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Introduction
A neurogenic esophageal disorder of unknown cause characterized by impaired esophageal peristalsis and a lack of lower esophageal sphincter relaxation. Achalasia typically occurs in persons aged 20 to 40 years. However, a second peak occurs in the elderly. In achalasia, lower esophageal resting pressure is increased and intraesophageal pressure is increased relative to gastric pressure. The muscle and nerve components of the esophagus are abnormal. The primary defect appears to be a progressive loss of ganglion cells within the myenteric plexus of the esophageal wall.
Symptoms and Diagnosis
All patients with achalasia have dysphagia to solid foods; the majority of patients develop variable degrees of weight loss and dysphagia to liquids. About 60 to 90% of patients regurgitate undigested food into the esophagus shortly after a meal. Regurgitation may cause nocturnal coughing and aspiration. About 30 to 50% of patients have chest pain associated with eating. Elderly patients may have had symptoms for months or years before diagnosis. Complications include weight loss with advanced disease and coughing, bronchospasm, and pneumonia from aspirating esophageal contents.
Achalasia is often suspected from the history. In the early stages of the disease, chest x-ray findings can be normal. In the later stages, chest x-rays can show a dilated esophagus (mega-esophagus) with an air-fluid level caused by retained food and saliva. Elderly patients with a long history of achalasia can have a dilated and tortuous esophagus with a "bird-beak" narrowing at the gastroesophageal junction on barium swallow. Esophageal manometry usually shows the motility abnormalities.
Endoscopy can eliminate the possibility of pseudo-achalasia, which should be considered when patients are > 50 years, have had dysphagia for < 1 year, and have lost > 15 lb (> 7 kg). Other disorders that can mimic achalasia include malignancy, amyloidosis, sarcoidosis, Chagas' disease, and postvagotomy disturbances. Achalasia must also be differentiated from diffuse esophageal spasm, which more typically affects younger patients.
Treatment
Treatment is directed at relieving symptoms and preventing complications. Various drugs that can decrease lower esophageal sphincter pressure (eg, anticholinergics, amyl nitrite, nitroglycerin, 
2-agonists) have been used, but results have been inconsistent. Anticholinergics are particularly difficult to use in the elderly because of their adverse effects. Isosorbide nitrate (5 to 10 mg po before meals) or nitroglycerin (0.4 mg sublingually 5 minutes before meals) rapidly decreases lower esophageal sphincter pressure and may lessen dysphagia during meals. However, most patients with achalasia require more definitive treatment.
Botulinum toxin, an inhibitor of the release of acetylcholine, can be injected endoscopically into the lower esophageal sphincter. This relatively new treatment appears to approach the success rate of pneumatic dilatation. The most benefit seems to occur in patients > 50. The effects last 6 to 24 months; injection often needs to be repeated.
Mechanical disruption of the lower esophageal sphincter using pneumatic dilatation or surgical myotomy has been the principle method of treatment when drug treatment and botulinum toxin have not been effective. About 60% of patients have a good response with pneumatic dilatation; success rates > 95% have been reported. Elderly patients and patients with a long history of achalasia seem to have the most favorable responses. Twenty to 40% of patients require repeated dilatations. The incidence of immediate complications is 1 to 16%. Perforation occurs in 1 to 13%; in most of these cases, the perforation is small and localized.
Surgical myotomy is indicated when repeated pneumatic dilatations over a relatively short duration are necessary to maintain lower esophageal sphincter patency. Surgical myotomy reduces lower esophageal sphincter pressure more dependably than pneumatic dilatation but causes more complications. A modified Heller's procedure (anterior myotomy of the circular muscle fibers of the lower esophageal sphincter, preserving the sphincter competency) is successful in 80 to 90% of patients. This procedure is increasingly being performed laparoscopically or with video-assisted thorascopic surgery. The most significant complications are gastroesophageal reflux disease (< 10%) and persistence of severe dysphagia (< 10%).
Bron
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