Esophageal 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. 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. It is characterized by incomplete LES relaxation, increased LES tone, and lack of peristalsis of the esophagus in the absence of other explanations like cancer or fibrosis. Conversely, achalasia can provoke other diseases; in particular, esophageal cancer is an important concern. The impaired transmission of food may cause candidiasis in the esophagus, which in turn is a risk factor for cancer.
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.
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 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, 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.
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. 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.
A review of the literature shows similar results with good symptom control reported in 75–100% of patients undergoing such a procedure. However, oesophagectomy is not without risk, and every patient must be fully informed of all associated risks. Reported mortality rates of 5–10% are described, while morbidity rates of up to 50% have been reported, and anastomotic leak in 10–20% of patients. Patients must also be informed of longer-term complications. Anastomotic stricture has been reported in up to 50% of patients, depending on length of post-operative follow-up. Dumping syndrome, reported in up to 20% of patients, tends to be self-limiting and may be managed medically if necessary, and vagal-sparing oesophagectomy may reduce this risk.
Mechanism
The cause of most cases of achalasia is unknown. LES pressure and relaxation are regulated by excitatory and inhibitory 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.
Diagnosis
Due to the similarity of symptoms, achalasia can be mistaken for more common disorders such as gastroesophageal reflux disease, 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, 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.
Barium swallow
The patient swallows a barium solution, with continuous fluoroscopy to observe the flow of the fluid through the esophagus. Normal peristaltic movement of the esophagus is not seen. There is acute tapering at the lower esophageal sphincter and narrowing at the gastro-esophageal junction, producing a "bird's beak" or "rat's tail" appearance. The esophagus above the narrowing is often dilated to varying degrees as the esophagus is gradually stretched over time. An air-fluid margin is often seen over the barium column due to the lack of peristalsis. A five-minutes timed barium swallow can provide a useful benchmark to measure the effectiveness of treatment.Esophageal manometry
Because of its sensitivity, manometry is considered the key test for establishing the diagnosis. A catheter is inserted through the nose, and the patient is instructed to swallow several times. The probe measures muscle contractions in different parts of the esophagus during the act of swallowing. Manometry reveals failure of the LES to relax with swallowing and lack of functional peristalsis in the smooth muscle esophagus.Characteristic manometric findings are:
- Lower esophageal sphincter fails to relax upon wet swallow
- Pressure of LES <26 mm Hg is normal, >100 is considered achalasia, > 200 is nutcracker achalasia.
- Aperistalsis in esophageal body
- Relative increase in intra-esophageal pressure as compared with intra-gastric pressure
Biopsy
Treatment
significantly improves outcomes in 75% of people with mild or moderate disease. It was classically considered that surgical myotomy provided greater benefit than either botulinum toxin or dilation in those who fail medical management. However, a recent randomized controlled trial found pneumatic dilation to be non-inferior to laparoscopic Heller myotomy.Lifestyle changes
Both before and after treatment, achalasia patients may need to eat slowly, chew very well, drink plenty of water with meals, and avoid eating near bedtime. Raising the head off the bed or sleeping with a wedge pillow promotes emptying of the esophagus by gravity. After surgery or pneumatic dilatation, proton pump inhibitors are required to prevent reflux damage by inhibiting gastric acid secretion, and foods that can aggravate reflux, including ketchup, citrus, chocolate, alcohol, and caffeine, may need to be avoided. If untreated or particularly aggressive, irritation and corrosion caused by acids can lead to Barrett's esophagus.Medication
Drugs that reduce LES pressure are useful. These include calcium channel blockers such as nifedipine and nitrates such as isosorbide dinitrate and nitroglycerin. However, many patients experience unpleasant side effects such as headache and swollen feet, and these medications often stop helping after several months.Botulinum toxin may be injected into the lower esophageal sphincter to paralyze the muscles holding it shut. As in the case of cosmetic botox, the effect is only temporary and lasts about 6 months. Botox injections cause scarring in the sphincter which may increase the difficulty of later Heller myotomy. This therapy is recommended only for patients who cannot risk surgery, such as elderly people in poor health. Pneumatic dilatation has a better long term effectiveness than botox.