Oesophageal achalasia is a rare swallowing disorder that makes it difficult for food and liquid to reach the stomach, causing discomfort and nutritional challenges for those affected.

Epidemiology

Oesophageal achalasia is not a common condition. It affects approximately one in every 100,000 people each year, with a prevalence of about 10 in 100,000 individuals worldwide^[3]. This means that roughly 3,000 cases are diagnosed annually in the United States alone^[14]. While achalasia is considered rare, recent studies suggest that the number of cases may be increasing. Over the past 16 years in the United States, there has been a notable rise in hospitalizations related to achalasia, with a disproportionate increase among patients under 65 years of age and racial minorities^[3].

The condition does not show a strong preference for any particular age group, race, or gender, though most people are diagnosed between the ages of 25 and 60^[2][6]. Children can develop achalasia as well, although this is less common. For reasons that are not yet fully understood, individuals with spinal cord injuries, particularly those affecting the cervical and thoracic vertebrae, appear to have a higher incidence of developing this disorder^[3].

Causes

The underlying cause of oesophageal achalasia remains largely unknown, but researchers believe it involves damage to or loss of nerve cells in the oesophagus. The condition is thought to occur when the myenteric plexus (a network of nerves) and vagus nerve fibres that control the lower oesophageal sphincter begin to degenerate^[3]. These nerves are essential for coordinating the muscle contractions that move food through the oesophagus and for allowing the valve at the bottom of the oesophagus to relax and open.

More specifically, there is a loss of inhibitory neurons that contain substances called vasoactive intestinal peptide (VIP) and nitric oxide synthase. These neurons normally help the muscles relax. In severe cases of achalasia, other types of nerve cells, called cholinergic neurons, may also be affected^[3]. Without these functioning nerve cells, the muscles in the oesophagus cannot work properly, leading to the symptoms of achalasia.

One theory suggests that achalasia may be an autoimmune disease triggered by a viral infection. In this scenario, the body’s immune system mistakenly attacks its own nerve cells in the oesophagus, causing them to slowly deteriorate and stop functioning properly^[2]. Other proposed explanations include genetic predisposition, meaning that some people may be born with a tendency to develop the condition^[3].

Most cases in the United States are classified as primary idiopathic achalasia, meaning the exact cause is unknown. However, secondary achalasia can occur due to other medical conditions. For example, Chagas disease, caused by the parasite Trypanosoma cruzi, can lead to similar symptoms. Other causes of secondary achalasia include gastric cancer infiltrating the oesophagus, eosinophilic gastroenteritis, lymphoma, certain viral infections, and neurodegenerative disorders^[3].

Risk Factors

Because the exact cause of achalasia is not fully understood, identifying specific risk factors is challenging. However, certain observations have been made about who might be more likely to develop the condition. While achalasia can affect anyone regardless of age, race, or gender, it is most commonly diagnosed in adults between the ages of 25 and 60^[2][6].

Individuals with spinal cord injuries appear to have an increased risk of developing achalasia, particularly those with damage to the cervical and thoracic portions of the spine^[3]. The reason for this connection is not yet clear. Additionally, people with anorexia nervosa may experience altered oesophageal motility similar to achalasia^[3].

There have been reports of achalasia developing after endoscopic sclerotherapy for varices, a procedure used to treat enlarged veins in the oesophagus. The higher the number of sclerotherapy sessions, the greater the potential risk^[3]. If there is a genetic component to achalasia, having a family member with the condition might increase risk, though this has not been definitively established.

Symptoms

The symptoms of oesophageal achalasia typically develop gradually and worsen over time. Many people live with mild to moderate symptoms for months or even years before seeking medical help or receiving a proper diagnosis. The most characteristic symptom is difficulty swallowing, known medically as dysphagia^[1]. This problem affects both solid foods and liquids, making eating and drinking increasingly challenging as the condition progresses.

When someone with achalasia tries to swallow, food and liquid do not move smoothly down the oesophagus to the stomach. Instead, they become stuck or backed up in the oesophagus. This can create a sensation of food lodged in the throat or chest^[5]. As a result, people with achalasia often bring back up undigested food or saliva into their mouth, a process called regurgitation^[1]. Sometimes this food has fermented while sitting in the oesophagus, giving it a bitter taste^[1].

