Median Arcuate Ligament Syndrome (MALS)
Diagnosis
MALS is a diagnosis of exclusion requiring both clinical symptoms AND imaging confirmation of celiac artery compression, but compression alone is present in 20% of asymptomatic individuals and does not warrant intervention. 1, 2
Clinical Presentation
- Classic triad: Postprandial epigastric pain (occurring 30-60 minutes after meals), unintentional weight loss (particularly ≥20 pounds), and food avoidance (sitophobia) 1, 2, 3
- Additional symptoms include nausea, vomiting that worsens after meals, and occasionally an epigastric bruit 1, 4
- Age 40-60 years is the typical demographic, though younger patients can be affected 1, 5
Imaging Workup
- CT angiography (CTA) is the initial imaging modality of choice, looking for proximal celiac artery narrowing in a characteristic "J-shaped" configuration 1, 3
- Mesenteric angiography with lateral projection during both inspiration and expiration demonstrates dynamic worsening of stenosis on expiration (pathognomonic finding) and identifies collateral circulation 1, 3
- Patients with angiographic collateralization are less likely to benefit from surgical release than those without collaterals 1
Critical Diagnostic Pitfall
Do not intervene based on imaging findings alone—celiac compression is a normal anatomic variant in 20% of the population. 1, 2 Extensive evaluation to exclude other gastrointestinal pathology (peptic ulcer disease, inflammatory bowel disease, malignancy, mesenteric vasculitis) is mandatory before attributing symptoms to MALS. 5, 4, 6
Treatment Algorithm
Initial Management: Supportive Measures
Begin with supportive treatment including analgesics and continued diagnostic evaluation for alternate causes of abdominal pain. 1, 2, 3 This approach is rated as appropriate (7/9) by the American College of Radiology for suspected MALS, acknowledging the controversial nature of this diagnosis. 2
- Nonoperative approaches include counseling, analgesia, and dietary modifications 1
- In one retrospective study, only 33% of conservatively managed patients reported symptom improvement compared to 93% with operative management 1
Surgical Intervention: First-Line Definitive Treatment
Surgical release of the median arcuate ligament is the first-line treatment for symptomatic MALS, achieving symptomatic relief in 84.6% of patients. 1, 2, 3, 7
Surgical Approach Options
- Laparoscopic MAL release is safe and effective with a 10.3% conversion rate to open surgery and no mortality 7
- Open surgical decompression through median supraumbilical laparotomy with complete exposure of the celiac artery and its branches 5
- Robotic-assisted release is also an option 6
Predictors of Successful Surgical Outcomes
The American College of Radiology identifies three key predictors: 1, 2, 3
- Postprandial pain pattern: 81% cure rate
- Age 40-60 years: 77% cure rate
- Weight loss ≥20 pounds: 67% cure rate
Conversely, patients with cardiovascular risk factors (atherosclerotic disease) have poorer outcomes, with 67% of nonresponders having these risk factors versus only 27.3% of responders. 7
Adjunctive Revascularization
Additional revascularization should be considered if residual celiac stenosis >30% persists after ligament release. 1, 3
- Options include endovascular stent placement or surgical bypass (primary reanastomosis or interposition grafting) 1
- A multidisciplinary approach with stenting or bypass as needed achieves 75% symptomatic relief and 64% freedom from reintervention at 6 months 1
- One study showed 76% persistent symptom resolution with revascularization plus decompression versus 53% with decompression alone 1
- However, another study found no significant difference in symptom relief (P=0.72) or reintervention rates (P=0.26) between groups at 5-year follow-up 1
The data on whether to routinely add revascularization remains equivocal, but it should be strongly considered for residual stenosis >30%. 1, 3
Role of Endovascular Therapy Alone
Endovascular stent placement without surgical ligament release is contraindicated and leads to poor outcomes due to persistent extrinsic compression, chronic vessel wall changes, and risk of stent fracture or migration. 1, 2, 3
- Stenting may only be performed after surgical release if residual stenosis persists 1, 3
- Isolated case reports of successful angioplasty with stenting exist but represent exceptions, not standard practice 8
Systemic Anticoagulation
Systemic anticoagulation has no role in MALS without evidence of thrombosis. 1, 2, 3 Limited data support its use, and it receives an appropriateness rating of only 5/9 for chronic mesenteric ischemia scenarios. 9
Pathophysiology Considerations
Emerging evidence suggests MALS is primarily a neurogenic disorder rather than a vascular disease. 7, 6
- Symptoms result from altered sensation and pain from somatic nerves in the splanchnic plexus, not purely from vascular compromise 5, 7
- Five patients with residual celiac stenosis or occlusion on postoperative duplex reported complete symptom resolution, supporting the neurogenic hypothesis 7
- This explains why symptom relief occurs even when postoperative imaging shows persistent stenosis 7
Follow-Up
Long-term follow-up with annual duplex ultrasound and clinical evaluation is mandatory to assess for persistent stenosis or aneurysmal degeneration requiring revascularization. 5 Patients should be monitored for symptom recurrence, which may indicate need for additional intervention.