Last updated:
7/18/2025
Years published: 2019, 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, Christopher L. Skelly, MD, Elizabeth Townsend, and Grace Z. Mak, MD, University of Chicago, Department of Surgery, for the preparation of this report.
The median arcuate ligament syndrome (MALS) is a is a rare condition where the median arcuate ligament, a band of tissue under the diaphragm, compresses the celiac artery and surrounding nerves leading to chronic abdominal pain.1,2 The compression of the celiac artery and/or the celiac plexus nerves by the diaphragm can result in pain that is worsened with eating or sometimes with exercise. Other symptoms include nausea and weight loss. In some people the symptoms can be devastating and can lead to incorrect diagnoses of an eating disorder, psychiatric conditions, or functional abdominal pain (e.g. irritable bowel syndrome, abdominal migraine).1,2,3 This condition affects both children and adults.4,5 The diagnosis is made based on a combination of the clinical symptoms and radiology imaging.1, 6,7,8.9 Treatment may include a surgical procedure that is effective in approximately 60-80% of patients.3
The signs and symptoms of the median arcuate ligament syndrome result from the compression of the celiac artery and the surrounding nerves. The common signs and symptoms may include:1,2,3,10
· Upper abdominal pain (frequently made worse with eating)
· Weight loss
· Nausea
· Vomiting
Sometimes a doctor may hear a soft whooshing sound with a stethoscope (bruit) over the upper abdomen that may mean there is a vascular blockage. Some people with this condition and who are athletes may experience recurrent upper abdominal pain that is brought on by moderate to intense cardiovascular workouts.
Additional symptoms associated with the diagnosis, but frequently indicative of other medical problems include palpitations (hearing or feeling the own heartbeat), chest pain, diarrhea, constipation and difficulty sleeping.
Chronic abdominal pain is a very common condition that can have significant negative, long-term psychosocial consequences, including increased risk for anxiety, school and work absences, poor functional capacity and a poor quality of life.7,9
The median arcuate ligament is a band of tissue formed where the two sides of the diaphragm meet and wrap around the aorta as it moves from the chest into the abdomen. Its anatomic relationship to the celiac artery origin dictates whether compression occurs. If the celiac artery arises above the diaphragm, the ligament can compress it; if it branches below, compression does not occur.4
In one anatomical study of 75 adults, the ligament completely crossed over the origin of the celiac artery in about one-third of cases, and partially in nearly half, leading to significant compression in most individuals.4
Even though studies show that between 13% and 50% of healthy people, who have no digestive complaints, have some degree of celiac artery compression, only a small number develop symptoms of median arcuate ligament syndrome (MALS).5
This has led to ongoing debate among physicians about whether MALS truly exists as a distinct condition, what exactly causes the symptoms and how best to treat it. The discomfort experienced in MALS may result from two main factors or a combination of both: 1,2,6,9
Traditionally, surgeons believed that chronic digestive discomfort from poor blood flow only occurred when two out of three main abdominal arteries were blocked. However, many specialists now recognize that symptoms can arise from a combination of vascular (blood-flow) and neurologic (nerve-related) factors, even if only one vessel is affected.
Median arcuate ligament syndrome affects approximately 2 per 100,000 people.1 The characteristic MALS patient is more likely to be young adult female, which is consistent with demographic characteristics of other chronic abdominal pain (CAP) patients. However, given the wide distribution of celiac artery compression, the syndrome affects both young and old as well as females and males.
The combination of upper abdominal pain and the finding of celiac artery compression on radiologic studies suggests the diagnosis of the MALS. However, the challenge with celiac artery compression is that about 13%-50% of people (13-50%) with radiographic features of celiac artery compression do not have any symptoms. This has led to controversy regarding the existence and management of this syndrome.
Because there are many people with celiac artery compression who do not have any symptoms, and because there are many causes for abdominal pain, it is important to have a detailed evaluation for all possible common causes of abdominal pain before being diagnosed with MALS.
There has been very little published with specific protocols for diagnosis of MALS. Because celiac artery compression syndrome is defined by ruling out other causes (diagnosis of exclusion), the evaluation typically relies on basic tests designed to eliminate alternative diagnoses. Complete medical evaluation should include blood work (complete blood count, chemistry panel, liver function tests, amylase, lipase, inflammation markers, erythrocyte sedimentation rate, C-reactive protein, pre-albumin, thyroid function tests) upper gastrointestinal imaging studies, small bowel follow-through, abdominal ultrasound, upper endoscopy with biopsy and evaluation for inflammatory bowel disease and celiac disease.
