What Is Achalasia?
Achalasia is a motility disorder of the oesophagus (the tube that carries food from the mouth to the stomach). In achalasia, the muscle of the lower oesophagus and the lower oesophageal sphincter (the ring of muscle at the junction of the oesophagus with the stomach) fail to relax and let food pass into the stomach. This causes difficulty swallowing food.
Achalasia is quite rare and typically occurs in adults aged 25-60 years.
What causes achalasia?
The cause of achalasia is unknown. Theories on causation invoke infection, heredity or an abnormality of the immune system that causes the body itself to damage the esophagus (autoimmune disease).
The esophagus contains both muscle and nerves. The nerves coordinate the relaxation and opening of the sphincters as well as the peristaltic waves in the body of the esophagus. Achalasia has effects on both the muscles and nerves of the esophagus; however, the effects on the nerves are believed to be the most important. Early in achalasia, inflammation can be seen under the microscope in the muscle of the lower esophagus, especially around the nerves. As the disease progresses, the nerves begin to degenerate and ultimately disappear, particularly the nerves that cause the lower esophageal sphincter to relax. Still later in the progression of the disease, muscle cells begin to degenerate, possibly because of the damage to the nerves. The result of these changes is a lower sphincter that cannot relax and muscle in the lower esophageal body that cannot support peristaltic waves. With time, the body of the esophagus stretches and becomes very enlarged (dilated).
How is achalasia treated?
Treatments for achalasia include oral medications, dilation or stretching of the lower esophageal sphincter (dilation), surgery to cut the sphincter (esophagomyotomy), and the injection of botulinum toxin (Botox) into the sphincter. All four treatments reduce the pressure within the lower esophageal sphincter to allow easier passage of food from the esophagus into the stomach.
Oral medications
Oral medications that help to relax the lower esophageal sphincter include groups of drugs called nitrates, e.g., isosorbide dinitrate (Isordil) and calcium-channel blockers, e.g., nifedipine (Procardia) and verapamil (Calan). Although some patients with achalasia, particularly early in the disease, have improvement of symptoms with medications, most do not. By themselves, oral medications are likely to provide only short-term and not long-term relief of the symptoms of achalasia, and many patients experience side-effects from the medications.
Dilation
The lower esophageal sphincter also may be treated directly by forceful dilation. Dilation of the lower esophageal sphincter is done by having the patient swallow a tube with a balloon on the end. The balloon is placed across the lower sphincter with the help of x-ray, and the balloon is blown up suddenly. The goal is to stretch--actually to tear--the sphincter. The success of forceful dilation has been reported to be between 60 and 95%. Patients in whom dilation is not successful can undergo further dilations, but the rate of success decreases with each additional dilation. If dilation is not successful, the sphincter may still be treated surgically. The main complication of forceful dilation is rupture of the esophagus, which occurs 5% of the time. Half of the ruptures heal without surgery, though patients with rupture who do not require surgery still must be followed closely and treated with antibiotics. The other half of ruptures require surgery. (Although surgery carries additional risk for the patient, surgery can repair the rupture as well as permanently treat the achalasia with esophagomyotomy.) Death following forceful dilation is rare. Dilation is fast, inexpensive compared with surgery, and requires only a short hospital stay.
Esophagomyotomy
The sphincter also can be cut surgically, a procedure called esophagomyotomy. The surgery can be done using a large abdominal incision or laparoscopically through small punctures in the abdomen. In general, the laparoscopic approach is used with uncomplicated achalasia. Alternatively, the surgery can be done with a large incision or laparoscopically through the chest. Esophagomyotomy is more successful than forceful dilation, probably because the pressure in the lower sphincter is reduced to a greater extent and more reliably; 80-90% of patients have good results. With prolonged follow-up, however, some patients develop recurrent dysphagia. Thus, esophagomyotomy does not guarantee a permanent cure. The most important side effect from the more reliable and greater reduction in pressure with esophagomyotomy, is reflux of acid (gastroesophageal reflux disease or GERD). In order to prevent this, the esophagomyotomy may be modified so that it doesn't completely cut the sphincter or the esophagomyotomy may be combined with anti-reflux surgery (fundoplication). Whichever surgical procedure is done, some physicians recommend life-long treatment with oral medications for acid reflux. Others recommend 24 hour esophageal acid testing with lifelong medication only if acid reflux is found.
Botulinum toxin
The newest treatment for achalasia is the endoscopic injection of botulinum toxin into the lower sphincter to weaken it. Injection is fast, nonsurgical, and requires no hospitalization. Treatment with botulinum toxin is safe, but the effects on the sphincter often last only for months, and additional injections with botulinum toxin may be necessary. Injection is a good option for patients who are very elderly or are at high risk for surgery, e.g., patients with severe heart or lung disease. It also allows patients who have lost substantial weight to eat and improve their nutritional status prior to “permanent” treatment with surgery. This may reduce post-surgical complications.