MALS (Median Arcuate Ligament Syndrome)

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, impairing blood flow to the stomach, liver, and other organs. It causes chronic abdominal pain, which can occur with eating or exercise. MALS is also called celiac artery compression syndrome, celiac axis syndrome, Harjola-Marable syndrome, or Dunbar syndrome.

Causes

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 and that this actually causes abdominal pain.

A group of nerves in the region, called the celiac plexus may also be affected. MALS usually results in severe and chronic abdominal pain. It is interesting that not all individuals with compression and even severely impaired blood flow of the celiac artery have symptoms. This may indicate that the celiac plexus plays a big role in this condition. 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 and that these spasms are 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 and that this interferes with and causes 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.

Median arcuate ligament syndrome may affect both men and women of all ages but most often seems to affect young women between the ages of 30 to 50. It is approximately four times more likely to occur in women than in men.

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, this is present in about 35% of patients and indicates a vascular blockage)
Rare symptoms include chest pain, constipation or difficulty sleeping

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, (called a diagnosis of exclusion), so individuals with MALS have often undergone a significant number of medical tests before a diagnosis is made and have spent a significant amount of time suffering from their symptoms.

Tests that are frequently used to rule out other conditions may include blood work, gastrointestinal imaging studies (such as abdominal ultrasound), and upper endoscopy with biopsy,

When these tests fail to result in a diagnosis, the three classic symptoms of unintentional weight loss, abdominal bruit, and abdominal pain following meals may lead your doctor to consider MALS. 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 that helps to measure blood flow is usually the first place to start.

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 doctor 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 doctor (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.

The pain relief experienced from a celiac plexus block is temporary. For longer or more permanent relief a series of injections may be given and alcohol or phenol may be used to destroy the nerves.

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.

Treatment of MALS

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

This 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 this 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 there are often two surgeons, (one is usually a vascular surgeon), working together during the procedure. 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.

Potential complications of celiac artery compression 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
Some patients reported diarrhea, nausea, and self-limiting pancreatitis following surgery

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 doctor 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 doctor approximately four weeks following surgery for a follow-up.

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