Schatzki ring

# Overview
A Schatzki ring or Schatzki-Gary ring is a ring found in the lower part of the esophagus that can cause difficulty swallowing.  The ring is made up of mucosal tissue (which lines the esophagus) or muscular tissue.  Patients with Schatzki rings can develop intermittent dysphagia (difficulty swallowing), or, more seriously, a completely blocked esophagus. The ring is named after the American physician Richard Schatzki.

# Clinical presentation
Not all patients with Schatzki rings have symptoms; indeed, barium swallow tests of the esophagus will sometimes show Schatzki rings in patients who have no symptoms.  When Schatzki rings cause symptoms, they usually result in episodic dysphagia with solid foods, or a sensation that the food "sticks" while swallowing.  This particularly occurs if the food is not chewed thoroughly.  Cases of complete obstruction have been called steakhouse syndrome: during a meal, there is a bolus obstruction of the esophagus with the foodstuff, resulting in acute crushing chest pain and dysphagia.  Patients usually are able to regurgitate or force through the food material, but may need immediate treatment with endoscopy, which is the use of a specialized fibre-optic camera in order to remove the lodged food.  This involves urgent endoscopy to locate the obstruction, followed by the insertion of devices to either pull the food out of the esophagus, or to push it into the stomach.  The latter is usually done only with caution, or if the anatomy of the structures where the obstruction occurred is already known.  Snares and forceps passed through the endoscope can be used for these purposes.

# Diagnosis
When a patient has a suspect Schatzki ring, the physician can make the diagnosis by doing one of two tests: either an esophagogastroduodenoscopy or barium swallow.  The endoscopy typically shows a ring within the lumen of the esophagus which can be of variable size.  The ring is typically located a few centimetres above the gastro-esophageal junction, which joins the stomach and the esophagus.  Schatzki rings can often resemble a related entity, called an esophageal web.  Esophageal webs are similar in that they also contain extra mucosal tissue, but they do not completely encircle the esophagus.
Endoscopies and barium swallows done for other reasons often show evidence of Schatzki rings, meaning that many Schatzki rings are asymptomatic.
Two varieties of Schatzki rings have been described.  The original description by Schatzki and Gary was of a ring of fibrous tissue seen on autopsy; this is the far less common type of Schatzki ring.  More commonly, the ring consists the same mucosal tissue that lines the entire esophagus.  Many hypotheses have been raised as to the cause of the Schatzki rings, but the cause is uncertain, and may be related to both congenital and acquired factors.

# Treatment
If asymptomatic, there is evidence that Schatzki rings do not progress to cause symptoms, and no treatment is suggested.
Symptomatic Schatzki rings may be treated with esophageal dilatation, either using bougie or balloon dilators.  These have been found to be equally effective.  Bougie dilatation involves the passage of long dilating tubes of increasing size down the esophagus to stretch the area of narrowing.  This is either done over a guidewire passed into the stomach by endoscopy (the Savary-Gillard system) or using mercury-weighted dilators (the Maloney system).  This is usually done with intravenous sedation to ensure comfort.  The duration of the effect of dilation varies between individuals, but may be from months to years.  Dilation may need to be repeated if further narrowing at the site of the ring occurs over time.
After treatment with dilatation or endoscopic management of a bolus obstruction, there is often some trauma associated with the procedure.  A short course of proton pump inhibitor therapy may be given to decrease stomach acid reflux into the esophagus, which may aggravate the area of trauma.

# Other associations
- Schatzki rings can be associated with swallowing syncope, a rare variety of syncope.
- Schatzki rings are associated with a decreased incidence of Barrett's esophagus, which is considered to be a pre-cancerous condition of the esophagus in some cases.