Swallowing of food and water consists of two phases. In the first phase, the food is chewed in the mouth with the help of teeth and muscles of the mouth and tongue, and is converted into a bolus; this bolus is then pushed towards the throat or the pharynx. Once the food bolus reaches the pharynx, it stimulates nerves, which carry the signal to the brain. The brain sends back signals to initiate the swallowing reflex. The epiglottis closes the airway and the food moves down the esophagus or food pipe, aided by the coordinated contractions of various muscles. The lower esophageal sphincter (the muscular guard at the lower end of the esophagus) relaxes to allow the food to enter the stomach. Thus, the swallowing process involves a coordinated effort of muscles, nerves and the brain. A problem at any of these levels could result in dysphagia.
The problem can be located based on the symptoms that the patient complains. For example,
► If the patient complains of chocking or coughing while trying to swallow, the problem is likely to be located in the mouth or pharynx.
► If the patient complains of a feeling of food sticking in the throat or chest, the problem may be lower down in the food pipe.
► A problem with swallowing only solids is likely due to a physical obstruction like a tumor. Cancer causes rapidly progressive dysphagia.
► A difficulty with swallowing for solids as well as liquids that worsens progressively and may be associated with pain may be due to a neuromuscular problem.
A simple examination of the mouth may be enough if the cause of dysphagia is in the mouth. If the cause is located deeper below in the food pipe, swallowing tests may be necessary. Some of the swallowing tests used include barium swallow studies, Flexible Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST) and videofluoroscopic swallow study (VFSS). Endoscopy may be necessary to study the inner lining of the esophagus for any damage or obstruction.
Some conditions like cleft lip and cleft palate can cause dysphagia in children. Medications like antihistamines tend to dry up the mouth and make it difficult to swallow. Other causes of dysphagia are listed below:
Diseases that cause problems with muscles, nerves or neuromuscular coordination: Conditions that affect the coordination between the muscles of the esophagus and the nervous system can result in dysphagia. These conditions include:
► Achalasia: Achalasia cardia is a condition where the lower end of the esophagus does not relax properly, thus preventing the emptying of food into the stomach. The patient complains of regurgitation of undigested food particles. The condition tends to worsen with time if left untreated.
► Spasm of the Esophagus: Spasm of the esophageal muscles obstructs the passage of food to the stomach. The cause of spasm is often not known, but could be triggered by very hot or very cold foods, anxiety or acid reflux. The patient may complain of pain in the chest or upper abdomen.
► Scleroderma: Scleroderma is a condition where there is thickening of the esophageal tissues. The patient may complain of heartburn, due to regurgitation of acid into the lower end of the esophagus.
► Myopathies: Myopathies refer to diseases affecting muscles. Myopathies like polymyositis, dermatomyositis and muscular dystrophy can affect the muscles of the esophagus and result in difficulty with swallowing. The patient may complain of general weakness as well.
► Eosinophilic Eesophagitis: Eosinophilic esophagitis is a condition that is sometimes seen in patients with food allergy. The esophagus is infiltrated by allergy cells called eosinophils. The patient may complain of difficulty with swallowing, heartburn, and a feeling of food getting stuck in the throat. The condition may improve if the food that causes the allergy is eliminated from the diet.
► Conditions Affecting Nerves: Conditions affecting nerves that supply to the esophagus could result in difficulty in swallowing. These conditions include peripheral neuropathy and myasthenia gravis. In addition, conditions like multiple sclerosis and Huntingtonís disease can also result in dysphagia. These conditions are also associated with generalized weakness as well.
► Conditions Affecting the Brain: Conditions like stroke, brain tumors and Parkinsonís disease can sometimes affect swallowing.
Obstruction within the mouth, pharynx, or esophagus: Conditions that physically obstruct the passage of food through the upper digestive tract result in dysphagia. These include:
► Tumors: Tumors of the upper digestive tract can interfere with the swallowing process. The tumors in the mouth and throat may be obvious on examination. However, tumors deeper down in the food pipe may need to be examined with the help of an endoscope. These tumors cause dysphagia that progressively worsens. The patient is often elderly, who shows a distinct loss of weight.
► Strictures: Strictures are tight areas that are formed when the muscle tissue is replaced by fibrous tissue, which is inelastic. Strictures are usually a consequence of some damage to the muscle. Common causes of strictures are excess acidity which may cause ulcers that heal with scarring, radiation, or intake of certain medications or chemicals. The patient may complain of pain along with dysphagia in some of these cases. Medications like antibiotics and nonsteroidal anti-inflammatory agents are commonly associated with direct damage to the inner lining of the esophagus. Medications like nitrates and foods that include alcohol, fat and chocolate reduce the tone of the lower esophageal sphincter and result in reflux, thereby damaging the esophagus.
► Lower Esophageal Rings and Webs: Esophageal rings and webs are structural abnormalities that are sometimes present since birth. Though they usually do not cause any symptoms, in some cases they may obstruct the movement of food into the stomach and contribute to dysphagia.
► Foreign Body: A foreign body may be a large piece of food or any other object that may cause sudden obstruction to the passage of food. This problem is often seen in children.
► Zenker Diverticulum: Zenker diverticulum is a small pouch that develops at a weak point in the lower pharynx (throat) into which the food particles may enter. Though this condition is often asymptomatic and does not cause obstruction per se, in some cases, it may cause dysphagia, a feeling of a lump in the neck, regurgitation of food into the mouth and cough. The patient often suffers from bad breath.
Compression of the esophagus from outside: Structures around the esophagus like blood vessels or lymph nodes may enlarge and put pressure from outside, thus resulting in dysphagia.
► Compression from a Blood Vessel: Compression of the esophagus may occur due to an enlarged heart or aorta (the largest artery of the body). In addition, any aberrant vessels may also compress the esophagus from outside.
► Other Causes: Other causes of compression could be enlarged lymph nodes or thyroid gland. Spondylosis of the spine in the neck could also contribute to swallowing difficulties. These conditions may be detected through radiological tests.
Frequently Asked Questions (FAQs)
1. Which doctor should I visit in case I suffer from dysphagia?
You may contact your general physician, a general surgeon or gastroenterologist if you suffer from difficulty with swallowing.
2. What are the possible consequences of dysphagia?
Dysphagia could result in a general neglect to eat food, thereby leading to malnutrition. In addition, the food contents could regurgitate up to the mouth and from there, get aspirated into the lungs, resulting in pneumonia.