Key Facts

Achalasia is a primary oesophageal motility disorder characterised by impaired LOS relaxation and absent oesophageal peristalsis, leading to progressive dysphagia and food stasis in the oesophagus.

Epidemiology

Incidence is approximately 1.6 per 100,000 per year with a prevalence of ~10 per 100,000. Equal sex distribution. Can occur at any age but peak incidence is 30-60 years. No clear ethnic predisposition.

Aetiology

• Primary (idiopathic): vast majority; likely autoimmune destruction of inhibitory neurones
• Secondary (pseudo-achalasia): malignancy at GOJ (mimics achalasia — important to exclude in older patients with short symptom duration), Chagas disease (Trypanosoma cruzi — South America)
• Genetic: rare familial forms; association with Allgrove syndrome (achalasia, alacrima, adrenal insufficiency — triple A syndrome)

Pathophysiology

Selective loss of inhibitory neurones (producing nitric oxide and VIP) in the myenteric plexus, with relative preservation of excitatory cholinergic neurones. This results in:

1. Failure of LOS relaxation: persistent tonic contraction of the LOS
2. Absent peristalsis: loss of sequential contraction in the oesophageal body
3. Progressive oesophageal dilatation: food stasis, fermentation, aspiration risk

The aetiology of neuronal loss is unclear — likely autoimmune (CD3+ T-cell infiltration in myenteric plexus), possibly triggered by viral infection (HSV-1) in genetically susceptible individuals.

Typical Presentation

• Progressive dysphagia to solids AND liquids (key differentiator from mechanical obstruction)
• Regurgitation of undigested food (often hours after eating, or nocturnal)
• Chest pain/discomfort (particularly Type III achalasia)
• Weight loss (variable, usually gradual)
• Nocturnal cough (aspiration of retained food)

Manometric Subtypes

• Type I (classic): minimal oesophageal pressurisation, dilated oesophagus
• Type II (with compression): panesophageal pressurisation in >20% of swallows — best treatment response
• Type III (spastic): premature/spastic contractions — worst prognosis, most symptomatic

Red Flags

• Rapid onset in elderly (>55 years) with weight loss → exclude pseudo-achalasia (GOJ malignancy)
• Haematemesis (oesophageal ulceration from stasis)
• Recurrent aspiration pneumonia
• Rapidly progressive symptoms (<6 months duration — pseudo-achalasia more likely)

Bedside

• OGD: first investigation to exclude malignancy — oesophageal dilatation, retained food/fluid, puckered LOS that "pops" open; must biopsy GOJ

Bloods

• FBC: anaemia (nutritional deficiency)
• Albumin: nutritional status
• Trypanosoma cruzi serology: if travel to South America

Imaging

• Barium swallow: classic bird-beak appearance (smooth tapering at LOS), dilated oesophagus, absent peristalsis on fluoroscopy, air-fluid level
• CT thorax/abdomen: exclude GOJ mass (pseudo-achalasia), assess oesophageal dilatation

Special Tests

• High-resolution manometry (HRM): gold standard diagnostic test
  • Elevated integrated relaxation pressure (IRP) >15 mmHg
  • Absent peristalsis (100% failed swallows in Type I/II)
  • Chicago Classification v4.0 subtyping (I, II, III)
• Timed barium swallow: functional assessment; measures oesophageal emptying at 1, 2, and 5 minutes; useful for monitoring treatment response
• EndoFLIP (functional lumen imaging probe): measures distensibility of GOJ; increasingly used intra-operatively

Non-pharmacological

• Dietary advice: eat slowly, chew thoroughly, drink water with meals, eat upright, avoid eating before bed
• Elevate head of bed: reduce nocturnal aspiration risk

Pharmacological

• Medical therapy (bridge to definitive treatment or for those unfit for intervention):
  • Nifedipine 10-20 mg SL 30 minutes before meals (reduces LOS pressure by ~30%)
  • Isosorbide dinitrate 5-10 mg SL 15 minutes before meals
  • Sildenafil 50 mg (NO-mediated LOS relaxation — off-label)
• Medical therapy has limited long-term efficacy (~50% symptom improvement, diminishes over time)

Surgical/Interventional

• Pneumatic dilatation: graded balloon dilatation (Rigiflex 30 mm → 35 mm → 40 mm); ~85% initial success; perforation risk 2-5%; may need repeat dilatation
• Laparoscopic Heller myotomy + partial fundoplication (Dor anterior 180°): ~90% success; lower re-intervention rate than single dilatation; preferred for younger patients and Type III achalasia
• Peroral endoscopic myotomy (POEM): endoscopic alternative to Heller; ~90% success; higher rate of post-procedure GORD (up to 40-60%) as no fundoplication; increasingly popular
• Botulinum toxin injection (Botox 100 units into LOS): temporary relief (3-12 months); for patients unfit for dilatation/surgery
• Oesophagectomy: end-stage achalasia with megaoesophagus (>sigmoid oesophagus) not amenable to myotomy

Referral Criteria

• All suspected achalasia to gastroenterology for manometry
• Specialist oesophageal motility centre for definitive treatment
• Upper GI surgery for Heller myotomy or POEM
• Urgent investigation if pseudo-achalasia suspected

Both pneumatic dilatation and Heller myotomy provide good long-term symptom control in >80% at 5 years (European Achalasia Trial showed equivalence at 5 years). Type II achalasia has the best treatment response (~95%). Type III has the poorest response (~70%). POEM has excellent short-term results but higher GORD rates. Long-term achalasia is associated with a small increased risk of oesophageal squamous cell carcinoma (~3% lifetime risk) — some centres offer surveillance OGD every 3-5 years after 15 years of disease.

Chicago Classification v4.0 — Achalasia Subtypes

Treatment Comparison