How do we swallow?
Swallowing is a complex process. Some 50 pairs of muscles and many nerves work to move food from the mouth to the stomach. This happens in three stages. First, the tongue moves the food around in the mouth for chewing. Chewing makes the food the right size to swallow and helps mix the food with saliva. Saliva softens and moistens the food to make swallowing easier. During this first stage, the tongue collects the prepared food or liquid, making it ready for swallowing.
The second stage begins when the tongue pushes the food or liquid to the back of the mouth, which triggers a swallowing reflex that passes the food through the pharynx (the canal that connects the mouth with the esophagus). During this stage, the larynx (voice box) closes tightly and breathing stops to prevent food or liquid from entering the lungs.
The third stage begins when food or liquid enters the esophagus, the canal that carries food and liquid to the stomach. This passage through the esophagus usually occurs in about 3 seconds, depending on the texture or consistency of the food.
How does dysphagia occur?
Dysphagia occurs when there is a problem with any part of the swallowing process. Weak tongue or cheek muscles may make it hard to move food around in the mouth for chewing. Food pieces that are too large for swallowing may enter the throat and block the passage of air.
Other problems include not being able to start the swallowing reflex (a stimulus that allows food and liquids to move safely through the pharynx) because of a stroke or other nervous system disorder. People with these kinds of problems are unable to begin the muscle movements that allow food to move from the mouth to the stomach. Another difficulty can occur when weak throat muscles cannot move all of the food toward the stomach. Bits of food can fall or be pulled into the windpipe (trachea), which may result in lung infection.
What are some problems caused by dysphagia?
Dysphagia can be serious. Someone who cannot swallow well may not be able to eat enough of the right foods to stay healthy or maintain an ideal weight.
Sometimes, when foods or liquids enter the windpipe of a person who has dysphagia, coughing or throat clearing cannot remove it. Food or liquid that stays in the windpipe may enter the lungs and create a chance for harmful bacteria to grow. A serious infection (aspiration pneumonia) can result.
Swallowing disorders may also include the development of a pocket outside the esophagus caused by weakness in the esophageal wall. This abnormal pocket traps some food being swallowed. While lying down or sleeping, a person with this problem may draw undigested food into the pharynx. The esophagus may be too narrow, causing food to stick. This food may prevent other food or even liquids from entering the stomach.
What causes dysphagia?
Dysphagia has many causes. Any condition that weakens or damages the muscles and nerves used for swallowing may cause dysphagia. For example, people with diseases of the nervous system, such as cerebral palsy or Parkinson’s disease, often have problems swallowing. Additionally, stroke or head injury may affect the coordination of the swallowing muscles or limit sensation in the mouth and throat. An infection or irritation can cause narrowing of the esophagus. People born with abnormalities of the swallowing mechanism may not be able to swallow normally. Infants who are born with a hole in the roof of the mouth (cleft palate) are unable to suck properly, which complicates nursing and drinking from a regular baby bottle.
In addition, cancer of the head, neck, or esophagus may cause swallowing problems. Sometimes the treatment for these types of cancers can cause dysphagia. Injuries of the head, neck, and chest may also create swallowing problems.
How is dysphagia treated?
There are different treatments for various types of dysphagia. First, doctors and speech-language pathologists who test for and treat swallowing disorders use a variety of tests that allow them to look at the parts of the swallowing mechanism. One test, called a fiber optic laryngoscopy, allows the doctor to look down the throat with a lighted tube. Other tests, including video fluoroscopy, which takes videotapes of a patient swallowing, and ultrasound, which produces images of internal body organs, can painlessly take pictures of various stages of swallowing.
Once the cause of the dysphagia is found, surgery or medication may help. If treating the cause of the dysphagia does not help, the doctor may have the patient see a speech-language pathologist who is trained in testing and treating swallowing disorders. The speech-language pathologist will test the person’s ability to eat and drink and may teach the person new ways to swallow.
Treatment may involve muscle exercises to strengthen weak facial muscles or to improve coordination. For others, treatment may involve learning to eat in a special way. For example, some people may have to eat with their head turned to one side or looking straight ahead. Preparing food in a certain way or avoiding certain foods may help other people. For instance, those who cannot swallow liquids may need to add special thickeners to their drinks. Other people may have to avoid hot or cold foods or drinks.
For some, however, consuming foods and liquids by mouth may no longer be possible. These individuals must use other methods to nourish their bodies. Usually this involves a feeding system, such as a feeding tube, that bypasses the part of the swallowing mechanism that is not working normally.