Achalasia (primary achalasia) is a failure of organised oesophageal peristalsis causing impaired relaxation of the lower oesophageal sphincter, and resulting in food stasis and often marked dilatation of the oesophagus.
Obstruction of the distal oesophagus from other non-functional aetiologies, notably malignancy, may have a similar presentation and have been termed "secondary achalasia" or "pseudoachalasia".
Primary achalasia is most frequently seen in middle and late adulthood (age 30 to 70 years) with no gender predilection 6. Most cases are idiopathic; however, a similar appearance may occur in Chagas disease. Authors differ as to whether to reserve the term achalasia for idiopathic cases or to include Chagas disease.
Patients typically present with
- dysphagia for both solids and liquids: this is in contradistinction to dysphagia for solids only in cases of oesophageal carcinoma 7
- chest pain/discomfort
- eventual regurgitation
Symptoms are initially intermittent. Patients may also present with complications of long-standing achalasia:
- the most dreaded complication, seen in approximately 5%, most often in the mid-oesophagus
- thought to occur because of chronic irritation of the mucosa by stasis of food and secretions
- aspiration pneumonia: the chronic presence of fluid debris in the oesophagus makes patients very prone to aspiration
- candida oesophagitis
- acute airway obstruction: this is a rare complication requiring immediate oesophageal decompression with a nasogastric tube
Peristalsis in the distal smooth muscle segment of the oesophagus may be lost due to an abnormality of the Auerbach plexus (responsible for smooth muscle relaxation), resulting in weak, uncoordinated contractions that are non-propulsive. The abnormality may also occur in the vagus nerve or its dorsal motor nucleus.
The lower oesophageal sphincter eventually fails to relax, either partially or completely, with elevated pressures demonstrated manometrically 4. Early in the course of achalasia, the lower oesophageal sphincter tone may be normal or changes may be subtle.
Achalasia characteristically involves a short segment (less than 3.5 cm in length) of the distal oesophagus.
Chest radiograph findings include:
- convex opacity overlapping the right mediastinum. Occasionally may present as a left convex opacity if the thoracic aorta is tortuous.
- air-fluid level due to stasis in a thoracic oesophagus filled with retained secretions and food
- small or absent gastric bubble
- anterior displacement and bowing of the trachea on the lateral view
- patchy alveolar opacities, usually bilateral, may be seen. These represent acute pneumonitis or chronic aspiration pneumonia related to dysphagia.
Fluoroscopy with barium swallow
A barium swallow study may be used to confirm oesophagus dilatation, in addition to assessing for mucosal abnormalities.
- bird beak sign
- oesophageal dilatation
- tram track appearance: central longitudinal lucency bounded by barium on both sides 8
- incomplete lower oesophageal sphincter relaxation that is not coordinated with oesophageal contraction
- pooling or stasis of barium in the oesophagus when the oesophagus has become atonic or non-contractile (a late feature in the disease)
- uncoordinated, non-propulsive, tertiary contractions (see case 1)
- failure of normal peristalsis to clear the oesophagus of barium when the patient is in the recumbent position, with no primary waves identified
- when the barium column is high enough (with the patient standing), the hydrostatic pressure can overcome the lower oesophageal sphincter pressure, allowing passage of oesophageal content
- a hot or carbonated drink during the exam may help visualise sphincter relaxation and barium emptying
Patients with uncomplicated achalasia demonstrate a dilated, thin-walled oesophagus filled with fluid/food debris.
Overall, CT has little role in directly assessing patients with achalasia, but is useful in assessing common complications. Careful assessment of the wall of the oesophagus should be undertaken to identify any focal regions of thickening which may indicate malignancy. The lungs should be inspected for evidence of aspiration.
Treatment and prognosis
Treatment is aimed at allowing adequate drainage of the oesophagus into the stomach. Options include 4,5:
- lifestyle changes
- eating slowly, increasing water intake with meals, avoiding eating near bedtime
- avoiding foods that aggravate reflux
- calcium channel blockers
- ineffective in the long term
- may be used while preparing for definitive treatment
- pneumatic dilatation
- effective in 85% of patients
- 3-5% risk of bleeding/perforation
- botulinum toxin injection
- lasts only ~12 months per treatment
- may scar the submucosa leading to increased risk of perforation during subsequent myotomy
surgical myotomy (e.g. Heller myotomy)
- 10-30% of patients develop gastro-oesophageal reflux, and thus it is often combined with a fundoplication (e.g. Dor, Toupet, Nissen)
- peroral oesophageal myotomy (POEM procedure) is a newer minimally-invasive technique which may be used in select patients
History and etymology
The word achalasia stems from the Ancient Greek term for "does not relax".
A number of entities may mimic achalasia, forming the so-called 'achalasia pattern'.
- achalasia: the distal segment of narrowing is <3.5 cm
- central and peripheral neuropathy
- scleroderma: gastro-oesophageal junction (GOJ) will be open; less severe dilatation
- oesophageal malignancy or gastric carcinoma: commonly referred as pseudoachalasia
- oesophageal stricture
- Chagas disease
- anti-Hu antibodies from lung cancer (paraneoplastic syndrome)
Other oesophageal disorders should also be considered:
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- oesophageal dysmotility
- oesophageal tumours
- benign oesophageal neoplasms
- malignant oesophageal neoplasms
- gastro-oesophageal reflux disease
- oesophageal stricture