Median Arcuate Ligament Syndrome, also known as celiac artery compression syndrome or Dunbar syndrome, is a condition that occurs when the median arcuate ligament compresses, or squeezes, the celiac artery and the celiac plexus nerves.

To understand MALS, it is helpful to first understand the anatomy involved:

• The Diaphragm is the large, dome-shaped muscle at the base of the chest that controls breathing.
• The Aorta is the main artery that carries blood from the heart down through the abdomen.
• The Median Arcuate Ligament is a fibrous band of tissue that connects the left and right sides of the diaphragm. It forms an arch that passes over the aorta.
• The Celiac Artery is the very first major branch that comes off the aorta in the abdomen. It is a critical blood vessel that supplies oxygen-rich blood to the stomach, liver, spleen, and parts of the pancreas and small intestine.
• The Celiac Plexus (also called the celiac ganglion) is a complex network of autonomic nerves that surrounds the celiac artery. These nerves are involved in transmitting sensation, including pain, from the upper abdominal organs.

A helpful analogy is to think of the aorta as a major highway and the celiac artery as a critical exit ramp that supplies fuel to several important factories (the stomach, liver, and spleen).

• The median arcuate ligament is like a concrete overpass built across this exit ramp.
• For most people, the overpass is built high enough to allow all traffic to flow freely underneath without any issue.
• In MALS, this overpass was built too low, or the exit ramp comes off the highway at an abnormally high position.
• As a result, the ligament presses the exit ramp, creating a bottleneck. While this can sometimes restrict the fuel supply (blood flow) to the factories, it is now believed that the primary problem is that the overpass is also crushing the delicate electrical and communication cables (the celiac plexus nerves) that run alongside the ramp. It is this chronic nerve compression and irritation that is believed to cause the severe pain of MALS.

In my experience, MALS is one of the most commonly missed diagnoses in patients with chronic upper abdominal pain often labeled as functional or psychosomatic for years.

The cause of MALS is purely anatomical. The median arcuate ligament is simply positioned in a way that it physically compresses the celiac artery and its surrounding nerves. This is considered a congenital variation, meaning a person is born with this specific anatomical arrangement.

The great mystery of MALS is why some people with this anatomical compression develop severe symptoms, while many others with the exact same finding on a scan have no symptoms at all. It is estimated that the anatomical compression is present in 10-24% of the general population, but only a very small fraction of these individuals ever develop MALS (NORD, 2024). The reasons for this are not yet understood but may be related to the precise angle of the compression, the degree of nerve involvement, or other contributing factors.

I’ve noticed many patients are unaware this is a structural issue not caused by diet or lifestyle which makes their delayed diagnosis especially frustrating.

A person is born with an anatomical predisposition for MALS. It is not contagious, and it is not considered an inherited disease that runs in families in a predictable pattern. The symptoms, however, often do not appear until adolescence or young adulthood.

While the underlying anatomy is congenital, a specific event can sometimes trigger the onset of symptoms or make them worse. This can include:

• Abdominal surgery that alters the local anatomy.
• A significant abdominal injury.
• Significant weight loss that can reduce fatty tissue that cushions the artery and nerves.

MALS is diagnosed more frequently in women than men and is often seen in individuals who are thin.

Clinically, I’ve seen MALS diagnosed after extensive workups, often once other gastrointestinal causes have been ruled out especially in thin individuals with worsening pain after meals.

MALS is a “great imitator,” and its symptoms can often be mistaken for more common gastrointestinal disorders like gastritis, pancreatitis, or gallbladder disease. The symptoms are directly related to the compression of the artery and nerves, which is often made worse by the act of eating or by exercise.

The classic triad of symptoms includes:

1. Postprandial Abdominal Pain: This is the hallmark symptom. It is a chronic, often severe, cramping or burning pain in the upper middle part of the abdomen (the epigastrium). The pain consistently begins shortly after eating, typically within 15 to 30 minutes, as the digestive organs demand more blood flow.
2. Unintentional Weight Loss: This is a direct consequence of the postprandial pain. Individuals develop a “food fear” (sitophobia) because they know that eating will trigger their pain. They begin to eat smaller and smaller meals to avoid the symptoms, leading to significant weight loss.
3. Abdominal Bruit: A doctor listening to the abdomen with a stethoscope may hear a “whooshing” or “bruit” sound, which is caused by the sound of turbulent blood flowing through the narrowed celiac artery.

