What is Median Arcuate Ligament Syndrome (MALS)?

Median Arcuate Ligament Syndrome (MALS)

Median Arcuate Ligament Syndrome (MALS) is a rare condition characterized by external compression of the celiac artery by the median arcuate ligament, causing postprandial abdominal pain, nausea, weight loss, and food aversion due to a combination of vascular compression and neurogenic factors involving the celiac plexus. 1, 2

Definition and Anatomy

• The median arcuate ligament is a fibrous band connecting the right and left hemidiaphragms that is present in everyone
• Celiac axis narrowing due to this ligament occurs in approximately 20% of the general population 1, 2
• Most cases of compression are asymptomatic due to collateral circulation from the superior mesenteric artery

Pathophysiology

MALS has a multifactorial etiology with two primary mechanisms:

1. Vascular mechanism: External compression of the celiac artery limiting blood flow to the bowel, resulting in ischemic symptoms 1
2. Neurogenic mechanism: Irritation of the celiac ganglion causing neuropathic pain 1, 3

Clinical Presentation

Typical symptoms include:

• Postprandial epigastric pain (most common)
• Nausea and vomiting
• Weight loss (often significant, up to 20 pounds)
• Food aversion (sitophobia)
• Abdominal pain exacerbated by exercise 3, 4

Diagnostic Approach

MALS is a diagnosis of exclusion. The American College of Radiology recommends:

1. CT angiography (CTA): First-line imaging to identify celiac stenosis, showing characteristic "J-shaped" narrowing of the proximal celiac artery 1, 2

2. Mesenteric angiography: Performed in lateral projection during both inspiration and expiration to document dynamic worsening of stenosis during expiration 1, 2

3. Duplex ultrasonography: To evaluate the influence of respiration on the stenotic degree of the celiac trunk 4

Management Options

Non-operative Management

• Supportive treatment with analgesics
• Dietary modifications
• Counseling
• Only about 33% of patients report improvement with non-operative management compared to 93% with operative management 1

Surgical Management

• Surgical release of the median arcuate ligament: First-line treatment, providing symptomatic relief in 84.6% of patients 1, 2
• Surgical approach options include:
  • Open decompression
  • Laparoscopic decompression
  • Robot-assisted laparoscopic decompression 5

Vascular Reconstruction

• Indicated when residual stenosis >30% persists after ligament release 2
• Options include:
  • Endovascular stenting (after surgical release)
  • Aorto-celiac bypass
  • Patch angioplasty
  • Resection with end-to-end anastomosis 4

Treatment Outcomes and Predictors of Success

Predictors of successful surgical outcome include:

• Postprandial pain pattern (81% cure rate)
• Age between 40-60 years (77% cure rate)
• Weight loss of 20 pounds or more (67% cure rate) 1

Combined approach of surgical release with vascular reconstruction when needed provides:

• Complete symptom resolution in 75% of patients
• Freedom from reintervention in 64% at 6 months 1, 2

Important Considerations

• Endovascular stenting alone without surgical release is not recommended due to persistent external compression 1, 2
• Patients with mesenteric collateralization on angiography may be less likely to benefit from surgical release 1
• Long-term follow-up with duplex ultrasound is necessary to monitor for persistent stenosis or aneurysmal degeneration 3

Controversies

Whether to reconstruct the celiac artery after median arcuate ligament release remains debatable:

• One study showed persistent resolution of symptoms in 76% of patients with revascularization versus 53% with decompression alone 1
• Another study found no significant difference in symptom relief between decompression alone versus decompression with reconstruction 1, 2

MALS remains a challenging diagnosis that requires exclusion of other causes of abdominal pain before consideration of surgical intervention.