Swallowing disorders (also called dysphagia) are any conditions that cause impairment of the movement of solids or fluids from the mouth, down the throat, and into the stomach.
Swallowing disorders are a significant source of disability. They can have a severe effect on overall calorie intake and nutritional status, and they can adversely affect an individual's enjoyment of eating and drinking and the ability to participate in related social interactions. Swallowing disorders may affect the ability to swallow liquids, solids, or both. In addition to complicating or preventing intake of liquids and solids, some swallowing disorders may make an individual susceptible to pneumonia, if any portion of the substances being swallowed are directed into the lungs.
Many conditions are associated with swallowing disorders. Any condition that interferes with one or more of the three normal phases associated with swallowing will impair an individual's swallowing ability. The three normal phases include the oral phase, the pharyngeal phase, and the esophageal phase. Oral refers to the mouth; pharyngeal refers to the pharynx (the area of the airway at the back of the mouth, and leading to the esophagus and the lungs); esophageal refers to the esophagus (the tube passageway between the mouth and the stomach).
The oral phase refers to the aspects of swallowing that rely on intact mouth functioning. The oral phase is itself divided into two phases, the oral preparatory phase and the oral transit phase. In the oral preparatory phase, solids are broken into smaller, softer bits through chewing and mixing with saliva. The resulting mass to be swallowed is referred to as the "bolus." The oral transit phase refers to the movement of the bolus to the back of the mouth, through the actions of the tongue.
The pharyngeal phase refers to the transit of the bolus into the pharynx, also called the swallowing reflex. During this phase, it is crucial that breathing cease and that the entry from the pharynx into the larynx (voice box) closes tightly, thus preventing food or fluid from entering into the lungs.
The esophageal phase refers to the transit of the bolus down the esophagus and into the stomach. The esophageal phase is guided primarily by a series of involuntary waves of muscular action, called peristalsis, that move the bolus down the esophagus towards the stomach. At the end of the esophagus is an area called the esophageal sphincter, which must relax sufficiently to allow the bolus to enter the stomach. The esophageal sphincter, however, must also quickly resume appropriate muscle tone to avoid allowing stomach contents to exit the stomach and go back up the esophagus (called reflux).
Of the three phases of swallowing, only the oral phase requires conscious input; both the pharyngeal and the esophageal phases occur outside of voluntary control. The amount of time required for the oral phase varies depending on the individual; some people eat or drink very slowly, chewing many times, while others seem to "inhale" their food. Under normal conditions, the pharyngeal phase is over in about one second, and the esophageal phase takes about three seconds. Various disorders may increase the duration (and relative success) of any of these phases.
Swallowing disorders can be caused by the following:
- mechanical obstruction at any point along the swallowing path
- problems with the nerves and muscles necessary for chewing and moving the food around the mouth
- decreased sensation, leading to inability to feel the food and organize its movement appropriately
- inability of the larynx to close tightly
- problems with coordinating breathing and its cessation
- problems with the involuntary muscle movements necessary for moving the bolus down the esophagus
These problems may occur at the actual level of functioning (for example, muscle defects) or at the level of the brain's organization of these functions.
Complications of swallowing disorders include dehydration, weight loss, malnutrition, social isolation, and aspiration pneumonia.
Causes and symptoms
A huge variety of disorders may cause problems with swallowing, including:
- progressive neurological conditions (such as Parkinson's disease , multiple sclerosis , amyotrophic lateral sclerosis , Huntington's chorea , post-polio syndrome , myasthenia gravis , muscular dystrophy)
- mechanical blockage of the swallowing apparatus (by tumors; abnormal tissue growth called esophageal webs or rings; abnormal outpouchings of areas of the esopahagus called Zenker's diverticula; scar tissue or strictures due to radiation therapy, medications, toxic or chemical exposure, ulcers, or smoke inhalation)
- damage to the brain or spinal cord (due to cerebral palsy or after stroke , spinal cord injury , traumatic head injury, or direct injury to any of the structures necessary for swallowing)
- certain medications (nitrates, anticholinergic agents, aspirin, calcium tablets, calcium channel blockers, iron tablets, vitamin C, tetracycline)
- congenital defects (such as cleft palate)
Symptoms of swallowing difficulties include weight loss; dehydration; sensation of having a lump in the throat after having attempted to swallow; drooling; unintentional retention of food within the mouth, despite attempts to swallow; coughing; choking; change in voice; regurgitation of liquids or solids through the nose; difficulty chewing; difficulty breathing or talking while eating, drinking, and swallowing; recurrent bouts of pneumonia.
