Merck Manual

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(Cardiospasm; Esophageal Aperistalsis; Megaesophagus)


Kristle Lee Lynch

, MD, Perelman School of Medicine at The University of Pennsylvania

Reviewed/Revised Feb 2024
Topic Resources

Achalasia is a disorder in which the rhythmic contractions of the esophagus (called peristalsis) are missing or impaired, the lower esophageal sphincter does not relax normally, and the resting pressure of the lower esophageal sphincter is increased.

  • This cause of this disorder usually is not known, but it may occur after exposure to some viruses.

  • The main symptoms of achalasia are trouble swallowing, spitting up of liquid and food, chest pain, and weight loss.

  • The diagnosis is based on results of manometry and barium swallow x-rays.

  • Treatment is aimed at relieving symptoms by dilating the lower esophageal sphincter with a balloon or cutting the muscle fibers of the sphincter, and sometimes by injecting botulinum toxin.

The esophagus Throat and Esophagus The throat (pharynx) lies behind and below the mouth. When food and fluids leave the mouth, they pass through the throat. Swallowing of food and fluids begins voluntarily and continues automatically... read more is the hollow tube that leads from the throat (pharynx) to the stomach. (See also Overview of the Esophagus Overview of the Esophagus The esophagus is the hollow tube that leads from the throat (pharynx) to the stomach. Food does not just fall through the esophagus into the stomach. The walls of the esophagus propel food to... read more .) The lower esophageal sphincter is the ring of muscle that holds the bottom of the esophagus closed so that food and stomach acid do not flow back up the esophagus. When people swallow, this sphincter normally relaxes to allow food into the stomach.

How the Esophagus Works

As a person swallows, food moves from the mouth to the throat, also called the pharynx (1). The upper esophageal sphincter opens (2) so that food can enter the esophagus, where waves of muscular contractions, called peristalsis, propel the food downward (3). The food then passes through the diaphragm (4) and lower esophageal sphincter (5) and moves into the stomach.

How the Esophagus Works

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.

Causes of Achalasia

Achalasia results from a malfunction of the nerves (called denervation) controlling the rhythmic contractions of the esophagus. The cause of the denervation is not usually known, but viral and autoimmune causes are suspected. Certain tumors may cause an achalasia–like disorder either by directly narrowing (constricting) the lower esophageal sphincter or by infiltrating the nerves of the esophagus. Chagas disease Chagas Disease Chagas disease is an infection caused by the protozoa Trypanosoma cruzi, which is transmitted by the bite of a kissing bug (also called an assassin or Triatominae bug). The protozoa ... read more Chagas Disease , an infection that causes the destruction of clusters of nerve cells (autonomic ganglia), may also result in achalasia.

Symptoms of 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 Difficulty Swallowing Some people have difficulty swallowing (dysphagia). In dysphagia, foods and/or liquids do not move normally from the throat (pharynx) to the stomach. People feel as though food or liquids become... read more (dysphagia) of both solids and liquids is the main symptom. Although less common, chest pain Chest or Back Pain Pain in the middle of the chest or upper back can result from disorders of the esophagus or from disorders of the heart or aorta ( see Chest Pain). Symptoms may be similar. Gastroesophageal... read more may occur during swallowing or for no apparent reason. About one third of people who have achalasia spit up (regurgitate Regurgitation and Rumination Regurgitation is the spitting up of food from the esophagus or stomach without nausea or forceful contractions of the abdominal muscles. Rumination is regurgitation with no apparent physical... read more ) liquids and undigested food. If spitting up occurs when people are sleeping, they may inhale food into their lungs, which can cause coughing, infection of the airways, bronchiectasis Bronchiectasis Bronchiectasis is an irreversible widening (dilation) of portions of the breathing tubes or airways (bronchi) resulting from damage to the airway wall. The most common cause is severe or repeated... read more , or aspiration pneumonia Aspiration Pneumonia and Chemical Pneumonitis Aspiration pneumonia is lung infection caused by inhaling mouth secretions, stomach contents, or both. Chemical pneumonitis is lung irritation caused by inhalation of substances irritating or... read more .

Mild to moderate weight loss also occurs. When people have significant weight loss, especially older adults whose symptoms of dysphagia developed rapidly, doctors consider and usually look for a tumor at the gastroesophageal junction (the place where the esophagus connects to the stomach).

