aetiology

Last edited 02/2022 and last reviewed 09/2023

Achalasia involves degeneration of the myenteric plexus and vagus nerve fibres of the lower oesophageal sphincter (1):

• neurological defect involving the ganglion cells of Auerbach's myenteric plexus in the lower oesophageal sphincter and oesophageal body
• abnormalities in the vagal dorsal motor nucleus, the nucleus ambiguous, and in the smooth muscle of the oesophagus.

The damaging agent has been variously hypothesised as a neurotoxic virus, an autoimmune process, and a genetic predisposition (1).

Secondary achalasia can be seen in:

• Chagas' disease caused by Trypanosoma cruzi
• gastric carcinoma that results in oesophageal infiltration
• eosinophilic gastroenteritis
• lymphoma
• neurodegenerative disorders
• viral infection

At its most severe, aperistalsis occurs in the lower two thirds of the oesophagus with normal peristalsis above it:

• food accumulates in the oesophagus which becomes dilated and atonic
• prolonged transit time may be a factor in the increased incidence of malignancy with achalasia - in up to 5% of cases.

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