Characteristics

• Achalasia or megaoesophagus is characterised by failure of organised peristalsis and relaxation of the lower oesophageal sphincter.

• Primary or idiopathic achalasia is due to degeneration of Auerbach's myenteric plexus.

• Rarely associated with infections, e.g. Chagas' disease (Trypanosoma cruzi) present in South American countries.

• Secondary or pseudoachalasia occurs due to malignant infiltration destroying the myenteric plexus from a fundal carcinoma or lymphoma.

• Oesophageal carcinoma occurs in 2–7% of patients with long-standing achalasia.

Clinical features

• Primarily a disease of early onset – aged 20–40 years.

• Long slow history of dysphagia, particularly to liquids.

• The dysphagia is posturally related. Swallowing improves in the upright position compared to lying prone. The increased hydrostatic forces allow transient opening of the lower oesophageal sphincter.

• Weight loss occurs in up to 90%.

• There is an increased risk of aspiration. Patients can present with chest infections or occult lung abscesses.

• Malignant transformation rarely occurs in long-standing cases and should be suspected with changes in symptoms, e.g. when painful dysphagia, anaemia or continued weight loss develop.

Radiological features

• CXR – an air-fluid level within the oesophagus may be present projected in the midline, usually in a retrosternal location, but can occur in the neck. Right convex opacity projected behind the right heart border, occasionally a left convex opacity can be demonstrated. Mottled food residue may be projected in the midline behind the sternum. Accompanying aspiration with patchy consolidation or abscess formation is demonstrated in the apical segment of the lower lobes and/or the apicoposterior segments of the upper lobe.

• Barium swallow – a dilated oesophagus beginning in the upper one-third. Absent primary peristalsis. Erratic tertiary contractions. ‘Bird beak’ smooth tapering at the gastro-oesophageal junction (GOJ) with delayed sudden opening at the GOJ. Numerous tertiary contractions can be present in a non-dilated early oesophageal achalasia (vigorous achalasia).