pouch may be treated using a diathermy laser or stapling technique
    • Current guidelines recommend that open surgery should only be performed after 2 failed endoscopic surgeries, or if patients have any contraindications to endoscopic surgery, such as poor mobility of the cervical spine due to osteoarthritis

Complications

  • Malnutrition
    • Clinical malnutrition may be identified in up to 31% of patients with a pharyngeal pouch and is likely a result of dysphagia

  • Aspiration pneumonia
    • Up to 12% of patients with a pharyngeal pouch may develop an aspiration pneumonia

  • Small increased risk of squamous cell carcinoma within the pouch
    • This is a rare but important complication (reported incidence of up to 1.1%)
    • It is thought to be due to chronic inflammation of the mucosa within the pouch over time