Diagnosis of Achalasia

  • Manometry

  • Barium swallow x-rays

Doctors usually insert a small tube into the esophagus to take pressure measurements of the esophagus and lower esophageal sphincter (esophageal manometry Manometry Manometry is measurement of pressure within various parts of the digestive tract. People must not eat or drink anything after midnight before the test. In this test, a flexible tube with pressure... read more ). Often, doctors examine the esophagus through a flexible viewing tube (esophagoscopy Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). In addition to examinations, doctors can use endoscopy to do biopsies and give treatment. Endoscopes... read more ). During an esophagoscopy, the doctor may do 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.

X-rays of the esophagus taken while the person is swallowing barium (a barium swallow X-Ray Studies of the Digestive Tract X-rays often are used to evaluate digestive problems. Standard x-rays ( plain x-rays) can show some blockages or paralysis of the digestive tract, or abnormal air patterns in the abdominal cavity... read more ) show the normal rhythmic contractions of the esophagus are missing. The esophagus is widened, usually only moderately but occasionally to enormous proportions, but is narrow at the lower esophageal sphincter.

Impedance planimetry Impedance Testing Impedance testing is a type of test that uses a probe that inflates a balloon inside the esophagus and measures how much pressure it takes to expand it a certain amount. An esophagus that is... read more is a type of esophageal test. In this test, a balloon filled with salt water (saline solution) is used to measure the area across the inside of the esophagus (called the lumen) and the pressure inside of the esophagus at the same time. A functional lumen imaging probe (FLIP) is another esophageal test that uses impedance planimetry to evaluate how the esophagus functions. These measurements help doctors further evaluate people who are having trouble swallowing.

Some disorders, such as cancer at the gastroesophageal junction, can cause symptoms similar to achalasia (called pseudoachalasia), so doctors may do additional tests to rule them out. Cancer at the gastroesophageal junction can be diagnosed by esophagoscopy, computed tomography Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT) and magnetic resonance imaging (MRI) scans are good tests for assessing the size and location of abdominal organs. Additionally, cancerous (malignant) or noncancerous... read more (CT) of the chest and abdomen, or by endoscopic ultrasonography Ultrasound Scanning (Ultrasonography) of the Abdomen Ultrasound scanning uses sound waves to produce pictures of internal organs (see also Ultrasonography). An ultrasound scan can show the size and shape of many organs, such as the liver and pancreas... read more Ultrasound Scanning (Ultrasonography) of the Abdomen (an ultrasound probe on the tip of an endoscope is passed through the mouth into the stomach).

Treatment of Achalasia

  • Balloon dilation

  • Myotomy

  • Sometimes botulinum toxin injections

No treatment restores peristalsis of the esophagus. The aim of treatment is to relieve symptoms by decreasing pressure in the lower esophageal sphincter.

There are two main treatment options for relieving the symptoms of achalasia that are equally effective and have similar outcomes.

Balloon dilation involves dilating the sphincter mechanically by inflating a large balloon inside it. This procedure is often successful, but repeated dilations may be needed. There is a small risk of the esophagus rupturing during the dilation procedure. Esophageal rupture leads to severe inflammation in the chest outside the esophagus (mediastinitis Mediastinitis Mediastinitis is inflammation of the mediastinum (the chest cavity, which contains the heart, the thymus gland, some lymph nodes, and parts of the esophagus, aorta, thyroid, and parathyroid... read more ) and, in rare cases, is fatal if not treated appropriately. Immediate surgery is needed to close the rupture in the wall of the esophagus.

After myotomy, some people have an increased risk of developing a backflow of acid into the esophagus (gastroesophageal reflux disease Gastroesophageal Reflux Disease (GERD) In gastroesophageal reflux disease, stomach contents, including acid and bile, flow backward from the stomach into the esophagus, causing inflammation in the esophagus and pain in the bottom... read more Gastroesophageal Reflux Disease (GERD) ). A procedure to prevent backflow of acid from the stomach (called a fundoplication) is usually done at the same time as myotomy.

Botulinum toxin can temporarily paralyze muscles, thus doctors sometimes inject botulinum toxin into the lower esophageal sphincter to relax it. This injection is an alternative to balloon dilation or myotomy and is almost as effective. However, the results typically last for only 6 months to 1 year, which is shorter than other treatments last.

Certain medications, such as nitrates or calcium channel blockers, have been studied but have not proved to be effective.

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