Achalasia (cont.)
How is achalasia diagnosed?
The diagnosis of achalasia often is suspected on the
basis of the history. Patients usually describe a progressive (worsening) of 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 will 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 occurs with both solid and liquid food, whereas in
esophageal stricture and cancer, the dysphagia typically occurs only with solid
food.
X-ray studies
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.
Esophageal manometry
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. 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
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.
Two conditions can mimic achalasia, esophageal cancer and Chagas' disease 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.
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 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.
Next: How is achalasia treated? »
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