What is achalasia?

Achalasia: Definition, Diagnosis, and Management

Achalasia is a primary esophageal motility disorder characterized by impaired lower esophageal sphincter (LES) relaxation and absent peristalsis in the esophageal body, resulting in progressive dysphagia, regurgitation, and chest pain. 1 The condition is caused by autoimmune-mediated destruction of the myenteric plexus neurons in the esophagus, leading to aganglionosis and functional obstruction at the gastroesophageal junction.

Clinical Presentation

Patients with achalasia typically present with:

• Progressive dysphagia (difficulty swallowing)
• Regurgitation of undigested food
• Chest pain
• Weight loss
• Aspiration
• Less commonly: heartburn, chronic cough, and aspiration pneumonia 2

Pathophysiology

The primary pathological finding in achalasia is:

• Inflammation of the myenteric plexus leading to aganglionosis
• Strong evidence supporting an autoimmune component
• Potential triggers include viral infections (including SARS-CoV-2) in genetically susceptible individuals
• Associations with systemic sclerosis, Addison's disease, and other autoimmune conditions 1
• Can occur as a paraneoplastic manifestation in certain malignancies (lymphoma, lung cancer, breast cancer)

Classification

According to the Chicago Classification (v3.0), achalasia is categorized into three subtypes based on high-resolution manometry findings:

1. Type I (Classic): Non-compression subtype with a decompensated, dilated esophagus
2. Type II: Pan-esophageal compression; presumed to be the precursor to type I
3. Type III (Spastic): Associated with persistent peristalsis with spasm (previously known as vigorous achalasia) 3, 1

Type II is the most common presenting subtype and generally has the best response to therapy, while Type III has the poorest response to all treatments 3, 1.

Diagnostic Methods

Gold Standard: High-Resolution Manometry (HRM)

• Demonstrates absent peristalsis, impaired LES relaxation, and elevated integrated relaxation pressure (IRP)
• The 4-second IRP has 98% sensitivity and 96% specificity for detecting achalasia 3
• Allows for subtyping of achalasia, which has prognostic implications

Additional Diagnostic Tests

• Barium esophagram: Shows characteristic "bird's beak" appearance
• Endoscopy: Important to rule out mechanical obstruction or malignancy
• Serologic testing: For Chagas disease in patients with travel history to Central/South America
• Evaluation for autoimmune conditions: Particularly in patients with systemic symptoms 1

Treatment Options

Treatment aims to disrupt the LES to improve bolus passage, as there is no curative therapy. Options include:

1. Per-Oral Endoscopic Myotomy (POEM)

• First-line therapy for Type III achalasia
• Comparable to laparoscopic Heller myotomy for all achalasia subtypes
• High risk of developing reflux esophagitis post-procedure 1

2. Laparoscopic Heller Myotomy (LHM)

• Usually combined with partial fundoplication
• Highly effective for Type I and II achalasia 1

3. Pneumatic Dilation

• Effective particularly for Type I and II achalasia
• Better response in women and older patients
• May require repeat dilations over time 1

4. Pharmacological Options

• Calcium channel blockers and nitrates
• Limited efficacy, generally reserved for patients who are not candidates for more definitive procedures 4

5. Botulinum Toxin Injection

• Reserved for patients who cannot undergo balloon dilation and are not surgical candidates
• Temporary effect, requiring repeated treatments 4

Treatment Recommendations by Subtype

• Type I and II: Both pneumatic dilation and LHM are highly efficacious; POEM is also effective but may cause more reflux
• Type III: POEM is preferred, with myotomy length calibrated to the spastic segment 1

Post-Treatment Monitoring

• Surveillance for reflux symptoms, especially after POEM
• Consider proton pump inhibitor therapy and/or surveillance endoscopy
• Monitor for late complications, including megaesophagus and increased risk of esophageal carcinoma 1

Common Pitfalls in Diagnosis

1. Misdiagnosis as gastroesophageal reflux disease, delaying proper treatment
2. Failure to recognize achalasia subtypes, which affects treatment outcomes
3. Overlooking associated autoimmune conditions or potential paraneoplastic etiology
4. Integrated relaxation pressure (IRP) may be less than the upper limit of normal in some achalasia cases, leading to diagnostic challenges 1, 2

Early diagnosis and appropriate treatment selection based on achalasia subtype are crucial for optimizing outcomes and preventing complications such as esophageal dilation, aspiration pneumonia, and malnutrition.