Chest pain is another common symptom, and it can come and go. Some people experience severe chest pain, particularly after eating^[1][2]. This pain occurs because food is trapped in the oesophagus and cannot move into the stomach. Many people with achalasia also experience heartburn, though it is important to note that in achalasia, the discomfort comes from food trapped in the oesophagus rather than stomach acid backing up as in gastroesophageal reflux disease (GERD)^[1].

Other symptoms include belching, hiccups, and difficulty bringing up air from the stomach^[2]. Coughing at night is common, as food and liquid may travel back up the oesophagus while lying down^[1]. Because eating becomes difficult and uncomfortable, many people with achalasia experience significant, unexplained weight loss^[1][2]. In severe cases, individuals may develop malnutrition because they are unable to consume enough food^[2].

Prevention

Unfortunately, because the exact cause of oesophageal achalasia is not known, there are no proven methods to prevent the condition from developing. Since theories suggest it may involve autoimmune processes, viral infections, or genetic factors, there are no specific lifestyle changes, vaccinations, or supplements that can reduce the risk of developing achalasia^[1][3].

The best approach to managing achalasia is early detection and prompt treatment. If you experience persistent difficulty swallowing, unexplained weight loss, or frequent regurgitation of food, it is important to seek medical attention right away. Early diagnosis can help prevent complications and improve quality of life. Some people delay seeking help because they believe their symptoms are related to changing food preferences or simple indigestion, but any ongoing swallowing difficulties should be evaluated by a healthcare professional^[4].

While you cannot prevent achalasia itself, seeking treatment quickly can help prevent serious complications such as aspiration pneumonia, which occurs when food or liquid is inhaled into the lungs^[2]. Additionally, people with long-term, untreated achalasia have a small increased risk of developing oesophageal cancer, making regular follow-up care important^[4].

Pathophysiology

To understand how achalasia affects the body, it helps to know how swallowing normally works. The oesophagus is a muscular tube that runs from the mouth to the stomach. When you swallow, coordinated muscle contractions called peristalsis push food and liquid down the oesophagus^[2]. At the bottom of the oesophagus is a ring-shaped muscle called the lower oesophageal sphincter (LES). This valve normally stays closed to prevent stomach contents from backing up into the oesophagus. When food arrives, the sphincter relaxes and opens to allow the food to enter the stomach, then closes again^[2].

In achalasia, two major problems occur. First, the muscles in the oesophagus lose their ability to contract properly, meaning peristalsis either does not happen or does not work effectively^[3]. Second, and perhaps more significantly, the lower oesophageal sphincter fails to relax and open when food arrives. Instead, it stays tightly closed^[3]. In some cases, the sphincter may even be hypertensive, meaning it is under excessive pressure, though this occurs in less than half of patients^[3].

This combination creates a functional obstruction at the junction between the oesophagus and stomach^[3]. Food and liquid cannot pass through easily, so they accumulate in the oesophagus. Over time, the trapped food may ferment, producing the bitter taste that many patients experience when it comes back up^[1]. Without proper muscle contractions, only gravity can help move food down, and even then, the closed sphincter prevents it from entering the stomach^[2].

The fundamental problem lies in the nerve cells that control these muscles. The inhibitory neurons that contain vasoactive intestinal peptide (VIP) and nitric oxide synthase are essential for allowing the sphincter to relax. When these neurons degenerate or are lost, the balance between excitatory and inhibitory signals is disrupted, and the sphincter cannot perform its normal function^[3]. The progressive nature of the nerve damage explains why symptoms typically worsen over time.

As achalasia progresses without treatment, the oesophagus can become enlarged and may develop curves or bends. This further impairs its ability to move food toward the stomach^[5]. If food or liquid backs up into the windpipe, it can be inhaled into the lungs, leading to complications such as aspiration pneumonia, bronchiectasis, and lung infections^[2]. The chronic inability to eat and maintain proper nutrition can lead to significant weight loss and malnutrition^[2].