Zenker's diverticulum overview

# Overview
In anatomy, Zenker's diverticulum, also pharyngoesophageal diverticulum, also pharyngeal pouch, is a diverticulum of the mucosa of the pharynx, just above the cricopharyngeal muscle (i.e. above the upper sphincter of the esophagus). It is a false diverticulum (not involving all layers of the esophageal wall). The first description of Zenker's diverticulum dates back to 1769 by Ludlow. It was named in 1877 by German pathologist Friedrich Albert von Zenker. Esophageal diverticula are classified on the basis of  location into three types: phrenoesophageal (Zenker's diverticulum-70%) ZD, epiphrenic (20%), thoracic and mediastinal (10%). Zenker's diverticulum is thought to be due to the result of motor abnormalities of the esophagus. The defect over the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx results in ZD. Killian's triangle leads to an evagination of the sphincter, which may be because of the high pressures in the food bolus in the course of swallowing and the abnormalities of the upper esophageal sphincter (UES). This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the hypopharyngeal pressure gradient. As the diverticulum enlarges, it may compress the pharyngoesophageal segment as well as increased stiffness and the intrabolus pressure. The risk factors of the Zenker's diverticulum include people in their seventh and eight decades, male, GERD, pre-existing hiatal hernia, esophageal motility disorder, esophagitis, neurological disorders like a stroke. Symptoms of Zenker's diverticulum slowly start as a oropharyngeal dysphagia progressing from solids to liquids, Regurgitation of undigested food from the diverticular sac, Pharyngeal stasis of secretions, Chronic aspiration, Halitosis, Chronic cough, sensation of a lump in the throat, Hoarseness, Cervical borborygmi. Aspiration pneumonia, Bleeding of the diverticulum, Ulceration of the diverticulum, compression of the trachea and esophageal obstruction with large diverticula, very rarely Squamous cell carcinoma of the diverticulum, Perforation of the diverticulum during the endoscopy and hence scopes with side viewing should be used to prevent perforation. While it may be asymptomatic, Zenker diverticulum often causes clinical manifestations such as dysphagia, globus sensation, regurgitation, cough, halitosis, and odynophagia. An x-ray (barium esophagogram) is the best initial imaging study in a patient suspected with Zenker's Diverticulum. Findings on an x-ray (barium esophagogram) suggestive of esophageal diverticulum associated with ZD appear as thin projections on the anterior esophageal wall over the Killian's triangle. No medical treatment is currently known or practiced for symptomatic Zenker diverticulum. Surgery is the most definitive therapy for the Zenker's diverticulum. If small and asymptomatic, no treatment is necessary. Larger, symptomatic cases of Zenker's diverticulum have been traditionally treated by neck surgery to resect the diverticulum and incise the cricopharyngeus muscle. However, in recent times non-surgical endoscopic techniques have gained more importance, and the currently preferred treatment is the endoscopic stapling i.e. closing of the diverticulum via a stapler inserted through a tube in the mouth. This may be performed through a fiberoptic endoscope. Other non-surgical treatment modalities exist, such as endoscopic laser, which recent evidence suggests is less effective than stapling.

# Historical Perspective
The first description of Zenker's diverticulum dates back to 1769 by Ludlow. It was named in 1877 by German pathologist Friedrich Albert von Zenker. The first description of Zenker's diverticulum dates back to 1769 by Ludlow. A century later, a German pathologist, Friedrich Albert von Zenker, recognized and further characterized the pathophysiology of this diverticulum. In 1877 Zenker and Ziemssen reviewed the world literature on the Zenker's diverticulum. In 1840 Rokitansky first described traction diverticula of the thoracic esophagus. Until 1816 publication,ZD was thought to be congenital or traumatic in origin. In 1877, von Zeimssen, professor in Munich, published "Krankheiten des Oesophagus" on the esophageal ulceration and  diverticula. Preliminary thoughts on managing pharyngoesophageal diverticula originated as early as 1830, when Bell proposed the establishment of a fistula to empty the diverticulum of its contents.

# Classification
Esophageal diverticula are classified on the basis of  location into three types Phrenoesophageal (Zenker's diverticulum-70%) ZD is a defect over the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx. Epiphrenic (20%) diverticula result either from hypertonia of the lower esophageal sphincter (esophageal achalasia). Thoracic and mediastinal (10%) Thoracic diverticula are probably more often of a congenital than traction origin.

# Pathophysiology
Zenker's diverticulum (ZD) is thought to be due to the result of motor abnormalities of the esophagus. The defect over the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx results in ZD. Killian's triangle is surrounded by the cricopharyngeal sphincter and oblique fibers of the inferior constrictor of the pharyngeal muscle. It is considered a pseudodiverticulum as it includes only mucosa and submucosa. Chronic strain on the Killian's triangle leads to an evagination of the sphincter, which may be because of the high pressures in the food bolus in the course of swallowing and the abnormalities of the upper esophageal sphincter (UES). This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the hypopharyngeal pressure gradient. Increased intra-bolus pressures found in patients with ZD can be secondary to impaired bolus passage combined with the gastroesophageal reflux disease (GERD) or as a result of the GERD. As the diverticulum enlarges, it may compress the pharyngoesophageal segment as well as increased stiffness and the intrabolus pressure. Increased intrabolus pressure is also increased in older patients who perform multiple swallows to achieve bolus clearance. Acid reflux is thought to lead to increased spasm of the UES which in turn increases the intra-bolus pressures during swallowing, given that swallowing is frequently distinct from episodes of acid reflux disease.

