- Achalasia refers to a functional obstruction of the esophagus resulting from failure of the Lower Esophageal Sphincter (LES) to relax appropriately as well as reduced peristalsis of the lower esophageal muscularis propria. Achalasia may arise from an underlying abnormality of the esophagus, referred to as "Primary Achalasia", or may be secondary to another defined disease process in which case it is referred to as "Secondary Achalasia".
- Primary Achalasia:
- Primary achalasia is thought to be due to loss of inhibitory neural innervation of the lower esophageal muscularis propria and LES. This results in increased resting tone and reduced dilation of the LES upon swallowing as well as reduced peristalsis of the lower esophagus.
- Secondary Achalasia:
- A number of diseases processes can result in secondary achalasia; however, infiltration of the lower esophagus with cancer cells such as those of gastric carcinoma can be a cause along with infection with Trypanosoma cruzi.
- Achalasia results in progressive esophageal dilation just above the LES. Food and fluids are often retained in the dilating esophagus and may result in food regurgitation and aspiration, especially nocturnally. Patients may display symptomatic chest pain and the course of the disease is often characterized by progressive dysphagia and weight loss. However, the most serious consequence of retained material is chronic esophagitis of the esophageal mucosa which increases the risk of esophageal carcinoma.