Achalasia is an idiopathic motility disorder characterized by loss of peristalsis in the distal two-thirds (smooth muscle) of the esophagus and impaired relaxation of the LES. There appears to be denervation of the esophagus resulting primarily from loss of nitric oxide–producing inhibitory neurons in the myenteric plexus. The cause of the neuronal degeneration is unknown.
Normally, the muscles of the esophagus contract to squeeze food along towards the stomach. A ring of muscle at the end of the food pipe then relaxes to let food into the stomach.
In achalasia, the muscles in the esophagus do not contract correctly and the ring of muscle can fail to open properly, or does not open at all. Food and drink cannot pass into the stomach and becomes stuck. It is often brought back up.
Signs and symptoms
There is a steady increase in the incidence of achalasia with age; however, it can be seen in individuals as young as 25 years. Patients complain of the gradual onset of dysphagia for solid foods and, in the majority, of liquids also.
Symptoms at presentation may have persisted for months to years. Substernal discomfort or fullness may be noted after eating.
Many patients eat more slowly and adopt specific maneuvers such as lifting the neck or throwing the shoulders back to enhance esophageal emptying.
Regurgitation of undigested food is common and may occur during meals or up to several hours later.
Nocturnal regurgitation can provoke coughing or aspiration. Up to 50% of patients report substernal chest pain that is unrelated to meals or exercise and may last up to hours. Weight loss is common. Physical examination is unhelpful.
Chest radiographs may show an air-fluid level in the enlarged, fluid-filled esophagus. Barium esophagography discloses characteristic findings, including esophageal dilation, loss of esophageal peristalsis, poor esophageal emptying, and a smooth, symmetric “bird’s beak” tapering of the distal esophagus. Without treatment, the esophagus may become markedly dilated (“sigmoid esophagus”).
After esophagography, endoscopy is always performed to evaluate the distal esophagus and gastroesophageal junction to exclude a distal stricture or a submucosal infiltrating carcinoma. The diagnosis is confirmed by esophageal manometry. The manometric features are complete absence of normal peristalsis and incomplete lower esophageal sphincteric relaxation with swallowing. Using high-resolution esophageal topographic tracings, three achalasia subtypes are recognized. Type III is a spastic variant with less favorable treatment outcomes (66%) than types I (81%) or II (96%).
Chagas disease is associated with esophageal dysfunction that is indistinguishable from idiopathic achalasia and should be considered in patients from endemic regions (Central and South America); it is becoming more common in the southern United States. Primary or metastatic tumors can invade the gastroesophageal junction, resulting in a picture resembling that of achalasia, called “pseudoachalasia.” Endoscopic ultrasonography and chest CT may be required to examine the distal esophagus in suspicious cases.
Botulinum Toxin Injection: Endoscopically guided injection of botulinum toxin directly into the LES results in a marked reduction in LES pressure with initial improvement in symptoms in 65–85% of patients. However, symptom relapse occurs in over 50% of patients within 6–9 months and in all patients within 2 years. Because it is inferior to pneumatic dilation therapy and surgery in producing sustained symptomatic relief, this therapy is most appropriate for patients with comorbidities who are poor candidates for more invasive procedures.
Pneumatic Dilation: Up to 90% of patients derive good to excellent relief of dysphagia after one to three sessions of pneumatic dilation of the LES. Dilation is less effective in patients who are younger than age 45, have the type III variant, or have a dilated esophagus. Symptoms recur following pneumatic dilation in up to 35% within 10 years but usually respond to repeated dilation. Perforations occur in less than 3% of dilations and may require operative repair. The success of laparoscopic myotomy is not compromised by prior pneumatic dilation.
Surgery: A modified Heller cardiomyotomy of the LES and cardia results in good to excellent symptomatic improvement in over 90% of patients. Because gastroesophageal reflux develops in up to 20% of patients after myotomy, most surgeons also perform an antireflux procedure (fundoplication), and all patients are prescribed a once-daily proton pump inhibitor. Myotomy is performed with a laparoscopic approach and is preferred to the open surgical approach. Symptoms recur following cardiomyotomy in greater than 25% of cases within 10 years but usually respond to pneumatic dilation.