Life-Threatening Pancreaticoduodenal Artery Aneurysm with Median Arcuate Ligament Syndrome

Abstract

A 60-year-old female presented with acute onset epigastric abdominal pain and transient hypotension. Her pain progressively worsened over a 12-hour period and resolved within 24 hours. Abdominal CT showed a mesenteric hematoma of unknown source. Interventional Radiology proceeded with mesenteric arteriography, demonstrating celiac axis stenosis and embolized a superior pancreaticoduodenal artery (PDA) pseudoaneurysm. The findings were consistent with post-stenotic dilatation and subsequent aneurysmal formation due to Median Arcuate Ligament Syndrome. The patient remained stable and was discharged home. The median arcuate ligament is a fibrous arch that straddles the aorta, connecting the diaphragmatic crura on each side of the aortic hiatus. The ligament typically lies superior to the origin of the celiac trunk; however, in 10-24% of the population, the ligament inserts lower, crossing the proximal portion of the celiac trunk, causing symptomatic compression in about 1%. Median Arcuate Ligament Syndrome is characterized by stenosis of the celiac artery secondary to impingement by the median arcuate ligament. It is a rare diagnosis of exclusion, classically presenting with postprandial abdominal pain, abdominal bruit, and weight loss. Stenosis of the celiac trunk causes decreased perfusion of the foregut. With increased retrograde blood flow, blood pressures, and wall tension, the smaller distal arteries' blood vessel wall can become damaged and even lead to aneurysm formation. Splanchnic artery aneurysms are relatively rare conditions with aneurysm rupture of greatest concern due to a mortality rate of 30% with PDA rupture.Figure 1The diagnosis of both MALS and PDA aneurysms can be made by angiography or incidentally on CT/MRI. Dynamic MRA can observe the celiac axis throughout the respiratory cycle, demonstrating the pathognomonic augmentation of stenosis of the artery during the expiratory phase to clinch the diagnosis of MALS and further rule out other causes of stenosis like atherosclerosis. Treatment for MALS with PDA aneurysm involves: Celiac axis/distal vessel revascularization and Median Arcuate Ligament release, which is paramount for prevention of recurrence. In conclusion, Median Arcuate Ligament Syndrome (MALS) is a rare cause of postprandial abdominal pain and is a diagnosis of exclusion. A potential life-threatening complication of MALS involves aneurysm formation, which if not identified can lead to rupture and sudden death without intervention.