What tests do doctors use to diagnose achalasia?
The diagnosis of achalasia often is suspected on the basis of the history. Patients usually describe a progressive (worsening) of swallowing (dysphagia) for solid and liquid food over a period of many months to years. They may note regurgitation of food, chest pain, or loss of weight. Rarely, the first symptom is aspiration pneumonia.
Because patients typically learn to compensate for their dysphagia by taking smaller bites, chewing well, and eating slowly, the diagnosis of achalasia often is delayed by months or even years. The delay in diagnosis of achalasia is unfortunate because it is believed that early treatment -- before marked dilation of the esophagus occurs
-- can prevent esophageal dilation and its complications.
The dysphagia in achalasia also is different from the dysphagia of esophageal stricture (narrowing of the esophagus due to scarring) and esophageal cancer. In achalasia, dysphagia usually occurs with both solid and liquid food, whereas in esophageal stricture and cancer, the dysphagia typically occurs only with solid food and not liquids, until very late in the progression of the stricture. The progressive worsening of the dysphagia, especially with cancer, is more rapid.
The diagnosis of achalasia usually is made by an X-ray study called a video-esophagram in which video X-rays of the esophagus are taken after barium is swallowed. The barium fills the esophagus, and the emptying of the barium into the stomach can be observed. In achalasia, the video-esophagram shows that the esophagus is dilated (enlarged or widened), with a characteristic tapered narrowing of the lower end, sometimes likened to a "bird's beak." In addition, the barium stays in the esophagus longer than normal before passing into the stomach.
Another test, esophageal manometry, can demonstrate specifically the abnormalities of muscle function that are characteristic of achalasia, that is, the failure of the muscle of the esophageal body to contract with swallowing and the failure of the lower esophageal sphincter to relax. For manometry, a thin tube that measures the pressure generated by the contracting esophageal muscle is passed through the nose, down the back of the throat and into the esophagus. In a patient with achalasia, no peristaltic waves are seen in the lower half of the esophagus after swallows, and the pressure within the contracted lower esophageal sphincter does not fall with the swallow. In patients with vigorous achalasia, a strong simultaneous contraction of the muscle may be seen in the lower esophageal body. An advantage of manometry is that it can diagnose achalasia early in its course at a time at which the video-esophagram may be normal.
Endoscopy also is helpful in the diagnosis of achalasia although it can be normal early in achalasia. Endoscopy is a procedure in which a flexible fiberoptic tube with a light and camera on the end is swallowed. The camera provides direct visualization of the inside of the esophagus. One of the earliest endoscopic findings in achalasia is resistance as the endoscope is passed from the esophagus and into the stomach due to the high pressure in the lower esophageal sphincter. Later, endoscopy may reveal a dilated esophagus and a lack of peristaltic waves. Endoscopy also is important because it excludes the presence of esophageal cancer and other causes of dysphagia.
Two conditions can mimic achalasia, esophageal cancer and Chagas' disease (Chagas) of the esophagus. Both can give rise to video-esophageal and manometric abnormalities that are indistinguishable from achalasia. Fortunately, endoscopy usually can exclude the presence of cancer. If there is more concern, computerized tomography (CT) or magnetic resonance imaging (MRI) of the lowermost esophagus can be done to identify cancers near the lower esophageal sphincter.
Chagas' disease is an infection caused by the parasite, Trypanosoma cruzi, and is limited to Central and South America. It is passed to humans through insect bites from the reduviid bug. The parasite is shed in the bug's feces at the time it is biting. Scratching the bite breaks the skin and allows the parasite to enter the body. The parasite spreads throughout the body but takes up primary residency in the muscles of the gastrointestinal tract, from the esophagus to the rectum, though it also often affects the muscle of the heart. In the gastrointestinal tract, the parasite causes degeneration of the nerves controlling the muscles and can lead to abnormal function anywhere in the gastrointestinal tract. When it affects the esophagus, the abnormalities are identical to those of achalasia.
Acute Chagas' disease occurs mostly in children. In those individuals who are seen at a much later time for problems of swallowing, the acute illness is long-gone. The diagnosis of Chagas' disease can be suspected if there is involvement of other parts of the gastrointestinal tract, such as dilation of the small intestine or the colon, and the heart. The best method for making a diagnosis is by serological tests looking for antibodies in the blood against the parasite.