Median Arcuate Ligament Syndrome (MALS)
What is median arcuate ligament syndrome?
Median arcuate ligament syndrome (MALS) is a condition in which the median arcuate ligament presses too tightly on the celiac artery (a major branch of the aorta that delivers blood to the stomach, liver, and other organs) and the nerves in the area (celiac plexus).
Ligaments are bands of tissue that connect one bone or cartilage to another. The median arcuate ligament is shaped like an arch and goes around the aorta (the artery in the heart that carries blood throughout the body) to connect the diaphragm to the spine.
In a person with MALS, the median arcuate ligament essentially acts like a hammer and the celiac axis acts like an anvil, compressing the take off of major vessels and squeezing nerves in between. (The “take off” is the spot where the celiac axis divides into three branches — the hepatic, left gastric and splenic arteries.) By compressing the artery right before it branches, MAL cuts off blood supply to the stomach and liver. This is a reason why patients complain of pain after meals.
Median arcuate ligament syndrome (MALS) is different than median arcuate ligament compression. Median arcuate ligament compression occurs in about 10% to 25% of the population and doesn’t cause any symptoms. In a very small number of these individuals, MALS is present, and healthcare provider with it will have the symptoms listed below.
Who is likely to have median arcuate ligament syndrome (MALS)?
MALS occurs most often in thin, younger women. It is a very rare condition.
Symptoms and Causes
What are the signs and symptoms of median arcuate ligament syndrome (MALS)?
The first sign of MALS is pain in the upper abdomen after eating. The pain causes you to avoid eating (called food aversion), which leads to weight loss (often more than 20 pounds). Other associated symptoms may include:
- Delayed gastric emptying (a delay in food moving from the stomach into the small intestine).
What causes median arcuate ligament syndrome (MALS)?
It’s believed that MALS is caused by the median arcuate ligament compressing, or pinching the celiac plexus nerves over the celiac artery. The squeezing of these nerves can cause a pain similar to the pain you feel in your hands if you have carpal tunnel syndrome feel in their hands. Another cause of the condition may be the lack of blood flow to the organs supplied by the celiac artery, though this theory is controversial.
Diagnosis and Tests
How is median arcuate ligament syndrome (MALS) diagnosed?
If your healthcare provider thinks you may have MALS, they’ll review your medical history and perform a physical examination. Your provider may also order certain tests, including blood work and imaging tests, to help rule out more common causes of your symptoms. These include:
- Gastroesophageal reflux disease (GERD).
- Problems with your pancreas, liver, gallbladder, spleen or intestines.
Once these conditions are ruled out, your healthcare provider may order a test called a mesenteric duplex ultrasound to check blood flow through the celiac artery and compression of the celiac plexus. Another helpful imaging test would be a CT or MRI angiogram, which can give a better picture of your celiac artery and aorta.
Once the diagnosis of MALS is suspected, your records will be reviewed and these steps followed.
- Imaging tests will be repeated or ordered (such as a mesenteric ultrasound of the celiac axis or a CT/MRI angiogram).
- You’ll consult with surgeons in the minimally-invasive surgery field and/or vascular surgery.
- You’ll be evaluated by a pain management specialist for a potential celiac plexus block procedure. This offers temporary relief from the symptoms of MALS, and helps to confirm the diagnosis.
Management and Treatment
How is median arcuate ligament syndrome (MALS) treated?
Once the diagnosis of MALS is confirmed, it is likely that your provider will suggest a minimally invasive (laparoscopic/robotic) approach to relieving the compression of the median arcuate ligament on the aorta. In this technique, the surgeon makes five to six small (approximately 1/2 inch) incisions (cuts) and inserts instruments to separate the median arcuate ligament and divide the nerves (neurolysis).
Most people who have laparoscopic surgery for MALS stay overnight in the hospital and begin eating a normal diet the next morning. You’ll have some discomfort and pain from the incisions, and will receive medications to relieve the pain. Most people with the condition say that their MALS symptoms, such as pain with eating, improve after the surgery. You should probably be able to return to normal activities within two weeks.
About 10% of people with MALS have a traditional “open” operation. Your surgeon, often with the assistance of a vascular surgeon, will make a large incision down the middle of the abdomen. If you have this procedure, you may need to stay in the hospital for three to five days to recover. You can usually return to normal activities within four to six weeks.
What is a celiac plexus block?
A celiac plexus block is an injection of medication to help relieve pain in the abdomen.
If you have a celiac plexus block, you’ll be given an intravenous medication to relax you. Then you will lie on your stomach on an X-ray table. The healthcare provider will numb an area of skin on your back with a local anesthetic. Then, guided by an X-ray, the healthcare provider will:
- Insert a thin needle into your back, next to your spine, and inject an anesthetic.
- Insert a second needle on the other side of your spine.
- Inject dye to make sure the medication goes to the correct spot.
- Inject pain medication, such as epinephrine, clonidine, or a steroid. Alcohol or phenol also may be injected to destroy the nerves.
The procedure usually takes less than 30 minutes, and you can go home the same day. Your abdomen may feel warm, and you may begin to feel less abdominal pain.
You’ll usually need a series of injections (between two and 10) to continue the pain relief. For some people, a celiac plexus block can relieve pain for weeks. For others, the relief can last for years. Many can return to their normal activities.
Outlook / Prognosis
What type of follow-up care is needed after median arcuate ligament syndrome (MALS) surgery?
Most people who have MALS have a duplex ultrasound one month after surgery to make sure that there is no further compression of the median arcuate ligament. Some people continue to have narrowing of the celiac artery because of scar tissue that has built up. This usually doesn’t cause symptoms after surgery and can be treated with non-surgical techniques such as medications or, rarely, another celiac plexus block. Occasionally, other endovascular therapies such as stenting of the celiac axis may be needed.
A small group of people who have repeated episodes of MALS may be candidates for a second attempt at the release of the scar tissue. These individuals, however, are at much higher risk (greater than 50%) of needing an open operation (with the assistance of a vascular surgeon).