Achalasia

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. 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. 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). 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. 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 sufferers. Food and liquid, including saliva, are retained in the esophagus and may be inhaled into the lungs (aspiration). The cause of most cases of achalasia is unknown. LES pressure and relaxation are regulated by excitatory (e.g., acetylcholine, substance P) and inhibitory (e.g., nitric oxide, vasoactive intestinal peptide) neurotransmitters. People with achalasia lack noradrenergic, noncholinergic, inhibitory ganglion cells, causing an imbalance in excitatory and inhibitory neurotransmission. The result is a hypertensive nonrelaxed esophageal sphincter. Autopsy and myotomy specimens have, on histological examination, shown an inflammatory response consisting of CD3/CD8-positive cytotoxic T lymphocytes, variable numbers of eosinophils and mast cells, loss of ganglion cells, and neurofibrosis; these events appear to occur early in achalasia. Thus, it seems there is an autoimmune context to achalasia, most likely caused by viral triggers. Other studies suggest hereditary, neurodegenerative, genetic and infective contributions. Due to the similarity of symptoms, achalasia can be mistaken for more common disorders such as gastroesophageal reflux disease (GERD), hiatus hernia, and even psychosomatic disorders.Specific tests for achalasia are barium swallow and esophageal manometry. In addition, endoscopy of the esophagus, stomach, and duodenum (esophagogastroduodenoscopy or EGD), with or without endoscopic ultrasound, is typically performed to rule out the possibility of cancer. The internal tissue of the esophagus generally appears normal in endoscopy, although a 'pop' may be observed as the scope is passed through the non-relaxing lower esophageal sphincter with some difficulty, and food debris may be found above the LES.