How is dysphagia evaluated and the cause diagnosed?
The history from an individual with dysphagia often provides important clues to the underlying cause of the dysphagia.
The nature of the symptom or symptoms provides the most important clues to the cause of dysphagia. Swallowing that is difficult to initiate or that leads to nasal regurgitation, cough, or choking is most likely due to an oral or pharyngeal problem. Swallowing that results in the sensation of food sticking in the chest (esophagus) is most likely due to an esophageal problem.
Dysphagia that progresses rapidly over weeks or a few months suggests a malignant tumor. Dysphagia for solid food alone suggests a physical obstruction to the passage of food, whereas dysphagia for both solid and liquid food is more likely to be caused by a disease of the smooth muscle of the esophagus. Intermittent symptoms also are more likely to be caused by diseases of smooth muscle than obstruction of the esophagus since dysfunction of the muscle often is intermittent.
Preexisting diseases also provide clues. Those with diseases of skeletal muscle (for example, polymyositis), the brain (most commonly stroke), or the nervous system are more likely to have dysphagia on the basis of dysfunction of the oropharyngeal muscles and nerves. People with collagen vascular diseases, for example, scleroderma, are more likely to have problems with the esophageal muscles, especially ineffective peristalsis.
Patients with a history of GERD are more likely to have esophageal strictures as the cause of their dysphagia, though about 20% of patients with strictures have minimal or no symptoms of GERD before the onset of dysphagia. It is believed that reflux that occurs at night is more injurious to the esophagus. There also is a higher risk of esophageal cancer among individuals with long-standing GERD.
Loss of weight can be a sign of either severe dysphagia or a malignant tumor. More often than losing weight, people describe a change in their eating pattern—smaller bites, additional chewing—that prolongs meals so that they are the last one at the table to finish eating. This latter pattern, if present for a prolonged period of time, suggests a non-malignant, relatively stable or slowly progressive cause for the dysphagia. Episodes of chest pain that are not due to heart disease suggest muscular diseases of the esophagus. Birth and residence in Central or South America is associated with Chagas disease.
The physical examination is of limited value in suggesting causes for dysphagia. Abnormalities of the neurological examination suggest neurologic or muscle diseases. By observing an individual swallowing, one can determine if there is difficulty in initiating swallows, a sign of neurological disease. Tumors in the neck suggest the possibility of compression of the pharynx. A trachea that cannot be moved from side to side with the hand suggests a tumor lower down in the chest that has entrapped the trachea and possibly the esophagus. Observing atrophy (reduced size) or fasiculations of the tongue (fine tremors) also suggest diseases of the nervous system or skeletal muscle.
Endoscopy. Endoscopy involves the insertion of a long (one meter), flexible tube with a light and camera on its end through the mouth, pharynx, esophagus, and into the stomach. The lining of the pharynx and esophagus can be evaluated visually, and biopsies (small pieces of tissue) can be obtained for examination under the microscope or for bacterial or viral cultures.
Endoscopy is an excellent means of diagnosing tumors, strictures, and Schatzki's rings as well as infections of the esophagus. It also is very good for diagnosing diverticuli of the middle and lower esophagus but poor for diagnosing diverticuli in the upper esophagus (Zenker's diverticulum).
It is possible to observe abnormalities of esophageal muscular contraction, but esophageal manometry is a test that is much better suited for evaluating function of the esophageal muscles. Resistance passing the endoscope through the lower esophageal sphincter combined with a lack of esophageal contractions is a fairly reliable sign of achalasia or Chagas disease (due to the inability of the lower esophageal sphincter to relax), but it is important when there is resistance to exclude the presence of a stricture or cancer which also can cause resistance. Finally, there is a characteristic appearance of the esophageal lining when infiltrated with eosinophils that strongly suggests the presence of eosinophilic esophagitis.
X-rays. There are two different types of X-rays that can be done to diagnose the cause of dysphagia. The barium swallow or esophagram is the simplest type. For the barium swallow, mouthfuls of barium are swallowed, and X-ray films are taken of the esophagus at several points in time while the bolus of barium traverses the esophagus. The barium swallow is excellent for diagnosing moderate-to-severe external compression, tumors, and strictures of the esophagus. Occasionally, however, Schatzki's rings can be missed.
