What are early and late pathologies in achalasia evaluation, based on the type of achalasia (Lower Esophageal Sphincter - LES) disease?

Early vs. Late Pathology in Achalasia Based on Type

In achalasia evaluation, Type I and Type II achalasia typically represent later disease stages, while Type III achalasia and esophagogastric junction (EGJ) outflow obstruction often represent early or incompletely evolved disease. 1

Understanding Achalasia Progression

Achalasia evolves over a variable timespan with progressive neuronal loss in the esophageal myenteric plexus. The pathological progression can be understood through the Chicago Classification subtypes:

Early Pathology

• Type III (Spastic) Achalasia: Often represents early or evolving disease

  • Characterized by premature (spastic) contractions
  • Latency between upper sphincter relaxation and distal esophageal contraction <4.5 seconds
  • May be mistaken for esophageal spasm before high-resolution manometry (HRM)
  • Poorest response to all treatments 1

• EGJ Outflow Obstruction:

  • Can be early or incomplete achalasia (12%-40% of cases)
  • May resolve spontaneously
  • Can evolve into Type III achalasia 2
  • Abnormal functional luminal imaging probe (FLIP) distensibility or esophageal pressurization supports an achalasia diagnosis

Late Pathology

• Type I (Classic) Achalasia:

  • Represents more advanced disease with negligible pressurization within the esophagus
  • Often misdiagnosed before HRM due to esophageal shortening and pseudorelaxation
  • Shows aganglionosis of the myenteric plexus
  • May have very low LES pressure and integrated relaxation pressure (IRP) in end-stage disease 2

• Type II Achalasia:

  • Most common presenting subtype
  • Characterized by panesophageal pressurization
  • Shows uniform simultaneous pressurization bands spanning from upper to lower sphincter
  • Generally has the best response to therapy 1

Diagnostic Challenges

• Early in the disease, maneuvers that unmask impaired inhibitory innervation (multiple rapid swallows, rapid drink challenge) may help support diagnosis 2
• Late in the disease, both LES pressure and IRP might be very low, potentially leading to misdiagnosis as absent contractility
• Functional luminal imaging probe technology and presence of stasis on barium esophagram can help establish diagnosis in late-stage cases 2

Treatment Considerations Based on Disease Stage

• Early Disease (Type III):

  • POEM (Per-Oral Endoscopic Myotomy) is preferred as it allows for a longer myotomy 2, 1
  • This is particularly important for addressing the distal smooth muscle esophagus involvement

• Late Disease (Types I and II):

  • Both pneumatic dilation and laparoscopic Heller myotomy (LHM) are highly efficacious 1
  • POEM is also a viable option with comparable efficacy to LHM 2

Clinical Pearls and Pitfalls

• Diagnostic Pitfalls:

  • Early achalasia may be misdiagnosed as GERD due to focus on regurgitation symptoms
  • Type I achalasia may have IRP below upper limit of normal, especially in end-stage disease
  • Type III achalasia can mimic distal esophageal spasm

• Treatment Pitfalls:

  • Most published treatment trials exclude end-stage cases 2
  • Post-POEM patients have high risk of developing reflux esophagitis and should be advised about potential indefinite PPI therapy and/or surveillance endoscopy 2, 1

• Monitoring Considerations:

  • Late complications include megaesophagus and increased risk of esophageal carcinoma 1
  • Significant weight loss warrants urgent evaluation as it may indicate disease progression 1

Understanding the pathological progression of achalasia and correctly identifying the disease stage is crucial for selecting the most appropriate treatment strategy and optimizing patient outcomes.