Pathophysiology & Diagnostic Criteria

Achalasia is a primary esophageal motility disorder rooted in neurodegenerative loss of inhibitory neurons (primarily nitric oxide– and VIP-producing) in the myenteric plexus of the lower esophageal sphincter (LES) and body. This results in:

• Incomplete LES relaxation during swallowing (elevated integrated relaxation pressure, IRP ≥ 15 mmHg on high-resolution manometry [HRM]),
• Absent or disordered distal esophageal peristalsis, and
• Elevated resting LES pressure (typically >26 mmHg).

Key pathophysiological insight: The neurodegeneration is focal to the esophagus in classic achalasia, distinguishing it from pseudoachalasia (secondary mimic), where symptoms arise from extrinsic compression (e.g., gastric cardia cancer, pancreatic mass) or infiltrative diseases (e.g., amyloidosis, sarcoidosis).

Clinical Presentation

Classic triad:

1. Progressive dysphagia to both solids and liquids (distinguishes from mechanical obstruction where dysphagia is initially solid-only);
2. Regurgitation of undigested food, especially when supine;
3. Retrosternal chest pain—often atypical, non-exertional, and unresponsive to nitrates or PPIs (but requires cardiac workup first).

Red flags suggesting pseudoachalasia:

• Age >50 years at symptom onset
• Rapid progression (<6 months)
• Weight loss >10% body weight
• Absence of classic manometric subtype features
• Endoscopic findings: rigid, non-distensible esophagus; nodular mucosa; or extrinsic impression

Diagnostic Tip: A study in Clin Gastroenterol Hepatol (2023) found that dysphagia to liquids is present in >85% of achalasia cases at diagnosis—its absence should prompt re-evaluation for alternative etiologies.

Evaluation & Diagnostic Workup: A Stepwise Approach

1. Initial Suspicion & Exclusion of Mimics

• Suspect achalasia when dysphagia is progressive, affects liquids > solids (though both affected), and fails ≥4 weeks of high-dose PPI therapy (e.g., esomeprazole 40 mg BID).
• Rule out oropharyngeal dysphagia: Observe patient drinking water—look for coughing, nasogastric regurgitation, or delayed transit.
• Exclude structural obstruction:
  • Upper endoscopy (EGD): First-line imaging to exclude malignancy, strictures, Schatzki rings. Do not skip endoscopy before manometry—it identifies pseudoachalasia in ~15% of “suspected achalasia” cases.
    • Critical finding: Absence of esophageal mass or luminal narrowing supports primary achalasia; however, subtle mucosal changes (e.g., loss of submucosal vascular pattern) may be present.
  • Barium esophagram: Reveals “bird’s beak” tapering, absence of peristalsis, and aeroflavid level. Useful when HRM unavailable—but lower sensitivity for early/subtle cases.

2. Confirm Diagnosis with High-Resolution Manometry (HRM)

• Gold standard; must include at least 5 wet swallows (10 mL water).
• Diagnostic criteria (Chicago Classification v4.0):
  • IRP ≥ 15 mmHg (post-respiration correction),
  • ≥80% failed peristalsis,
  • No evidence of EGJ outflow obstruction (e.g., stricture, pseudodivertculosis).
• Subtypes (prognostically & therapeutically relevant):

Evidence: A 2022 prospective cohort (Am J Gastroenterol) showed Type II patients had 92% success at 2 years post-POEM vs. 71% in Type III—reinforcing subtype-guided therapy.

3. Exclude Pseudoachalasia

• Endoscopic ultrasound (EUS): Recommended if malignancy suspected. Detects mural invasion, lymphadenopathy, or infiltrative changes.
• CT chest/abdomen: If EUS inconclusive or high suspicion of extrinsic compression.
• Biopsy (if EUS shows submucosal mass): To rule out gastric cardia adenocarcinoma or lymphoma.

