Achalasia is a relatively rare, progressive neurological disease which is characterised by difficulties in swallowing due to damaged nerves in the esophagus.

Achalasia has a lifetime prevalence of 1:10 000. It is a neurodegenerative disorder in which the neurons of the myenteric plexus are lost, leading to dysfunction of the lower esophageal sphincter and to a derangement of esophageal peristalsis. In the final stage of achalasia, esophageal motility is irreversibly impaired, and complications ensue because of the retention of food that is no longer transported into the stomach."

Source : Dtsch Arztebl Int. 109(12): 209–214

The disease, which was first reported in the medical literature in 1672, has unknown causes - but is widely believed to have a genetic component (details of which are also unknown.)

Because of its rarity, a correct diagnosis is frequently missed - which can significantly reduce chances of remedial treatment.