A variety of tests can diagnose dysphagia. A thorough neurological examination may reveal deficits involving the cranial nerves responsible for the strength and coordination of the muscles of swallowing. Fiberoptic endoscopy uses a narrow lighted scope to examine the mouth, pharynx, and esophagus. Videofluroscopic swallowing studies require the patient to swallow a solution containing barium; a moving x-ray machine takes images to evaluate the swallowing mechanism. Ultrasound studies can examine the tongue and larynx during swallowing. Scintigraphy involves swallowing a radioactive sub-stance, and then examining images to see if the patient is aspirating. Manometry is a test that measures the changes in pressure throughout the esophagus during swallowing, in order to evaluate peristalsis.
Neurologists, gastroenterologists, and otorhinolaryngologists may all work with patients suffering from dysphagia. Speech and language therapists are trained to evaluate and help individuals who have swallowing problems.
Treatment ranges from simple changes in posture while eating to medications to surgical interventions.
When swallowing problems are mild, learning new eating techniques (smaller bites, more chewing) may be sufficient. Therapists can help individuals learn the most effective head and neck posture for successful swallowing. Exercises to strengthen muscles necessary for swallowing and improve coordination may be helpful. In order to improve their ease of swallowing, some people learn to avoid foods with certain textures, to thin or thicken liquids, or to avoid foods or beverages that are too hot or too cold. Medications may help improve swallowing. Botulinum toxin can relax spastic muscle that interfere with swallowing.
When no therapies or medications are helpful, and an individual's nutritional status is seriously compromised, alternative methods of providing nutrition (such as through a feeding or gastrostomy tube directly into the stomach) may be necessary.
Dysphagia can be a very serious condition. Its prognosis depends on how severe the swallowing problems are and how severely they interfere with proper nutrition, as well as on details of the underlying condition responsible for the dysphagia.
Cohen, Disney, and Henry P. Parkman. "Diseases of the Esophagus." In Cecil Textbook of Internal Medicine, edited by Lee Goldman, et al. Philadelphia: W. B. Saunders Company, 2000.
Logemann, Jeri. "Mechanisms of Normal and Abnormal Swallowing." In Otolaryngology: Head and Neck Surgery, edited by Charles Cummings, et al. St. Louis: Mosby-Year Book, Inc., 1998.
Lind, C. D. "Dysphagia: Evaluation and Treatment." Gastroenterolgical Clinics of North America 32, no. 2 (June 2003): 553–575
American Academy of Otolaryngology—Head and Neck Surgery. Doctor, I Have Trouble Swallowing. 2002. <http://www.entnet.org/healthinfo/throat/swallowing.cfm> (June 3, 2004).
National Institute of Neurological Disorders and Stroke (NINDS). NINDS Swallowing Disorders Information Page. November 6, 2002. <http://www.ninds.nih.gov/health_and_medical/disorders/swallowing_disorders.htm> (June 3, 2004).
American Academy of Otolaryngology—Head and Neck Surgery. One Prince St., Alexandria, VA 22314-3357. 703-836-4444. <http://www.entnet.org/healthinfo/throat/swallowing.cfm>.
Rosalyn Carson-DeWitt, MD
Swallowing disorders include a number of diseases and conditions that cause difficulty in passing food or liquid from the mouth to the stomach.
Although normally swallowing is automatic, it is a complex process involving several phases and 29 muscles. Saliva helps soften food as it is chewed. The tongue helps move food to the back of the mouth, triggering a swallowing reflex that passes food through the pharynx. The epiglottis helps keep food from mistakenly going down the windpipe and into the esophagus, the canal that carries food to the stomach. Swallowing disorders can occur at any phase in the swallowing process. The medical term for difficult swallowing is dysphagia.
Each year, about 10 million people in the United States require medical evaluation for swallowing problems. Some experts say that about 10% of Americans develop symptoms of swallowing disorders in adulthood. Elderly people are the most likely to have problems with swallowing.
Causes and symptoms
Swallowing disorders often result from other conditions and diseases. For example, Parkinson's disease, cerebral palsy, stroke, head injury, and other central nervous system conditions can damage the muscles and nerves involved in swallowing. Some people are born with abnormalities in the swallowing structures, such as infants with cleft palate.
