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Idiopathic achalasia (IA) is a primary esophageal motor disorder characterized by loss of esophageal peristalsis and insufficient lower esophageal sphincter (LES) relaxation in response to deglutition.
IA is a rare disease with an annual incidence of approximately 1/200,000 to 1/59,000 and a prevalence rate recently estimated to be 1/10,000. There is no gender predilection and the peak incidence occurs between 30 and 60 years of age. There is some suspicion of differences between ethnic groups.
IA is characterized predominantly by dysphagia to solids and liquids, bland regurgitation often unresponsive to an adequate trial of proton pump inhibitor (PPI), and chest pain. Weight loss (usually between 5 and 10 kg) is present in most, but not all patients. Heartburn occurs in 27%-42% of IA patients. They are more likely to suffer from autoimmune disorders (diabetes mellitus, hypothyroidism, Sjögren syndrome, lupus erythematosus; see these terms).
Although the precise etiology is unknown, it is often thought to be either autoimmune, viral immune, or neurodegenerative. Some familial cases have been reported, but the rarity of familial occurrence does not support the hypothesis that genetic inheritance is a significant etiologic factor. IA has been associated with viral infections and auto-antibodies against myenteric plexus have been found, but the causal relationship remains unclear.
Lack of response to proton pump inhibitor therapy in a patient initially diagnosed as gastroesophageal reflux disease (GERD) should raise suspicion for motility disorders such as IA, especially if dysphagia is an accompanying complaint. The diagnosis is based on history of the disease, radiography (barium esophagogram), and esophageal motility testing (esophageal manometry). Endoscopic assessment of the gastroesophageal junction and gastric cardia is necessary to rule out malignancy. Newer diagnostic modalities such as high resolution manometry (HRM) help in predicting treatment response in achalasia based on esophageal pressure topography patterns identifying three phenotypes of achlasia (I-III) and outcome studies suggest better treatment response with types I and II compared to type III.
A majority of patients are misdiagnosed as having reflux disease given regurgitation. The differential diagnosis of a patient with dysphagia and regurgitation includes GERD, esophageal spasm, pseudoachalasia (associated to malignancies), and possibly eosinophilic esophagitis (see this term).
Management and treatment
Although IA cannot be permanently cured, excellent outcomes are achieved in over 90% of patients. Current medical and surgical therapeutic options (pneumatic dilation, surgical myotomy, and pharmacologic agents) aim at reducing the LES pressure and facilitating esophageal emptying by gravity and hydrostatic pressure of retained food and liquids. Either graded pneumatic dilatation (PD) or laparoscopic surgical myotomy with a partial fundoplication are recommended as initial therapy guided by patient age, gender, preference, and local institutional expertise. Botulinum toxin therapy is less effective than PD or surgical myotomy and is commonly reserved for patients who are not candidates for definitive therapies.
The prognosis in IA patients is excellent. Most patients with IA who are appropriately treated have a normal life expectancy but the disease does recur and the patient may need intermittent treatment.