Median Arcuate Ligament Syndrome

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MALS, which stands for Median Arcuate Ligament Syndrome, is a congenital anatomical anomaly. It is caused by the median arcuate ligament compressing the celiac artery and the nerves of the celiac plexus, which lead to the celiac ganglion. This can cause a change in blood flow and/or epigastric pain. It is found in 15%-34% of the US population, but only one percent of that number experience symptoms. 

MALS was first described as a medical condition by Dr. Harjola in 1963. Over the years, it has been known by other names, including Dunbar Syndrome and Celiac Artery Compression Syndrome. It has recently been listed on the Rare Disease Registry, and between 1963 and 2012, less than 500 corrective MALS surgeries were recorded in the English language. However, based on the current percentage estimates and the 2016 US population numbers, the statistical number of people with the MALS anatomy is 48.5 million to 11 million. Of those, half a million to 1.1 million will experience symptoms.

In a MALS patient, the diaphragm is located too low within his or her body, which lowers the median arcuate ligament. In a non-MALS patient, the ligament is located approximately four centimeters above the celiac artery. In a MALS patient, the ligament compresses the celiac artery and a bundle of nerves between the artery and ligament. This compression is present at the time of a patient’s birth, but symptoms often don’t develop until adolescence. MALS symptoms are most common among young women. 

The symptoms of MALS mimic gastrointestinal issues and may include upper-abdominal pain after eating, fatigue after eating, nausea and/or vomiting, constipation or diarrhea, exercise intolerance, and rapid weight loss. Unlike most gastrointestinal illnesses, MALS will not show up in blood work or in typical GI testing. Patients are often misdiagnosed with gallbladder issues, chronic abdominal pain, gastroparesis, eating disorders/food avoidance, and a myriad of other non-specific diagnoses. Patients may be given pain medications in an attempt to lessen their symptoms, and while this may work for a time, it does not solve the root problem.

MALS can only be treated with surgical intervention. However, there are currently only a few surgeons in the US who have experience in treating MALS, and procedures vary between each surgeon. Some surgeons use a laparoscopic approach to release the ligament, while others perform an open surgery and entirely remove the ligament and superficial layer of the celiac ganglion. It is important for patients and caretakers to thoroughly research treatment options to find the best surgeon and treatment plan for them. 

Most patients with chronic, undiagnosed abdominal pain have had many gastrointestinal tests performed, including EGDs, gastric emptying studies, colonoscopies, Bravo esophageal pH tests, CT scans, and ultrasounds. While these tests may not give patients the answers they’re looking for, they might still hold the answer that doctors aren’t looking for: MALS.

The two most common ways to diagnose MALS are an abdominal CT scan with contrast and a doppler ultrasound of the celiac artery. A CT scan provides a better look at the anatomy involved, while an ultrasound shows the blood-flow velocities. In order to spot MALS in either of these tests, skill is needed both on the part of the technicians performing the test and the radiologists and doctors who read them.

To find MALS on a CT scan, it is helpful (though not entirely necessary) for the patient to hold an exhale position, as it makes the characteristic “hook” shape of the celiac artery more apparent. If the image is taken while the patient inhales, it is possible for the hook to be less pronounced, which increases the likelihood of a missed diagnosis. This is why properly educated and trained technicians are so vital in the diagnosis of MALS. Another potential MALS indicator that can be seen on a CT scan is an abnormally low diaphragm. A low diaphragm increases the likelihood that the median arcuate ligament is too close to the celiac artery, causing the compression of the artery and/or the nerve bundle. 

Because a compression on the celiac artery can cause a change in blood flow velocities, a doppler ultrasound can also be used to diagnose MALS. The normal velocity through the celiac artery is 98-100 centimeters per second; stenosis (blockage) is suspected when velocities rise above 200 cm/sec. A stenosis can be indicative of a MALS diagnosis. However, as with a CT scan, ultrasounds require a skilled and educated technician who can properly instruct the patient on the necessary positions to hold as the ultrasound is being performed. Because of the increased difficulty in a MALS-specific ultrasound and the variations between techniques and technicians, ultrasounds may be a less conclusive diagnostic tool. 

Some patients do not experience a change in blood flow, though they still experience the pain associated with MALS due to nerve involvement. In neurogenic MALS, a celiac plexus block may be performed to determine if removal of the nerves will reduce a patient's symptoms.

Many patients have already had the testing necessary to diagnose MALS, though they and their doctors may be unaware--and yet most patients endure pain for years while wading through numerous tests and misdiagnoses. Raising awareness for this diagnosis is imperative if doctors hope to help patients restore their quality of life.

MALS is treated with surgical intervention. There are three primary surgical techniques: robotic-assisted, laparoscopic, and open. However, because MALS is a young diagnosis without much research, surgical procedures vary between surgeons. 

A robotic-assisted surgery is a laparoscopic procedure that gives surgeons more control, precision, and flexibility. Unfortunately, there is little literature on MALS-specific procedures, but this approach is used by some surgeons and is very similar to a conventional laparoscopic surgery.

To treat MALS laparoscopically, small incisions are made to allow surgical instruments access to the median arcuate ligament. The ligament is cut and trimmed to relieve compression on the celiac artery. In some cases, visible nerves may be removed. A laparoscopic surgery, being a minimally invasive procedure, may result in a shorter hospital stay. However, there is the potential that a laparoscopic approach may need to be converted to an open procedure if the aorta or celiac artery are nicked. 

The third and final surgical technique used to treat MALS is an open approach. An incision is made down the patient’s abdomen, allowing the surgeon complete access and visualization of the abdominal cavity. The surgeon is able to cut and trim the median arcuate ligament back to the spine, preventing regrowth of the ligament (which is actually a muscle, as it is part of the diaphragm). The damaged and inflamed nerves can be visualized and trimmed back to, and including, the superficial layer of the celiac ganglion. Because this is a more invasive surgery, both the recovery time and hospital stay are longer, but most patients are able to resume eating the day after surgery.

The type of surgery a patient undergoes is a personal choice, and one that should be highly researched, as additional surgeries increase the risks associated with treatment. Research is still necessary once a patient has decided on robotic-assisted, laparoscopic, or open surgery, because full procedures differ between surgeons. It is also wise to ask for a surgeon’s numbers--how many MALS surgeries he or she has performed, along with their success ratio--as there are some who have done one, and some who have done over one-hundred. Because of all this, it is important for patients and caretakers to research all of their options before deciding on a specific treatment plan.