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(Cardiospasm; Esophageal Aperistalsis; Megaesophagus)
Achalasia is a disorder in which the rhythmic contractions of the esophagus are absent, the lower esophageal sphincter does not relax normally, and the resting pressure of the lower esophageal sphincter is increased.
Achalasia may occur at any age but usually begins, almost unnoticed, between the ages of 20 and 60 and then progresses gradually over many months or years.
Achalasia results from a malfunction of the nerves controlling the rhythmic contractions of the esophagus. The cause of the nerve malfunction is not known, but viral and autoimmune causes are suspected. Certain tumors may cause achalasia either by directly narrowing (constricting) the lower esophageal sphincter or by infiltrating the nerves of the esophagus. Chagas disease, which causes the destruction of clusters of nerve cells (autonomic ganglia), may also result in achalasia.
The tight lower esophageal sphincter causes the part of the esophagus above it to enlarge greatly. This enlargement contributes to many of the symptoms. Difficulty swallowing (dysphagia—see Difficulty Swallowing) both solids and liquids is the main symptom. Although less common, chest pain may occur during swallowing or for no apparent reason. About one third of people who have achalasia regurgitate undigested food while sleeping. They may inhale food into their lungs, which can cause coughing, a lung abscess, infection of the airways, bronchiectasis, or aspiration pneumonia. Undigested food typically remains in the esophagus. Mild to moderate weight loss also occurs. When people have significant weight loss, especially older people whose symptoms of dysphagia developed rapidly, doctors consider and look for a tumor at the gastroesophageal junction (the place where the esophagus connects to the stomach).
X-rays of the esophagus taken while the person is swallowing barium (a barium swallow—see X-Ray Studies) show an absence of the normal rhythmic waves of muscular contractions (peristalsis). The esophagus is widened, usually only moderately but occasionally to enormous proportions, but is narrow at the lower esophageal sphincter.
Doctors usually also insert a small tube into the esophagus to take pressure measurements of the contractions (esophageal manometry—see Manometry). Often, doctors examine the esophagus through a flexible viewing tube (esophagoscopy—see Endoscopy). During an esophagoscopy, the doctor performs a biopsy (removal of tissue samples for examination under a microscope) to make sure the symptoms are not caused by cancer at the lower end of the esophagus.
Achalasia that is caused by cancer at the gastroesophageal junction can be diagnosed by computed tomography (CT—see Computed Tomography and Magnetic Resonance Imaging) of the chest and abdomen or by an endoscopic ultrasound (a tiny ultrasound probe on the tip of an endoscope is passed through the mouth into the stomach—see Ultrasound Scanning (Ultrasonography)).
No treatment restores peristalsis. The aim of treatment is to relieve symptoms by decreasing pressure in the lower esophageal sphincter.
The first treatment is to dilate the sphincter mechanically by inflating a large balloon inside it. This procedure helps about 85% of the time, but repeated dilations may be needed. In fewer than 2% of people with achalasia, the esophagus ruptures during the dilation procedure. Esophageal rupture leads to severe inflammation in the chest outside the esophagus (mediastinitis) and, in rare cases, is fatal if not treated appropriately. Immediate surgery is needed to close the rupture in the wall of the esophagus.
Certain drugs can help relax the sphincter. They have limited effectiveness but may prolong the time between dilations. The most common drugs are nitrates (for example, isosorbide dinitrate placed under the tongue before meals) or calcium channel blockers (for example, nifedipine).
As an alternative to mechanical dilation, a doctor may inject botulinum toxin into the lower esophageal sphincter. This therapy is almost as effective as mechanical dilation with balloons, giving symptom relief for 70 to 80% of people, but the relief may last only 6 months to 1 year.
If dilation or botulinum toxin therapy does not work, a surgical procedure to cut the muscular fibers in the lower esophageal sphincter (called a myotomy) is usually done. The procedure is usually done with a laparoscope (see Laparoscopy) or, less commonly, with a thoracoscope (see Thoracoscopy). This procedure is successful about 85% of the time. After myotomy, about 15% to 30% of people have backflow of acid (gastroesophageal reflux—see Gastroesophageal Reflux (GERD)). A procedure to prevent backflow of acid from the stomach (called a fundoplication) is usually done at the same time as myotomy.
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