Screening should be done with a mesenteric duplex ultrasound. Positive findings demonstrate elevated blood flow velocities (PSV=peak systolic velocity) in the celiac artery greater than 200 cm/sec and an end diastolic velocity (EDV) greater than 55 cm/sec. Further demonstration of a decrease or even normalization of the velocities with deep inspiration is suggestive of celiac artery compression. Patients then undergo CT (computerized tomography) scan, MRA (magnetic resonance angiogram) or sometimes an angiogram to confirm the change in the shape of the celiac artery in both inspiratory and expiratory phases.7
Once other common causes of pain have been excluded and celiac artery compression is confirmed, it is essential to have an evaluation to determine if surgery is appropriate. Patient characteristics reported to be predictive of successful outcomes following surgery include consistent abdominal pain after eating, ages between 40-60 years and weight loss of 20 pounds or greater. Surgery tends to not be helpful in people in which the pain is atypical, when there are periods of remission, in people over the age of 60 years, when there is a history of alcohol abuse, and weight loss of less than 20 pounds.7, 11,12,13,14
Treatment
People with MALS often need to be evaluated by several specialists who should work together as a team. Management begins with a multidisciplinary evaluation, involving vascular surgery, general surgery, pain specialists and interventional radiology. A celiac plexus block, injection of local anesthetic or neurolytic agent into the nerve bundle under imaging guidance, can serve both to relieve pain temporarily and to confirm the diagnosis. People who experience transient relief are more likely to benefit from surgery.1,2,3
Additionally, it has been recommended to incorporate psychiatric and chronic pain services in the pre-operative and post-operative evaluations given the correlation between chronic physical pain and psychological pain. Pre-operatively, there should be evaluation by a multi-disciplinary team consisting of general and vascular surgery, psychiatry and pain service. Surgery should not be considered until the patient has been unanimously cleared by the entire team.7 8,9,15
The standard treatment of celiac artery compression syndrome is surgical release of the celiac artery from compression with simultaneous removal of the nerves that are being compressed as well. Three main approaches are used including open, laparoscopic and robotic, and all have been shown to be safe and effective, with no clear evidence that one technique is superior to the others.6,16,17
Basically, during the surgery, the median arcuate ligament is cut along with any overlying soft tissues and lymph nodes to relieve pressure on the artery. In some people, parts of the nearby nerve bundle (celiac plexus) are also removed. To confirm success, some teams use ultrasound during the operation, while others look for a visible change in the artery’s shape.6,16,17,18
Compared with open surgery, laparoscopic release typically offers less postoperative pain, shorter hospital stays, faster recovery, and better cosmetic results.3 Robotic assistance can enhance precision and three-dimensional visualization but may increase cost, require larger ports and limit tactile feedback.3
It is not recommended to perform endovascular stenting of the celiac artery before the surgery, as these stents generally fail due to external compression from the median arcuate ligament.6,16,17
After decompression, angioplasty or stenting may be considered in cases of persistent narrowing. Antiplatelet and cholesterol-lowering medications are only indicated when revascularization is performed.2
Most people report significant pain relief after release surgery, with 60%–80% becoming symptom-free.1,16,17 Minor complications such as diarrhea, nausea and transient pancreatitis are generally self-limited.1, 11,12
A major concern is ongoing or recurrent abdominal pain. Persistent pain often reflects either residual vascular narrowing or functional (non-vascular) pain, reinforcing the need for re-evaluation.1,11,12 Surgery does not address coexisting anxiety or depression, which can influence recovery.
If the pain continues or comes back, doctors may need to re-check blood flow to look for new narrowing from scar tissue or natural anatomy, often with an ultrasound. A balloon angioplasty may be considered to widen the artery if high flow speeds and breathing-related changes are seen on ultrasound. If blood flow looks normal, a CT angiogram can be done to rule out other abdominal issues. If imaging is clear, a celiac plexus nerve block is offered to address the possibility of functional abdominal pain (pain without a vascular cause).1,2,7
There is ongoing debate about why celiac artery compression causes pain: 6,8,11,19-22
Some experts point to reduced blood supply (ischemia) and enlargement or irritation of the nerve fibers. Under the microscope, changes such as thickening of the artery wall and disorganization of its layers have been noted.11 It was once thought that gut pain only occurred when two of the three main abdominal arteries were affected. Today, most agree that multiple factors including nerve-related elements contribute to symptoms.6,8,11,21
Because many people have compression on scans without any pain, and not everyone improves after surgery, it is suggested that there may be other factors.9,15,21
Rigorous trials comparing surgery to non-operative care or sham procedures would help clarify who truly benefits, but ethical and practical challenges make such studies difficult. Many people prefer to move forward with surgery when conservative options have failed. Continued research into patient selection, techniques and long-term outcomes is essential to improve care for this complex condition.
A proposed pathway for diagnosis and treatment has been recently proposed:1
Evaluation and management of suspected MALS
Information on current clinical trials is posted on the Internet at https://clinicaltrials.gov/. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
References
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The Genetic and Rare Diseases Information Center (GARD) has information and resources for patients, caregivers, and families that may be helpful before and after diagnosis of this condition. GARD is a program of the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health (NIH).
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