Achalasia is a rare condition that affects the oesophagus that connects the throat to the stomach. The nerves in the oesophagus no longer signals it to push food down into the stomach, and the valve at the end of the oesophagus (lower oesophageal sphincter) no longer opens during swallowing. As a result, ingested food cannot enter the stomach and collects in the oesophagus. It is a progressive disease that worsens over time and results in a higher risk of oesophageal cancer.
The majority of achalasia cases are idiopathic (i.e. unknown cause). No one truly knows why the nerve cells in the oesophagus are affected, although it has been linked to virus infections or autoimmune disease (where the nerves are “attacked” by your own immune system).