The esophagus, also known as the gullet, is the long and narrow tube of the alimentary tract that leads from the throat to the stomach. It is located in the neck and chest cavity (thorax). Food and fluid when swallowed enters the esophagus and is rapidly propelled by esophageal contractions to reach the stomach. No digestion occurs in the esophagus but large amounts of mucus lubricates the chewed food.
The swallowing process is not separate in the throat and esophagus. The waves that start in the mouth and throat (oral and pharyngeal swallowing), continues throughout the esophagus until the food empties into the stomach. This is known as the esophageal stage of swallowing and is an important factor to consider when assessing problems with the esophagus. Motility comprises of peristaltic waves – primary and secondary – that need to carefully coordinated in order for food to reach the stomach as rapidly as possible.
A blockage of the esophagus may cause a number of symptoms including discomfort or pain when eating and swallowing (odynophagia), difficulty swallowing (dysphagia) and regurgitation. It is often asymptomatic in the early stages and initially patients only report a minor discomfort in the neck or chest or slight difficulty when swallowing. Regurgitation, loss of appetite and associated symptoms are not seen with a minor blockage.
Partial or Complete Blockage
Esophageal obstruction is usually gradual and in the early stages, a partial blockage may remain unnoticed. The obstruction may be due to :
- intrinsic factors – pathology of the esophagus itself like a mass, narrowing (stricture) or motility problems (dysmotility)
- extrinsic factors – compression from outside of the esophagus or CNS lesions
If esophageal clearance is hampered, the food may back up in the esophagus and lead to a dilated gullet (megaesophagus). The dilation arises proximal (before) to the site of the obstruction. Many of the causes of a blockage of the esophagus are discussed under esophageal strictures.
Food and Foreign Objects
Food and foreign objects may obstruct the normal healthy esophagus if it is large and inadequately broken down by chewing. In most cases the large particle never enters the esophagus because it either lodges within the throat or is pushed out. If it does pass the throat, the esophagus can stretch to accommodate it and normal esophageal motility will quickly push it into the stomach.
Sometimes slight narrowing of the esophageal lumen may go by unnoticed for long periods of time until a person ingests a large portion of food. This then blocks the esophagus – esophageal food bolus obstruction. It is also known as steakhouse syndrome named so because it often occurs when eating meat.
A mass in the neck and thoracic cavity, particularly the mediastinum, can press on the esophagus and cause a narrowing. The extrinsic compression may be due to :
- tumor (benign or malignant)
- enlarged heart (cardiomyopathy) particularly left atrium
- blood vessels – aortic aneurysm, subclavian artery (dysphagia lusoria)
- enlarged thyroid gland (goiter), thyroid mass (tumor, nodule, cyst)
Swelling of Esophagus
A swelling of the esophageal wall is a feature of inflammation (esophagitis). This is a common condition that arises for a number of reasons as outlined under types of esophagitis. Gastric acid reflux is among the more common causes of esophagitis (reflux esophagitis) these days and in chronic reflux, scarring can cause permanent obstruction. Eosinophilic esophagitis is an immune mediated process and can cause widespread inflammation throughout the entire length of the esophagus.
Nerve and Muscle Disorders
This includes a wide range of conditions like diffuse esophageal spasms, nutcracker esophagus, myasthenia gravis, Parkinson’s disease and multiple sclerosis. Here the peristaltic wave that pushes food down the esophagus is compromised. This may be due to a lack of coordination, weak muscle contractions or inappropriate relaxation of the gullet to allow food to travel through the esophagus. Spasms in addition cause a constriction of the esophagus.
Esophageal Webs and Rings
Esophageal webs are membranous projections from the inner lining of the esophagus (mucosa) that tend to occur in the upper parts of the esophagus. It is arranged in a semicircle manner. The exact cause is unknown but is often associated with chronic acid reflux (GERD). Esophageal rings, also known as Schatzki rings, are circular thickenings of the esophageal wall. It primarily involves the inner two layers of the esophagus (mucosa and submucosa) but can extend deeper.
Esophageal Mass and Wall Deformities
Esophageal tumors may protrude significantly into the lumen of the esophagus thereby causing a partial or complete obstruction. These tumors may be benign or malignant. Benign growths mainly comprise of leiomyomas and polyps while cancerous lesions include adenocarcinomas and squamous cell carcinomas. Outpouchings known as diverticulae (singular diverticula/diverticulum) may be some of the wall deformities that can lead to an obstruction. Zencker diverticulae occur higher up the esophagus while traction diverticulae occur lower down.