# Causes
Zenker's diverticulum (ZD) also known as pharyngosophageal diverticulum. It is an acquired sac-like outpouching of the mucosa and submucosa layers originating from the pharyngoesophageal junction. Killian's dehiscence a pulsion of false diverticulum occurring dorsally at the pharyngoesophageal wall surrounded by the oblique inferior pharyngeal constrictor muscle and the transversal fibers of the cricopharyngeal muscle. ZD occurs due to increased intraluminal pressure in the oropharynx during swallowing, against an inadequate relaxation of the cricopharyngeal muscle. An incomplete opening of the Upper Esophageal Sphincter (UES) causing the protrusion of the mucosa through an area of relative weakness at the dorsal pharyngoesophageal wall. The pharyngoesophageal phase of swallowing is affected in ZD resulting in hindering the neuromuscular functions such as chewing, initiating the swallowing, and propulsion of the food from the oropharynx into the cervical esophagus.

# Differentiating Zenker's diverticulum from Other Diseases
The differential diagnosis of the Zenker's diverticulum (ZD) are as follows Plummer-Vinson syndrome, reflux esophagitis, esophageal carcinoma, systemic sclerosis, achalasia, psuedoachalasia, chagas disease, esophageal candidiasis, pharyngitis and stroke.

# Epidemiology and Demographics
The incidence ZD is approximately 2 per 100,000 individuals worldwide, The prevalence of ZD is between 0.01 to 0.11% per 100,000 individuals worldwide. The mortality rate is 0.3% for stapled rigid endoscopic procedures. Mortality rate for non-stapled rigid endoscopic procedures is 0.2%. ZD commonly affects middle-aged and elderly individuals, especially people in their 7th and 8th decades.There is no racial predilection to ZD. Males are more commonly affected by ZD than females. The men to women ratio is approximately 1.5 to 1. The majority of ZD cases are reported in northern Europe.

# Risk Factors
The risk factors of the Zenker's diverticulum (ZD) are as follow people in their seventh and eight decades, male, GERD, pre-existing hiatal hernia, esophageal motility disorder, esophagitis, neurological disorders like a stroke.

# Screening
There is insufficient evidence to recommend routine screening for Zenker's diverticulum.

# Natural History, Complications, and Prognosis

## Natural History
Symptoms of Zenker's diverticulum slowly start as a oropharyngeal dysphagia progressing from solids to liquids, Regurgitation of undigested food from the diverticular sac, Pharyngeal stasis of secretions, Chronic aspiration, Halitosis, Chronic cough, sensation of a lump in the throat, Hoarseness, Cervical borborygmi. The patient may note food on the pillow upon awakening in the morning. Although small diverticula may not cause symptoms, larger diverticula usually are symptomatic. Both the inability of the sphincter to fully open and the extrinsic compression from the pouch itself are likely to explain the dysphagia experienced by patients. In patients with very large diverticula, a gurgling swelling in the neck can occasionally be detected on palpation.

## Complications
Complications of the Zenker's diverticulum includes Aspiration pneumonia, Bleeding of the diverticulum, Uuceration of the diverticulum, compression of the trachea and esophageal obstruction with large diverticula, very rarely Squamous cell carcinoma of the diverticulum, Perforation of the diverticulum during the endoscopy and hence scopes with side viewing should be used to prevent perforation.

## Prognosis
Prognosis of ZD after the intervention is good, the recurrence of the diverticulum is very rare.

# Diagnosis

## Diagnostic Criteria

## History and Symptoms
While it may be asymptomatic, Zenker diverticulum often causes clinical manifestations such as dysphagia, globus sensation, regurgitation, cough, halitosis,odynophagia.

## Physical Examination
While it may be asymptomatic, Zenker diverticulum often causes clinical manifestations such as Dysphagia, Globus sensation, Regurgitation, Cough, Halitosis, Odynophagia.

## Laboratory Findings
Laboratory studies are not helpful in the diagnosis of the Zenker's Diverticulum (ZD), whereas they are used for the upper esophageal webs associated with iron deficiency anemia. The laboratory tests are done to differentiate the ZD from Plummer- Vinson syndrome. Laboratory findings consistent with the diagnosis of Plummer-Vinson syndrome include the presence of iron deficiency anemia.

## Imaging Findings

# X-ray
An x-ray (barium esophagogram) is the best initial imaging study in a patient suspected with Zenker's Diverticulum (ZD). Findings on an x-ray (barium esophagogram) suggestive of esophageal diverticulum associated with ZD appear as thin projections on the anterior esophageal wall over the Killian's triangle.

# CT scan
Zenker's diverticulum appears as an out-pouching sac on the CT scan over the posterior esophagus in the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx surrounded by the cricopharyngeal sphincter and oblique fibers of the inferior constrictor of the pharyngeal muscle.

# MRI
Zenker's diverticulum appears as an out-pouching sac on the MRI scan over the posterior esophagus in the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx surrounded by the cricopharyngeal sphincter and oblique fibers of the inferior constrictor of the pharyngeal muscle. The sac is filled with, fluid, food, contrast materials.

## Other Diagnostic Studies

# Treatment

## Medical Therapy
No medical treatment is currently known or practiced for symptomatic Zenker diverticulum.

## Surgery
Surgery is the most definitive therapy for the Zenker's diverticulum (ZD). If small and asymptomatic, no treatment is necessary. Larger, symptomatic cases of Zenker's diverticulum have been traditionally treated by neck surgery to resect the diverticulum and incise the cricopharyngeus muscle. However, in recent times non-surgical endoscopic techniques have gained more importance, and the currently preferred treatment is the endoscopic stapling i.e. closing of the diverticulum via a stapler inserted through a tube in the mouth. This may be performed through a fiberoptic endoscope. Other non-surgical treatment modalities exist, such as endoscopic laser, which recent evidence suggests it less effective than stapling.

## Prevention
There are no established measures for the primary prevention of Zenker's Diverticulum.