Question 7: Chicago Classification for Achalasia - Subtypes, Treatment Choice & Prognosis

Background: What is Achalasia?

The Chicago Classification (v3.0/4.0)

1. Elevated integrated relaxation pressure (IRP) - the 4-second mean nadir EGJ pressure during a swallow exceeds the upper limit of normal (>15 mmHg in supine position)
2. Aperistalsis - complete absence of normal peristalsis in the smooth muscle esophagus

Type I - Classic Achalasia ("minimal pressurization")

• Incomplete LES relaxation + aperistalsis + no significant esophageal pressurization
• Esophageal body is essentially isobaric at atmospheric/gastric pressure
• Typically represents later disease with an already dilated, atonic esophagus
• The manometric tracing shows a "quiet" esophageal body between a persistently elevated EGJ pressure band

Type II - Achalasia with Panesophageal Pressurization

• Incomplete LES relaxation + aperistalsis + panesophageal pressurization in ≥20% of swallows (pressurization ≥30 mmHg extending from UES to EGJ)
• Represents fluid/air trapped between the UES and non-relaxing LES being compressed as the esophagus shortens
• Most common subtype in clinical practice
• Represents earlier disease before the esophagus dilates

Type III - Spastic Achalasia

• Incomplete LES relaxation + premature (spastic) lumen-obliterating contractions in ≥20% of swallows
• Contractions are rapidly propagated but are not true peristalsis; they represent distal esophageal spasm superimposed on aperistalsis
• Distinct pathogenesis: myenteric plexus inflammation/dysfunction without ganglion cell destruction (unlike Types I/II)
• Patients typically present with chest pain in addition to dysphagia

How Subtype Influences Treatment Choice and Prognosis

Type I (Classic Achalasia)

• Treatment: LHM with partial fundoplication (Dor or Toupet) or POEM are the standard approaches. Pneumatic dilation is less effective here compared to Type II.
• Prognosis: Intermediate. Response to therapy is generally good but not as reliable as Type II. The dilated, atonic esophagus may not recover normal dimensions even after successful LES disruption.

Type II (Achalasia with Compression)

• Treatment: This subtype has the best prognosis and responds to virtually all modalities. The pivotal European RCT (multicenter) found that pneumatic dilation achieved 100% efficacy for Type II versus 93% for LHM (p = 0.03). Given comparable perforation risk (~1%) and significantly lower cost, pneumatic dilation is the preferred initial treatment for Type II achalasia.
• POEM is equally effective and a valid alternative.
• Prognosis: Best of the three subtypes. Excellent response rates with PD, LHM, and POEM.

Type III (Spastic Achalasia)

• Treatment: This subtype has a unique therapeutic niche for POEM. Because Type III involves spastic contractions that may extend well above the EGJ, the myotomy must be longer (average 16 cm with POEM vs. 8 cm with LHM). POEM is not anatomically limited by the diaphragm and allows extension of the myotomy proximally along the entire spastic segment.
  • In a retrospective analysis of 49 Type III patients treated with POEM vs. 26 with LHM, POEM achieved clinical success in 98% vs. 80% with surgical myotomy.
  • Both LHM and POEM are effective for Types I and II, but POEM is superior to LHM for Type III (Sabiston).
  • Pneumatic dilation is notably least effective for Type III (40% success in one series vs. 86% for LHM).
• Prognosis: Historically the worst prognosis with conventional therapy; substantially improved with POEM.

Summary Table: Subtype, Treatment of Choice, and Prognosis

Note on POEM and Reflux

Question 8: Complications of Achalasia (6 marks)

1. Aspiration Pneumonia / Pulmonary Complications

• Retained food and saliva in a dilated esophagus pool overnight and aspirate into the tracheobronchial tree
• Leads to recurrent aspiration pneumonia, lung abscess, bronchiectasis, and progressive pulmonary fibrosis in severe/longstanding cases
• Aspiration is especially common at night (supine position) and in Type I with a massively dilated esophagus

2. Esophageal Squamous Cell Carcinoma (SCC)

• The most feared long-term complication
• Chronic stasis leads to fermentation of retained food, mucosal irritation, and chronic esophagitis, promoting malignant transformation
• Risk of SCC in long-standing achalasia is estimated at 1-33% of patients (up to 15 times the general population)
• SCC typically develops in the mid-esophagus (site of maximal stasis)
• No consensus exists on optimal surveillance endoscopy intervals

3. Adenocarcinoma (Post-treatment)

• Can develop as a consequence of Barrett's esophagus following treatment-related GERD (especially post-POEM or post-LHM without adequate fundoplication)
• Represents a treatment complication rather than a disease-intrinsic complication

4. Megaesophagus / End-Stage Achalasia

• Progressive dilation leads to a massively dilated, tortuous, sigmoid-shaped esophagus
• Esophageal function is irreversibly lost
• Management becomes very challenging; esophagectomy may be the only viable option
• Indications for esophagectomy: pronounced esophageal dilation, severe dysphagia refractory to LES-directed therapy, esophageal sump, peptic stricture not amenable to dilation, recurrent aspiration, and perforation during dilation

5. Esophageal Perforation (Iatrogenic)

• Occurs in approximately 1% of cases with either pneumatic dilation or surgical myotomy
• Perforation during PD is the most feared acute complication of endoscopic treatment
• May require emergency surgical repair or esophageal stenting

6. Gastroesophageal Reflux Disease (GERD) and Peptic Stricture

• Paradoxically, over-treatment (excessive LES disruption without adequate antireflux protection) leads to GERD
• Pathologic acid exposure occurs in ~50% after POEM, ~20% after LHM without fundoplication, and ~9% after LHM with partial fundoplication
• Complications of GERD include: peptic stricture (may require surgical intervention), Barrett's esophagus, and esophageal adenocarcinoma
• All achalasia patients treated with POEM or myotomy should undergo pH testing 3-6 months post-procedure

7. Candida Esophagitis

• Stasis of food in the esophagus creates an ideal environment for fungal overgrowth
• Candida esophagitis is a recognized complication of untreated or poorly treated achalasia
• May also complicate post-treatment surveillance

8. Epiphrenic Diverticulum

• A pulsion diverticulum that can form from the raised intraluminal pressure proximal to the non-relaxing LES
• May cause additional dysphagia, regurgitation, and aspiration
• Treated with diverticulectomy + myotomy (laparoscopic or D-POEM)

Summary of Complications