Achalasia

Achalasia is a failure of the lower esophageal sphincter (LES) to relax that is caused by the degeneration of inhibitory neurons within the esophageal wall. It is classified as either primary (idiopathic) or secondary (in the context of another disease). In patients with achalasia, the chief complaint is dysphagia to both solids and liquids, although regurgitation, retrosternal pain, and weight loss may also occur. Upper endoscopy, esophageal barium swallow, and esophageal manometry play complementary roles in the diagnosis of achalasia. While upper endoscopy and/or esophageal barium swallow are often obtained initially, manometry usually confirms the diagnosis, and upper endoscopy is indicated to rule out a malignant underlying cause. In good surgical candidates, achalasia is usually treated with pneumatic dilation or myotomy. In most other cases, an injection of botulinum toxin is attempted. If these measures fail to provide relief, medical therapy (e.g., nifedipine) is indicated.

• Esophageal motility disorder characterized by inadequate relaxation of the lower esophageal sphincter (LES) and nonperistaltic contractions in the distal two-thirds of the esophagus due to the degeneration of inhibitory neurons
• Etymology: A (absent) -chalasia (relaxation)

• Rare disorder (∼ 1.6/100,000 individuals) ^[1]
• Most commonly occurs in middle-aged individuals

Epidemiological data refers to the US, unless otherwise specified.

• Primary achalasia (most common): cause is unknown ^[2]
• Secondary achalasia (pseudoachalasia): the presentation and manometric findings of a mechanical cause of obstruction (e.g., a malignancy) that mimics achalasia
  • Esophageal cancer ^[3]
  • Stomach cancer and other extraesophageal cancers (symptoms may be due to mass effect or paraneoplasia)
  • Chagas disease ^[4]
  • Amyloidosis ^[5]
  • Neurofibromatosis type I ^[6]
  • Sarcoidosis ^[7]

CHAgas disease may lead to secondary aCHAlasia.

• Swallowing is controlled through excitatory (acetylcholine, substance P) and inhibitory (NO, VIP) neurohumoral substances.
• Atrophy of inhibitory neurons in the Auerbach plexus → lack of inhibitory neurotransmitters (e.g., NO, VIP) → inability to relax and increased resting pressure of the LES, as well as dysfunctional peristalsis → esophageal dilation proximal to LES

• Dysphagia to solids and liquids; can be progressive; or paradoxical dysphagia (difficulty swallowing liquids, while solids are easily swallowed)
• Regurgitation
• Retrosternal pain and cramps
• Weight loss

Achalasia typically manifests with progressive dysphagia to solids and liquids while esophageal obstruction manifests with dysphagia to solids only.

• Approach
  • In general, all patients with suspected achalasia should initially undergo upper endoscopy and/or esophageal barium swallow; findings may support the diagnosis.
  • Esophageal manometry is indicated to establish the diagnosis (confirmatory test of choice), irrespective of the initial imaging findings.
  • If manometry is inconclusive and an esophageal barium swallow was not obtained initially, esophagram can also play a confirmatory role.
  • Endoscopy should be performed to rule out pseudoachalasia because the presentation and manometric findings of a mechanical cause of obstruction (e.g., a malignancy) may mimic achalasia.
• Esophageal barium swallow: supportive and/or confirmatory test ^[8]
  • Bird-beak sign: dilation of the proximal esophagus with stenosis of the gastroesophageal junction
  • Delayed barium emptying or barium retention
• Upper endoscopy: to rule out pseudoachalasia
  • Usually normal
  • May show retained food in esophagus or increased resistance of LES during passage with endoscope ^[8]
  • If malignancy is suspected, biopsy and endoscopic ultrasound are indicated
• Esophageal manometry: confirmatory test of choice
  • Peristalsis is absent or uncoordinated in the lower two-thirds of the esophagus.
  • Incomplete or absent LES relaxation
  • High LES resting pressure
  • No evidence of mechanical obstruction
• Chest x-ray
  • Widened mediastinum
  • Air-fluid level on lateral view
  • Possible absence of gastric air bubble

Differential diagnoses of achalasia

• Esophageal cancer
• Schatzki ring
• Esophageal stricture
• Chagas disease
• Extrinsic compression (e.g., mediastinal lymphadenopathy)
• Scleroderma

Esophageal motility disorders

• Esophageal motility disorders include disorders of hypomotility (e.g., achalasia) and hypermotility (e.g., diffuse esophageal spasm). ^[9][10][11]
• Achalasia is the best described hypomotile esophageal disorder.
• Diffuse esophageal spasm and hypercontractile esophagus are the best described hypermotile esophageal disorders.
• Hypertensive peristalsis (nutcracker esophagus; super-squeeze esophagus)
  • Previously considered a hypermotile esophageal disorder; manifests with retrosternal chest pain and dysphagia
  • On conventional esophageal manometry, hypertensive peristalsis is characterized by propagative high-amplitude (> 220 mm Hg) esophageal contractions.
    • With the emergence of high-resolution esophageal manometry (HRM), the clinical relevance of hypertensive peristalsis as a diagnosis has been questioned.
  • If HRM is not available and symptomatic patients are found to have esophageal peristalsis of an amplitude > 220 mm Hg, treatment is the same as for esophageal hypermotility disorders.

The differential diagnoses listed here are not exhaustive.

If a low surgical risk ^[8]

The preferred treatment often depends on the surgeon and the patient's situation. However, attempting pneumatic dilation before myotomy is gaining popularity because it is less invasive and the time of recovery is faster. This approach is already more popular in Europe.

• Pneumatic dilation
  • Endoscope-guided graded dilation of the LES that tears the surrounding muscle fibers with the help of a balloon
  • The success rate at one month is ∼ 85%; perforation risk is ∼ 2%.
• LES myotomy (Heller myotomy): a surgical procedure in which the lower esophageal sphincter is incised longitudinally to re-enable passage of food or liquids to the stomach.
• Peroral endoscopic myotomy
  • An endoscopy-guided myotomy of the inner circular muscular layer of the lower esophageal sphincter (the longitudinal muscle layer is preserved)
  • May be considered in other esophageal motility disorders (e.g., diffuse esophageal spasm) as well, in which case the myotomy incision may need to be extended into the esophageal body

If a high surgical risk

• Botulinum toxin injection in the LES
  • A good choice for patients who are poor surgical candidates
  • More than 50% of patients require treatment again within 6–12 months.
• If other measures are unsuccessful: nitrates or calcium channel blockers

• Pulmonary complications (e.g., pneumonia, abscess, asthma) caused by aspiration
• Megaesophagus
• Increased risk of esophageal cancer.

We list the most important complications. The selection is not exhaustive.