Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esophagus. Achalasia can happen at various points along the gastrointestinal tract; achalasia of the rectum, for instance, may occur in Hirschsprung's disease. The lower esophageal sphincter is a muscle between the esophagus and stomach that opens when food comes in. It closes to avoid stomach acids from coming back up. A fully understood cause to the disease is unknown, as are factors that increase the risk of its appearance. Suggestions of a genetically transmittable form of achalasia exist, but this is neither fully understood, nor agreed upon.
Esophageal achalasia is an esophageal motility disorder involving the smooth muscle layer of the esophagus and the lower esophageal sphincter (LES). It is characterized by incomplete LES relaxation, increased LES tone, and lack of peristalsis of the esophagus (inability of smooth muscle to move food down the esophagus) in the absence of other explanations like cancer or fibrosis.
Achalasia is characterized by difficulty in swallowing, regurgitation, and sometimes chest pain. Diagnosis is reached with esophageal manometry and barium swallow radiographic studies. Various treatments are available, although none cures the condition. Certain medications or Botox may be used in some cases, but more permanent relief is brought by esophageal dilatation and surgical cleaving of the muscle (Heller myotomy or POEM).
The most common form is primary achalasia, which has no known underlying cause. It is due to the failure of distal esophageal inhibitory neurons. However, a small proportion occurs secondary to other conditions, such as esophageal cancer, Chagas disease (an infectious disease common in South America) or Triple-A syndrome. Achalasia affects about one person in 100,000 per year. There is no gender predominance for the occurrence of disease. The term is from a- + -chalasia "no relaxation."
Achalasia can also manifest alongside other diseases as a rare syndrome such as achalasia microcephaly.
Signs and symptoms
The main symptoms of achalasia are dysphagia (difficulty in swallowing), regurgitation of undigested food, chest pain behind the sternum, and weight loss. Dysphagia tends to become progressively worse over time and to involve both fluids and solids. Some people may also experience coughing when lying in a horizontal position. The chest pain experienced, also known as cardiospasm and non-cardiac chest pain can often be mistaken for a heart attack. It can be extremely painful in some patients. Food and liquid, including saliva, are retained in the esophagus and may be inhaled into the lungs (aspiration). Untreated, mid-stage achalasia can fully obstruct the passage of almost any food or liquid – the greater surface area of the swallowed object often being more difficult to pass the LES/LOS (lower esophageal sphincter). At such a stage, upon swallowing food, it entirely remains in the esophagus, building up and stretching it to an extreme size in a phenomenon known as megaesophagus. If enough food builds up, it triggers a need to purge what was swallowed, often described as not being accompanied with nausea per se, but an intense and sometimes uncontrollable need to vomit what was built up in the esophagus that, due to the excessive stretching of the esophageal walls, is easily released without heaving. This cycle is so that little to practically no food reaches the small intestines to have its nutrients be absorbed into the bloodstream, leading to progressive weight loss, anorexia, eventual starvation, and death, the final of which may not always be listed as "death by achalasia", contributing to the already inaccurate or inconclusive count of deaths caused by the disease, not to mention the variable of other medical factors that could accelerate death of an achalasia patient's already weakened body.
Late-stage achalasia
End-stage achalasia, typified by a massively dilated and tortuous oesophagus, may occur in patients previously treated but where further dilatation or myotomy fails to relieve dysphagia or prevent nutritional deterioration, and esophagectomy may be the only option.
End stage disease, characterised by a markedly dilated and tortuous "burned-out" esophagus and recurrent obstructive symptoms, may require oesophageal resection in order to restore gastro-intestinal function, reverse nutritional deficits and reduce the risk of aspiration pneumonia.