Other common signs and symptoms include:

• Nausea and vomiting, especially after eating.
• A feeling of bloating or being unable to finish a meal.
• Diarrhea.
• Abdominal pain can sometimes be worsened by exercise.

Clinically, I’ve seen that symptoms worsen with deep exhalation or after meals, and many patients also describe abdominal bruit or a sensation of pressure near the stomach.

The journey to a MALS diagnosis is often long and frustrating. Because the symptoms are non-specific, it is a diagnosis of exclusion. This means that a doctor must first perform a thorough evaluation to rule out all other, more common causes of upper abdominal pain. This workup typically includes an endoscopy, gallbladder ultrasound, gastric emptying study, and tests for pancreatitis, all of which will come back normal.

Once other conditions have been ruled out, a doctor who has a high index of suspicion will order specific tests to look for the celiac artery compression.

• Mesenteric Doppler Ultrasound: This is often the first specialized test. It is a non-invasive ultrasound that specifically measures the speed of blood flow through the celiac artery. The technologist will measure the velocity while the patient breathes in and then breathes out. A dramatic increase in the blood flow velocity during exhalation (when the diaphragm moves down and tightens the ligament) is the classic finding that suggests MALS.
• CT Angiography (CTA) or MR Angiography (MRA): These imaging scans provide a detailed, 3D map of the blood vessels. They can directly visualize the median arcuate ligament compressing the celiac artery, often showing a characteristic “hooked” appearance of the artery at its origin.
• Diagnostic Celiac Plexus Block: This is a crucial test to help confirm that the patient’s pain is actually coming from the compressed nerves. An interventional radiologist uses imaging guidance to inject a local anesthetic around the celiac plexus. If the patient experiences significant, temporary relief from their typical pain after the block, it provides strong evidence that the compression is the true cause of their symptoms and that they may be a good candidate for surgery.

Clinically, I rely on imaging studies like Doppler ultrasound, CTA, or MRA to visualize celiac artery compression especially looking for changes during respiration.

While some mild cases may be managed symptomatically, for individuals with classic MALS and significant weight loss, the definitive treatment is surgical. The goal of the surgery is to physically relieve the compression on the celiac artery and the surrounding nerves.

Median Arcuate Ligament Release

The standard procedure is a surgical division or cutting of the median arcuate ligament. By cutting this taut, fibrous band, the celiac artery and the celiac plexus are immediately freed from the compression.

• Surgical Approach: Today, this procedure is most often performed using minimally invasive techniques, such as laparoscopic or robotic surgery. The surgeon makes several small incisions in the abdomen and uses a camera and specialized instruments to visualize and carefully divide the ligament. This approach leads to a faster recovery compared to traditional open surgery.
• Ganglionectomy: During the same procedure, the surgeon will often also perform a celiac ganglionectomy, which involves removing the damaged and inflamed nerve tissue of the celiac plexus that has been chronically compressed. This is a critical step for ensuring long-term pain relief.

Prognosis

For well-selected patients who have the classic symptoms, a clear demonstration of compression on imaging, and significant pain relief from a diagnostic nerve block, the success rate of surgical ligament release is very high. Most individuals experience a complete or near-complete resolution of their abdominal pain and are able to eat normally again and regain their lost weight.

Clinically, I’ve found that some patients still experience pain postoperatively, suggesting a neuropathic component, so managing expectations and combining nerve block therapies is often necessary.

Median Arcuate Ligament Syndrome is a rare and often-missed cause of severe, chronic abdominal pain. For patients who suffer for years with debilitating pain after eating and are told that “all their tests are normal,” the condition can be physically and emotionally exhausting. It is a powerful reminder that an anatomical variation, while harmless in many, can be the source of real and significant suffering in others. While the path to a diagnosis can be a long journey of exclusion, the validation of finally identifying the physical cause of the pain is a critical turning point. Clinically, I’ve learned that early recognition and referral for proper imaging can prevent years of unnecessary tests, helping restore quality of life in carefully selected surgical candidates.

The National Pancreas Foundation. (n.d.). Median Arcuate Ligament Syndrome (MALS). Retrieved from https://pancreasfoundation.org/patient-information/median-arcuate-ligament-syndrome-mals/

The Cleveland Clinic. (2022). Median Arcuate Ligament Syndrome (MALS). Retrieved from https://my.clevelandclinic.org/health/diseases/16649-median-arcuate-ligament-syndrome-mals

National Organization for Rare Disorders (NORD). (2024). Median Arcuate Ligament Syndrome. Retrieved from https://rarediseases.org/rare-diseases/median-arcuate-ligament-syndrome/