Achalasia: Description, Causes and Risk Factors:
Failure to relax; referring especially to visceral openings such as the pylorus, cardia, or any other sphincter muscles.
Achalasia is an esophageal motor disorder characterized by aperistalsis of the esophageal body and lack of relaxation of the lower sphincter in response to swallows. It affects both sexes and all age groups. Achalasia is a Greek word that means "failure of relaxation." Achalasia can be primary (idiopathic) or secondary. In secondary achalasia, the cause for the degeneration of esophageal nerve fibers is known. Pathophysiologically, achalasia is caused by loss of inhibitory ganglion cells in the myenteric plexus. Since the initial description, several studies have attempted to explore initiating agents that may cause the disease such as viral infection, other environmental factors, autoimmunity, and genetic factors. However, the exact pathogenesis of primary achalasia is still not known.
Achalasia was first described by Willis in 1674 as "food blockage in esophagus". He treated these patients successfully with a dilator made of whale bone and sponge. The term “achalasia” was first coined by Hurst in 1927. He had observed such patients since 1914 and suggested that their disorder might be due to absence of normal relaxation of the sphincter, possibly resulting from organic changes in Auerbach's plexus (myenteric plexus).
Achalasia is caused by loss of inhibitory ganglion in the myenteric plexus in the esophagus. Gradual progression of neuronal degeneration is associated with progression of the disease from vigorous to classic achalasia. Though several studies have attempted to explore initiating agents that may cause the disease, the exact factors responsible for the degeneration of ganglion cells in the myenteric plexus are poorly understood. The disease is likely to be multi-factorial involving host genetic factors, autoimmunity, and environmental factors such as infections. More studies are needed to explore the exact cause of this enigmatic disease.
Achalasia may occur at any age; however, incidence peaks in individuals over the age of 60 or 70 years. There is equal gender distribution. Although several series have a female predominance, this may be due to greater numbers of older women.
The annual incidence of achalasia in the USA, approximately 0.6 per 100,000, has remained stable in recent decades. In British studies the incidence ranges between 0.4 and 1 per 100,000, rising to 3 per 100,000 for people aged >70 years.
The main symptoms are difficulty in swallowing to both solids and liquids food, chest pain, and regurgitation. It follows a very chronic course with progressive dysphagia and weight loss
The differential diagnosis of achalasia begins with the broad differential diagnosis of dysphagia and exclusion of mechanical causes of dysphagia. Strictures, benign neoplasm, vascular rings, webs, foreign bodies, and severe esophagitis (peptic, infectious, chemical, drug induced) are among the frequently encountered entities.
Other tests may include:
- Barium esophagogram.
- Ultrasonography, very rarely.
These tests allow the direct evaluation and inspection of the esophageal mucosa and an objective measurement of esophageal contractility.
The aim of treatment is to relieve the functional obstruction at the cardia. The two main methods are forceful dilation of the cardia and Heller's myotomy.
Pneumatic forceful dilatation involves stretching the cardia with a balloon to disrupt the muscle and render it less competent. The results have, however, been variable. Perforation is the major complication and has been reported in about 3 to 5% cases. The risk of perforation increases with the bigger balloons and they should be used cautiously for progressive dilatation over a period of weeks.
Heller's myotomy involves cutting the muscles of the lower esophagus and cardia. Heller's myotomy may be performed through an abdominal route or transthoracically. The left thoracotomy is the preferred approach. After the lower end of the esophagus is exposed and carefully mobilized to preserve the vagal nerve trunks. The muscle coat of the distal esophagus is divided longitudinally down to the esophageal mucosa. This incision extends 5 cm proximally and 2 cm distally to the esophagogastric junction. The incision is deepened up to the submucous coat only taking care not to damage the mucosa which bulges out throughout the gap. Carefully measured myotomy does not increase the incidence of gastro-esophageal reflux. In case there is a possibility that the lower sphincter has got destroyed and anti-reflux procedure may need to be added. It is desirable to perform a partial rather than a total fundoplication in this situation because of the risk of causing dysphagia in the presence of an aperistaltic esophagus.
Heller's myotomy is now being performed by a minimal access approach by either thoracoscopy or laparoscopy. It is a pain-free procedure and requires a short hospital stay.
Botulinum toxin is given by endoscopic injection into the cardio esophageal sphincter. It is a new form of treatment whose place is not yet established. It acts rapidly and strongly binds to presynaptic cholinergic nerve terminals and produces paralysis within a few hours. Transmission of neuromuscular impulses resumes after the growth of new axon terminals and clinical weakening of muscles is seen for several months.
Drugs, such as calcium channel antagonists may decrease pressure in the lower sphincter and may improve swallowing but its long term efficacy is doubtful. It may be useful for transient relief of symptoms.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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