Achalasia is the best known primary motility disorder of the esophagus. It is characterized by failure of esophageal body peristalsis and incomplete relaxation of the lower esophageal valve. The abnormalities is caused by degeneration of some of the nerves of the lower part of the esophageal wall which causes loss of the ability to swallow food properly at the lower end of the esophagus. The cause of the condition is not entirely understood. Patients with this condition have difficulty swallowing or dysphagia and most of them have regurgitation of food contents. Sometimes this condition can cause respiratory symptoms because the contents that are regurgitated up the esophagus go down into the airway passages and then cause pneumonia.

These patients also often have endoscopy which reveals residual liquid or food in the esophagus. In order to definitively establish the diagnosis of achalasia, manometry pressure measurements of the esophagus is carried out and demonstrates that there is an elevated pressure at the lower end of the esophagus and incomplete relaxation of the valve. Treatment of this condition is either by balloon dilatation or surgery or Endoscopic myotomy. Use of a Botulinum toxin has been used the treatment of achalasia; however, patients that respond to this treatment often get recurrences.