Achalasia (primary achalasia) is a failure of organised oesophageal peristalsis that causes impaired relaxation of the lower oesophageal sphincter, 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 has been termed "secondary achalasia" or "pseudoachalasia".
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Epidemiology
Primary achalasia is most frequently seen in middle and late adulthood (age 30 to 70) 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 include Chagas disease. Patients with Allgrove syndrome (triple A syndrome) also have achalasia, which is very similar to the primary form of the disease.
Diagnosis
The Chicago Classification v4.0 defines achalasia as 100% absent peristalsis on manometry (either failed peristalsis or premature contracture, depending on the subtype) 16.
Clinical presentation
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:
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the most dreaded complication, seen in ~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
acute airway obstruction: this is a rare complication requiring immediate oesophageal decompression with a nasogastric tube
The Eckhardt score can be used to grade the clinical severity of achalasia.
Pathology
The lower oesophageal sphincter fails to relax, partially or completely, with elevated pressures demonstrated manometrically 4. This appears to be due to the loss/destruction of neurones in the Auerbach/myenteric plexus. Early in the course of achalasia, the lower oesophageal sphincter tone may be normal, or changes may be subtle.
Peristalsis in the distal smooth muscle segment of the oesophagus is eventually lost due to a combination of damage to the Auerbach plexus and vagus nerve (possibly partly due to damage at the dorsal motor nucleus of the vagus nerve).
Classification
Achalasia may be divided into three distinct subtypes based on manometric patterns per the Chicago Classification v4.0 (c. 2021) 16:
type I (classic achalasia): minimal contractility in the oesophageal body
type II: intermittent periods of pan-oesophageal pressurisation
type III (spastic achalasia): premature or spastic distal oesophageal contractions
Radiographic features
Achalasia characteristically involves a short segment (less than 3.5 cm in length) of the distal oesophagus.
Plain radiograph
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
Barium swallow
A barium swallow study may be used to confirm oesophageal dilatation and assess for mucosal abnormalities.
Findings include:
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
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
Ultrasound
Smooth narrowing at oesophago-gastric junction and proximal dilated oesophagus can be seen. It can also be useful to rule out possibility of any malignant mass in the region.
CT
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 oesophagus wall 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 4,5,11:
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lifestyle changes
eating slowly, increasing water intake with meals, avoiding eating near bedtime
avoiding foods that aggravate gastro-oesophageal reflux
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calcium channel blockers
ineffective in the long term
may be used while preparing for definitive treatment
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pneumatic dilatation
effective in up to 90% of patients
3-5% risk of bleeding/perforation
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botulinum toxin injection
lasts only ~12 months per treatment
may scar the submucosa, leading to an increased risk of perforation during subsequent myotomy
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surgical myotomy (e.g. Heller myotomy)
effective in up to 96% of patients
peroral oesophageal myotomy (POEM procedure) is a newer minimally-invasive technique which may be used in select patients
10-30% of patients develop gastro-oesophageal reflux, and thus, it is often combined with a fundoplication (e.g. Dor, Toupet, Nissen)
There is a variable response to treatment following endoscopic or surgical myotomy based on which achalasia subtype is present 11:
type I: intermediate prognosis (81%) inversely associated with the degree of oesophageal dilatation
type II: very favourable prognosis (96%) 14
type III: less favourable outcomes (66%)
History and etymology
The word achalasia stems from the Ancient Greek term for "does not relax".
Differential diagnosis
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 to as pseudoachalasia
Chagas disease: achalasia with neurenteric plexus damage due to Trypanosoma cruzi infection
anti-Hu antibodies from lung cancer (paraneoplastic syndrome)
Other oesophageal disorders should also be considered:
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