Achalasia is a rare condition where the movement of food through the esophagus and into the stomach is impaired due to failure of some of the esophageal muscles to relax. The lower esophageal sphincter (LES) which is a ring of muscles that control the passage of food between the esophagus and stomach are hypertonic meaning that it it remains contracted. Achalasia is an esophageal motility disorder in that the coordinated movement of foods through the esophagus (gullet) is impaired.
How does achalasia work?
When food enters the esophagus, a series of coordinated muscle contractions known as the peristaltic wave pushes food down the esophagus. At the end of the of the esophagus, the LES (also known as the cardiac sphincter) should open and allow food to enter the stomach. The LES is an important structure that prevents the stomach (gastric) contents from emptying into the esophagus and causing damage due to gastric acid.
With achalasia, the peristaltic wave is disrupted and the LES does not relax and open. With time, the body of the esophagus becomes progressively dilated and this appears as a balloon-like esophagus (gullet) with a stricture at the bottom (LES) which can be seen upon conducting a barium swallow x-ray (refer to the picture below).
The cause of achalasia is unknown but certain findings have provided some answers as to how it occurs. There seems to be a defective release of nitric oxide by nerve cells that should prompt the LES to relax (inhibitory neurons). There also appears to be a degeneration of the myenteric plexus which innervates the esophagus. This indicates the the nerves signals to the muscles of the esophagus are impaired and cannot coordinate the opening and closing of the LES.
What are the signs and symptoms of achalasia?
The most common symptom reported by achalasia patients is dysphagia (difficulty swallowing). This develops gradually and may only be noticed when consuming solid foods. In the early stages of achalasia, dysphagia may not be constant but rather occurs in episodes that passes on its own. Some patients initially report the symptoms as indigestion which eases after walking or standing up.
Regurgitation of food is a common feature as well as gagging. As the condition progresses, there is pulmonary aspiration where the esophageal contents enter the airways. This more frequently occurs at night (nocturnal) and may cause the patient to wake up coughing with a choking sensation. Aspiration can eventually lead to a host of respiratory symptoms and conditions.
There is a sensation of pressure in the chest just behind the breastbone (retrosternal) which may sometimes be described as heartburn although it is not due to acid reflux. Esophageal spasms result in chest pain. As the condition progresses, the patient may only eat semi-solid foods or drink liquids for nourishment. Loss of weight is eventually seen in most achalasia patients.