What Is MALS?

Median arcuate ligament syndrome (MALS) is a rare condition in which the median arcuate ligament —located under the diaphragm in the abdomen—compresses the celiac artery. This impairs blood flow to the stomach, liver, and other organs, causing chronic abdominal pain that can occur with eating or exercise.

There's no one confirmed cause of MALS, though there are several accepted possibilities. MALS is difficult to diagnose and is only identified (with the help of imaging) when other possible causes of symptoms are ruled out. The only treatment for MALS is surgery to decompress the artery.

This article explains the causes, symptoms, diagnosis, and treatment of MALS, which is also known as:

• Celiac artery compression syndrome
• Celiac axis syndrome
• Harjola-Marable syndrome
• Dunbar syndrome
  

MALS Symptoms

Symptoms of MALS may include the following:

• Severe chronic upper abdominal pain that usually gets worse after eating
• Exercise-induced abdominal pain
• Unintentional weight loss (50% of patients)
• Nausea
• Vomiting
• Diarrhea
• Bloating
• Abdominal bruit, a distinct noise heard with a stethoscope when listening to the stomach (35% of patients; indicates a vascular blockage)

Rare symptoms include:

• Chest pain
• Constipation
• Difficulty sleeping

What Causes MALS?

The exact pathology of MALS is not well understood, but impaired blood flow may result in ischemia (poor oxygenation or even tissue death) in the stomach, liver, and other organs leading to pain.

Another theory is that compression of the celiac artery may also cause another blood vessel in the area called the superior mesenteric artery to increase blood flow to the stomach and liver after you eat. This is thought to cause abdominal pain.

MALS usually results in severe and chronic abdominal pain. But it is interesting that not all individuals with compression and even severely impaired blood flow of the celiac artery have symptoms. A group of nerves in the region called the celiac plexus may also be affected by MALS, and it may be the reason why this is so.

One hypothesis is that these nerves are overstimulated in people with symptomatic MALS and that this leads to a spasm of the arteries that supply blood to the stomach and small bowel. In this theory, these spasms are believed to be the cause of abdominal pain.

Yet another theory as to the cause of MALS is that the nerves in the area (the celiac plexus and peri-aortic ganglia) are actually compressed. This is may interfere with and cause hypersensitivity in the pain pathways connecting the brain and stomach.

It is likely that a combination of these factors results in the characteristic symptoms of MALS.

Diagnosis

Diagnosing MALS can be difficult since the symptoms overlap with that of many, many other conditions including GERD, gastroparesis, liver conditions, or gallbladder problems. MALS may also be misdiagnosed as an eating disorder, irritable bowel syndrome, or abdominal migraine.

Diagnosis of MALS is usually made by eliminating other diseases that cause these symptoms. This makes it what is known as a diagnosis of exclusion.

Individuals with MALS often undergo a significant number of medical tests before a diagnosis is made. Unfortunately, this also means they spend a lot of time having to cope with their symptoms.

Tests that are frequently used to rule out other conditions may include:

• Blood work
• Gastrointestinal imaging studies (such as abdominal ultrasound)
• Upper endoscopy with biopsy

When these tests fail to result in a diagnosis, three classic symptoms may lead your healthcare provider to consider MALS. They include:

• Unintentional weight loss
• Abdominal bruit
• Abdominal pain following meals

Once MALS is suspected, vascular imaging is necessary to confirm or rule out the diagnosis. A special type of ultrasound called a mesenteric duplex ultrasound helps to measure blood flow and is usually done first.

If a mesenteric duplex ultrasound performed during deep expiration suggests you might have MALS, follow-up tests such as a CT scan or MRI angiogram can help your healthcare provider to confirm this diagnosis.

Other tests that may be used include a gastric tonality test or a celiac plexus nerve block.

Celiac Plexus Nerve Block

A celiac plexus block involves the injection of a local anesthetic (via needle) into the celiac plexus nerve bundle.

The entire procedure takes about 30 minutes. You are typically given a light anesthetic type medication to help relax you and then asked to lie on your stomach. The skin of your back is numbed with a local anesthetic and then the healthcare provider (using an X-ray to see where to place the injections) injects the medication into the celiac plexus via your back near your spine.

