Achalasia Diagnosis and Treatment

Introduction to Achalasia Subtypes

The Chicago Classification system defines achalasia subtypes based on high-resolution manometry (HRM) patterns in patients with impaired deglutitive lower esophageal sphincter (LES) relaxation and absent peristalsis, with Type II having the best treatment response and Type III the poorest 1, 2
The American Gastroenterological Association recommends the Chicago Classification system for staging achalasia, which categorizes achalasia into three distinct subtypes (Type I, II, and III) based on esophageal body pressurization patterns and contractility 1, 2

Type I achalasia is characterized by minimal or negligible pressurization within the esophageal body, representing a decompensated, dilated esophagus 1, 2, 3
Type II achalasia is characterized by panesophageal pressurization with uniform simultaneous pressurization bands spanning from upper to lower sphincter, and has the best response to all forms of therapy (botulinum toxin, pneumatic dilation, or myotomy) 1, 2, 4, 3
Type III achalasia is characterized by premature (spastic) contractions with distal latency <4.5 seconds between upper sphincter relaxation and arrival of rapidly propagated contraction, and has the poorest response to all treatments 1, 2, 4, 3

The Chicago Classification version 4.0 requires abnormal median integrated relaxation pressure (IRP) in the primary position with wet swallows and 100% failed peristalsis for a conclusive achalasia diagnosis 3
The IRP sensitivity is <100%, particularly in Type I disease where LES pressure may be very low, and specificity is <100% as instances with preserved peristalsis can occur 1

While subtyping provides prognostic information, there is insufficient evidence to recommend specific therapies based on subtype alone, especially between Type I and Type II, except for Type III achalasia where POEM with longer myotomy is preferred 4, 3, 1, 5, 6
Treatment decisions should incorporate Chicago Classification subtype, patient comorbidities, early versus late disease stage, primary or secondary causes, and local expertise and therapeutic availability 5, 6, 1, 4