Clinical impact of collateral circulation in patients with median arcuate ligament syndrome

Abstract

Purpose: We aimed to analyze computed tomography (CT) findings and medical records of patients diagnosed with median arcuate ligament syndrome (MALS) and evaluate possible risk factors associated with vascular complications that develop in patients with MALS.

Methods: This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. A total of 37 consecutive patients were diagnosed with MALS using both axial and sagittal CT reconstruction imaging at a single institution over a 7-year period. Dynamic contrast-enhanced CT data, medical records, and angiography results were reviewed.

Results: Thirty-two (86.5%) patients were asymptomatic and incidentally diagnosed with MALS using CT. Seventeen (45.9%) patients exhibited significant arterial collateral circulations and nine (24.3%) were found to have splanchnic artery aneurysms, including one (2.7%) with acute bleeding secondary to aneurysm rupture. Peripancreatic vascular network including pancreaticoduodenal arcades and dorsal pancreatic artery was the most common site for development of both collateral circulations (16/22, 72.7%) and aneurysms (9/16, 56.3%). Splanchnic artery aneurysms were significantly more common in patients with collateral circulations (8/17, 47.1%) compared with those without collateral circulations (1/20, 5%) (P < 0.01). At least one peripancreatic vascular aneurysm was found in five of nine patients with splanchnic artery aneurysms (55.6%).

Conclusion: Splanchnic artery aneurysms are not uncommon in asymptomatic patients with collateral circulations caused by significant celiac trunk stenosis or obstruction due to median arcuate ligament. Therefore, careful imaging evaluation is necessary in patients with peripancreatic collateral circulations associated with MALS and regular follow-up is recommended for possibility of aneurysm development and rupture. Prophylactic endovascular treatment should be specifically performed in patients with pancreaticoduodenal arcade aneurysms to prevent life-threatening aneurysm rupture regardless of size.

Figure 1 a, b

Representative case of a 48-year-old man diagnosed with median arcuate ligament syndrome (MALS). Contrast-enhanced arterial phase axial CT image (a) shows abrupt slit-like luminal narrowing (arrow) in the proximal celiac trunk at the fibrous attachment site of the diaphragmatic crura. Sagittal reconstructed arterial phase CT image (b) reveals hooked appearance of the proximal celiac trunk (arrow) due to MAL (asterisk) indenting the superior border of the celiac trunk.

Figure 2 a, b

A 48-year-old woman incidentally diagnosed with MALS at screening CT. Sagittal reconstructed arterial phase CT image (a) shows complete obstruction of the celiac trunk due to thickened MAL (asterisk) and the U-shaped configuration of the expected celiac trunk (dotted line). Coronal maximum intensity projection CT image (b) reveals collateral circulations via gastroduodenal artery (white arrowhead), pancreaticoduodenal arcades (black arrowheads), and dorsal pancreatic artery with aneurysms (arrows).

Figure 3 a, b

A 40-year-old man presented with epigastric pain. Sagittal reconstructed arterial phase CT image (a) shows complete obstruction of the celiac trunk due to thickened MAL (asterisk) and the U-shaped configuration of the expected celiac trunk (dotted line), together with a large thrombosed aneurysm (arrowhead) and minimal narrowed superior mesenteric artery orifice. Superior mesenteric angiography (b) reveals collateral circulation and multiple aneurysms (arrowheads) in the pancreaticoduodenal arcades and retrograde contrast filling of the celiac trunk branch vessels with a synchronous splenic artery aneurysm (arrow).

Figure 4 a–c

A 52-year-old woman with sudden abdominal pain. Contrast-enhanced arterial phase axial CT image (a) shows an enhancing nodular structure suggesting aneurysm (arrow) in the peripancreatic area, and contrast extravasation indicating active bleeding (arrowheads) along the duodenum and mesentery with large amount of acute hematomas in the abdomen. Coronal maximum intensity projection image (b) reveals the ruptured aneurysm and contrast extravasation from the inferior pancreaticoduodenal arcade. Sagittal reconstructed arterial phase CT image (c) shows significant celiac trunk stenosis due to MAL (arrow) with large amount of mesenteric and retroperitoneal hematomas (asterisks).