If you experience pain relief after the nerves have been blocked this may be a good indication that you not only have MALS but also that you would benefit from corrective surgery.

Potential complications of a celiac plexus block are uncommon but may include:

• Bruising or pain at the site of the injections
• Reactions to the medication used (such as low blood pressure)
• Diarrhea
• Serious complications such as bleeding or nerve damage may occur but are very rare

You will need someone to drive you home after this procedure and should rest for a while since you've likely been given sedating medications that may impair your judgment, balance, or coordination. Most people can resume normal activities the day following a celiac plexus block. Pain relief should last a couple of days at least but everyone is different. You may experience longer-lasting pain relief the more times that you have this procedure.

MALS Treatment

Surgical decompression of the celiac artery is the only real treatment for MALS. However, not all people respond to this treatment.

Surgical Approaches

MALS surgery is performed both laparoscopically or using an open approach, depending on individual circumstances. It involves resecting the median arcuate ligament to relieve the pressure on the celiac artery and restore blood flow. At the same time, the nerve fibers of the celiac ganglion are divided to address the neurological component of MALS. Occasionally, a revascularization procedure of the celiac artery is performed at the same time.

A laparoscopic approach to MALS surgery is preferred as it is less invasive and usually results in shorter recovery time. Studies also suggest that a laparoscopic approach may result in better and faster relief of symptoms. Typically four or five small incisions are made in the abdomen through which the surgeon can work. Sometimes robotic assistance is used. Robotic assistance procedures showed high success rates in some studies.

Sometimes the surgeon may begin by using a laparoscopic approach but then convert to an open approach due to bleeding or other circumstances. The risk of bleeding for this particular procedure is approximately 9% and one advantage of using an open surgical approach is that it is easier to control a potential hemorrhage.

Due to the high risk of bleeding during MALS surgery there are often two surgeons working together during the procedure; one is usually a vascular surgeon. Death due to hemorrhage during this surgery was not reported in the studies used for this article. However, some patients did require blood transfusions. Verification of restored blood flow of the celiac artery is confirmed either during the surgery or immediately following.

Risks of Surgery for MALS

Potential complications of celiac artery decompression include:

• Hemorrhage and possible blood transfusions
• Incomplete celiac artery release
• Recurrence of symptoms following surgery
• Infection
• Complications of general anesthesia including malignant hyperthermia, difficulty breathing or even death
• Diarrhea, nausea, and self-limiting pancreatitis following surgery

Recovery

Following a celiac artery decompression, most patients remain in the hospital approximately two to three days.

Food is usually introduced right away. Individual recovery times vary greatly and may depend on what type of surgical approach your healthcare provider used. Patients who lost a significant amount of weight leading up to surgery may have nutritional deficits that need to be addressed. It is common to see your practitioner approximately four weeks following surgery for a follow-up.

Success of Treatment

Studies show that approximately 60% to 80% of patients who underwent celiac artery decompression experienced relief of their symptoms following surgery.

In general, you are more likely to achieve relief of your symptoms following surgery if:

• Your abdominal pain is associated with eating.
• You have not experienced periods of remission but your symptoms have been fairly constant since their onset.
• You have lost 20 pounds or more in weight.
• You are between 40 and 60 years old.
• You have not been diagnosed with a psychiatric disorder or alcohol abuse.
• You experienced a temporary relief of your symptoms following a celiac plexus nerve block.

For those who do not experience a relief of symptoms additional surgeries may be considered and may include:

• Open decompression of the celiac artery (if a laparoscopic approach was initially used and complete decompression was not achieved)
• Celiac stent placement
• Arterial bypass
• Angiography and angioplasty
• In some people celiac plexus nerve block may offer some relief of continued abdominal pain following decompression of the celiac artery

A small number of people do not experience symptom relief after a celiac artery decompression or even subsequent MALS surgical procedures. Better understanding of the pathology of MALS, including why a large number of people with significant celiac artery decompression never experience symptoms, is needed to improve the outcomes for all MALS patients.

A Word From Verywell

If you have MALS, you may feel a variety of emotions about your diagnosis and the potential for treatment success. It may help to read stories about others in your shoes and learn more about supportive resources.

The National MALS Foundation's website is a great place to start. You can also share your story in hopes of helping others.