Another type of X-ray study that can be done to evaluate swallowing is the video esophagram or video swallow, sometimes called a video-fluoroscopic swallowing study. For the video swallow, instead of several static X-ray images of the bolus traversing the esophagus, a video X-ray is taken. The video study can be reviewed frame by frame and is able to show much more than the barium swallow. This usually is not important for diagnosing tumors or strictures, which are well seen on barium swallow, but it is more effective for suggesting problems with the contraction of the muscles of the esophagus and pharynx (though esophageal manometry, discussed later, is still better for studying contraction), milder external compression of the esophagus, and Schatzki's rings. The video study can be extended to include the pharynx where it is the best method for demonstrating osteophytes, cricopharyngeal bars, and Zenker's diverticuli. A modified barium swallow is a version of the test evaluating the oropharyngeal phases of swallowing. A speech pathologist is usually involved with the evaluation to determine subtle sequence and phase abnormalities.
The video swallow also is excellent for diagnosing penetration of barium (the equivalent of food) into the larynx and trachea due to neurological and muscular problems of the pharynx that may be causing coughing or choking after swallowing food.
Esophageal manometry. Esophageal manometry, also known as esophageal motility testing, is a means to evaluate the function of pharyngeal and esophageal muscles. For manometry, a thin, flexible catheter is passed through the nose and pharynx and into the esophagus. The catheter is able to sense pressure at multiple locations along its length in both the pharynx and the esophagus. When the pharyngeal and esophageal muscles contract, they generate a pressure on the catheter which is sensed, measured and recorded from each location. The magnitude of the pressure at each pressure-sensing location and the timing of the increases in pressure at each location in relation to other locations give an accurate picture of how the muscles of the pharynx and esophagus are contracting.
The value of manometry is in diagnosing and differentiating among diseases of the muscle or the nerves controlling the muscles that result in muscle dysfunction of the pharynx and esophagus. Thus, it is useful for diagnosing the swallowing dysfunction caused by diseases of the brain, skeletal muscle of the pharynx, and smooth muscle of the esophagus.
Esophageal impedence. Esophageal impedence testing utilizes catheters similar to those used for esophageal manometry. Impedence testing, however, senses the flow of the bolus through the esophagus. Thus, it is possible to determine how well the bolus is traversing the esophagus and correlate the movement with concomitantly recorded esophageal pressures determined by manometry. (It also can be used to sense reflux of stomach contents into the esophagus among patients with GERD.) Multiple sites along the length of the esophagus can be tested to assess the movement of the bolus and presence of reflux, including how high up it extends.
Esophageal acid testing. Esophageal acid testing is not a test that directly diagnoses diseases of the esophagus. Rather, it is a method for determining whether or not there is reflux of acid from the stomach into the esophagus, a cause of the most common esophageal problem leading to dysphagia, esophageal stricture. For acid testing, a thin catheter is inserted through the nose, down the throat, and into the esophagus. At the tip of the catheter and placed just above the junction of the esophagus with the stomach is an acid-sensing probe. The catheter coming out of the nose passes back over the ear and down to the waist where it is attached to a recorder. Each time acid refluxes (regurgitates) from the stomach and into the esophagus it hits the probe, and the reflux of acid is recorded by the recorder. At the end of a prolonged period, usually 24 hours, the catheter is removed and the information from the recorder is downloaded into a computer for analysis. Most people have a small amount of reflux of acid, but individuals with GERD have more. Thus, acid testing can determine if GERD is likely to be the cause of the esophageal problem such as a stricture, as well as if treatment of GERD is adequate by showing the amount of acid that refluxes during treatment is normal.
An alternative method of esophageal acid testing uses a small capsule containing an acid-sensing probe that is attached to the esophageal lining just above the junction of the esophagus with the stomach. The capsule wirelessly transmits the presence of episodes of acid regurgitation to a receiver carried on the chest. The capsule records for two or three days and later is shed into the esophagus and passes out of the body in the stool.
Other tests.The diagnosis of muscular dystrophies and metabolic myopathies usually involves a combination of tests including blood tests that can suggest muscle injury, electromyograms to determine if nerves and muscles are working normally, biopsies of muscles, and genetic testing.