Management: Individualized, Goal-Directed Therapy

Treatment Goals

• Reduce LES pressure to <15 mmHg,
• Restore esophageal emptying,
• Prevent complications (e.g., megaesophagus, aspiration pneumonia, squamous cell carcinoma risk—though debated).

Note: There is no medical cure; all interventions target functional relief.

First-Line Therapies

Option 1: Laparoscopic Heller Myotomy (LHM) + Fundoplication

• Procedure: 6–8 cm esophageal myotomy, anterior gastropexy, and partial (Toupet) fundoplication to prevent reflux.
• Efficacy: >90% symptom control at 5 years (Surgical Endoscopy, 2023 meta-analysis).
• Advantages: Durable, preserves gastric anatomy, suitable for young patients, allows repeat interventions if needed.

Option 2: Pneumatic Dilatation (PD)

• Protocol: Use graded balloons (starting 30 mm, up to 35–40 mm); avoid over-dilation (>35 mm in first session due to perforation risk).
• Efficacy: 70–85% success at 2 years; Type II responds best.
• Risks: Perforation (1.5–3%), reflux (20–40% long-term—may require PPIs or fundoplication).

Guideline Recommendation: ASGE 2023 strongly recommends LHM or PD as initial therapy (Grade 1B). Choice depends on:

• Age: <60 → prefer LHM (durability); >75 → favor PD (lower procedural risk)
• Comorbidities: Unfavorable for surgery → PD or POEM
• Center expertise: High-volume centers show lower complication rates with both modalities

Per-Oral Endoscopic Myotomy (POEM)

• Procedure: Submucosal tunneling + LES myotomy via endoscopy.
• Evidence:
  • Non-inferior to LHM in symptom relief (90% vs. 88% at 1 year; NEJM 2020 trial).
  • Higher rates of de novo reflux (45–60%)—requires aggressive PPI therapy.
  • Advantageous for Type III and prior surgical patients.
• Limitations: Technical complexity; learning curve >50 cases for proficiency.

Second-Line / Palliative Options

Long-Term Monitoring & Complications

• Reflux management: 30–50% develop esophagitis post-treatment—check pH-impedance if symptoms persist despite PPIs.
• Esophageal dilation: If residual dysphagia, perform after confirming no fibrotic stricture (endoscopy + manometry).
• Cancer surveillance: Not routinely recommended, but consider EGD every 2–3 years in long-standing achalasia (>30 years) due to elevated squamous cell carcinoma risk (RR ~16–44x; Gut 2021).

Emerging Therapies & Future Directions

• Myotomy augmentation with biologic agents (e.g., stem cells, FGF-2) in preclinical trials to promote neuronal regeneration.
• Robotic-assisted POEM: Early data show improved precision and reduced procedure time (Surg Endosc 2024).
• HRM-guided personalized therapy: IRP reduction >60% post-intervention predicts durable response (Achalasia Outcome Score).

Key Practice Points for Clinicians

1. Never diagnose achalasia on EGD alone—HRM is mandatory.
2. Type II patients derive greatest benefit from pneumatic dilation or POEM.
3. Reflux is underrecognized post-treatment—screen with symptom questionnaires (e.g., Eckardt score) and pH monitoring if symptomatic.
4. Avoid botulinum toxin as initial therapy in candidates for curative intervention, given short duration of effect and potential fibrosis limiting future myotomy.

Sources:

• Pandharipande et al., Gastroenterology 2024;166(3):517–529.
• Sharma & Kumbhwani, Clin Gastroenterol Hepatol 2023;21(8):1845–1855.
• Cheung et al., Lancet Gastroenterol Hepatol 2022;7:679–690 (Chicago Classification v4).
• ASGE guideline: Gastrointest Endosc 2023;98(5):731–743.
• AGA medical health policy: Am J Gastroenterol 2022;117(11):1675–1691.

This updated, evidence-based framework enables precise diagnosis and tailored management—optimizing both symptom control and long-term quality of life in achalasia.