Achalasia is a disorder benign esophageal motor, which is characterized by failure to relax the lower esophageal sphincter ( LES) in response to swallowing associated with lack of peristalsis of the esophageal body . Its most common clinical presentation is dysphagia , and occasionally chest pain , regurgitation , aspiration pneumonia and weight loss , resulting in a large impact on daily activities and quality of life of affected individuals .