Characteristics and Trends in Median Arcuate Ligament Syndrome (MALS) Associated Visceral Artery Aneurysms: A Systematic Descriptive Review of the Literature

Introduction: Median Arcuate Ligament Syndrome (MALS) is associated with true aneurysms, mainly of both the pancreaticoduodenal artery (PDA) and gastroduodenal artery (GDA). Although rare, their potential for rupture and adverse clinical outcomes warrants analysis. Prior studies suggest high rupture rates even for smaller aneurysms under 2 cm in this setting. We performed a systematic literature review, synthesising the evidence on visceral artery aneurysms related to MAL syndrome, with a focus on descriptive analyses of aneurysm size, presentation, rupture rates, and management. 

Methods: Literature search was performed using (Medline, EMBASE, Emcare and CINAHL). Inclusion criteria included true aneurysms secondary to MALS with or without rupture. The cases with pseudoaneurysms, concomitant pathologies eg, pancreatitis, conservatively managed aneurysms and articles with non-granular pooled data were excluded. Cases were assessed according to demographics, clinical presentation, aneurysm diameter, aneurysm rupture and management technique. 

Results: 39 articles describing 72 patients were identified. Aneurysm diameter in symptomatic patients was not significantly different from asymptomatic patients {21.0 and 22.3 mm respectively, P =.84}. Ruptured aneurysms were overall smaller than non-ruptured at presentation {12.3 mm v 30.8 mm respectively, P =.02}. Patients presented with abdominal pain (75.6%), nausea/vomiting (15.6%), hypotension (33.9%), shock (20.0%) and haemodynamic collapse (8.9%). 56.9% of all cases were managed with an endovascular approach, 19.4% were managed with an open surgical approach, and 23.6% were managed hybrid. 

Conclusion: This review suggests visceral artery aneurysms associated with median arcuate ligament rupture at variable sizes. Despite inability to clearly correlate size and rupture risk, our data supports prompt intervention irrespective of size, given the adverse outcomes. Further research is critically needed to clarify size thresholds or other predictors to guide management.