Some cancers can lead to swallowing disorders. Esophageal cancer can cause narrowing and eventual blockage of the esophagus. Surgery and radiation therapy for head and neck cancer can restrict or weaken tongue motion, paralyze vocal cords, or cause muscle damage that affects swallowing. An inflamed esophagus, often resulting from gastroesophageal reflux disease (GERD), can cause painful or difficult swallowing. Infections of the esophagus also can inflame it and cause it to narrow. Swallowing difficulty may result from aging, though researchers are not certain why.
The most common symptoms people report are choking and the feeling that food feels stuck in the throat. Other symptoms include needing to swallow many times to clear food from the mouth and throat, a gurgly, wet sound to the voice after swallowing, having to clear the throat after eating, coughing, pain while swallowing, bringing food back up (regurgitation), food or acid backing up into the throat, unexpected weight loss, and not being able to swallow at all. Children also may gag during meals and may have excessive drooling or leaking of food or liquid from their mouths during meals. They may have difficulty breathing when eating or drinking, spit up frequently and lag behind in weight gain. They also may have recurring pneumonia or respiratory infections.
A physician should perform a full head and neck examination based on the patient's symptoms. Speech-language pathologists may aid in the diagnosis. Physicians also might order a swallowing test to study how the patient swallows. The patient will be asked to drink a liquid with a contrast agent called barium that will show up on x rays of the throat and upper chest. The exam might be imaged with a technique called video fluoroscopy, which will take motion camera images in addition to still images. For this exam, the patient may be asked to swallow liquid, paste, and solids. A speech pathologist may work with the radiologist to perform this exam.
If the physician thinks the problem originates in the lower esophagus or has concerns about an abnormality in the esophagus, an endoscopy may be ordered. This test involves passing a thin, flexible instrument called an endoscope down the throat. The lighted endoscope helps the physician view the esophagus. Other tests may be used, including ultrasound.
Treatment will depend on the cause of the swallowing problem. Special exercises may help strengthen the muscles used for chewing and swallowing. Problems originating in the mouth may be treated with artificial saliva, improved hydration or better dental care. Esophageal problems will be treated depending on the cause. Patients with GERD will receive medications and instructions on how to better manage the disease. Esophageal cancer is a life-threatening disease that will involve coordinating care with an oncologist. Many patients will receive help with their disorders from speech pathologists. Special liquid diets may be ordered for patients who continue to have trouble chewing or swallowing. In severe cases, the patient may need a feeding tube that bypasses the part of the swallowing system that does not work.
Some herbs that may help improve swallowing include oil of peppermint and licorice. Valerian may be used as a tea. Homeopathic physicians may suggest some remedies aimed at improving bloating, indigestion, or cough. Alternative care should be sought from licensed practitioners and coordinated with physician care.
Cleft palate— An opening or hole in the roof of the mouth that occurs at birth when the roof fails to fully develop in the infant.
Epiglottis— A thin layer of cartilage behind the tongue that helps block food from entering the windpipe.
Pharynx— The muscular cavity that leads from the mouth and nasal passages to the larynx and esophagus.
In many cases, these disorders can be corrected. If not treated, swallowing disorders can lead to serious complications, including dehydration and malnutrition. There also is a risk of food entering the airway (aspiration) as a person attempts to swallow, which can lead to aspiration pneumonia as the food particles enter the lungs.
Many causes of swallowing disorders cannot be prevented. Slowly and fully chewing food helps. People with GERD should manage it to lower the risk of developing swallowing difficulties.
"Disorders of Swallowing." Harvard Men's Health Watch (Sept. 2003).
"The Evaluation and Management of Swallowing Disorders in the Elderly." Geriatric Times (Nov. 1, 2003): 17.
American Academy of Otolaryngology-Head and Neck Surgery. One Prince St., Alexandria, VA 22314-3357. 703-836-4444. http://www.entnet.org.
American Speech-Language Association (ASHA). 10801 Rockville Pike, Rockville, MD 20852. 800-638-8255. http://www.asha.org.
National Institute of Dental and Craniofacial Research (NIDCR). 45 Center Dr., Rm 4AS19 MSC 6400, Bethesda, MD 20892-6400. 301-496-4261. http://www.nidr.nih.gov.
NINDS Swallowing Disorders Information Page. Web page. National Institute of Neurological Disorders and Stroke, 2005. http://www.ninds.nih.gov/disorders/swallowing_disorders/swallowing_disorders.htm.