Achalasia, also known as cardia spasm or megaesophagus, is a primary esophageal motility disorder characterized by lower esophageal sphincter relaxation disorder and substitute peristalsis. Its cause is not very clear, and there are three theories: congenital, myogenic and neurogenic. The neurogenic theory is currently widely accepted. The main clinical manifestations are difficulty in swallowing, food reflux and discomfort or pain behind the lower sternum. This disease is a rare disease (estimated to be only about 1 in every 100,000 people) that can occur at any age, but is most common in the age group of 20 to 39 years old. Children rarely get sick, and the incidence is roughly equal between men and women. It is more common in Europe and North America. If the disease is not treated in time, there is a potential risk of esophageal cancer.