Endovascular Management of Moyamoya Type II Endoleak Utilizing a CO₂-Assisted Protection Strategy: A Case Report

Area of Science:

• Vascular Surgery
• Interventional Radiology
• Endovascular Repair

Background:

• Moyamoya type II endoleaks (T2EL) are a challenging complication following endovascular aneurysm repair (EVAR).
• These endoleaks often involve complex collateral networks, complicating standard embolization techniques and increasing the risk of persistent aneurysm sac enlargement.
• Refractory T2ELs pose a significant risk for EVAR failure.

Purpose of the Study:

• To describe a novel technique for treating a refractory Moyamoya type II endoleak.
• To demonstrate the efficacy of n-butyl cyanoacrylate (NBCA) embolization assisted by intra-arterial carbon dioxide (CO2) flow modulation.
• To report successful management of post-EVAR aneurysm sac enlargement due to T2EL.

Main Methods:

• A case report of an 84-year-old woman with refractory Moyamoya T2EL 5 years post-EVAR.
• Angiography revealed retrograde perfusion via inferior mesenteric artery and complex vasa vasorum collaterals.
• Intra-arterial CO2 injection was used to transiently suppress antegrade flow, creating a controlled "to-and-fro" pattern for NBCA delivery.

Main Results:

• Complete occlusion of the Moyamoya type II endoleak was achieved using NBCA under CO2 flow modulation.
• No reflux or non-target embolization occurred during the procedure.
• One-year follow-up CT confirmed stable aneurysm sac size with no re-dilation.

Conclusions:

• CO2-assisted NBCA embolization is a feasible strategy for treating complex, refractory Moyamoya type II endoleaks.
• This technique effectively displaces competing flow, allowing safe and selective embolization.
• Successful management of T2EL can prevent EVAR sac enlargement and improve patient outcomes.