Gradual Occlusion of an Anterior Choroidal Artery Aneurysm Using Overlapping Flow Diversion and Short-term Anticoagulation: A Case Report

Anterior choroidal artery aneurysms, in which the anterior choroidal artery arises from the aneurysmal sac, pose significant therapeutic challenges, as treatment risks include branch occlusion and devastating ischemic complications, including hemiplegia and hemianopia. We report a patient in their 70s with an incidentally diagnosed 12.2 mm unruptured right anterior choroidal artery aneurysm, in which three-dimensional angiography demonstrated that the anterior choroidal artery originated from the center of the aneurysm dome. During conservative observation, the aneurysm enlarged to 14.1 mm, necessitating intervention. We employed overlapping flow diverters (2 Pipeline Shield devices) with minimal loose coiling to facilitate controlled thrombosis. To prevent rapid aneurysm thrombosis and subsequent anterior choroidal artery occlusion, we administered modified triple antithrombotic therapy comprising dual antiplatelet agents (prasugrel 3.75 mg and aspirin 100 mg) and reduced-dose rivaroxaban (10 mg daily) for 30 days postoperatively. At 12-month follow-up, angiography demonstrated near-complete aneurysm occlusion (O'Kelly-Marotta grade C3) and a significant reduction in aneurysm size. Critically, during gradual aneurysmal shrinkage, the orifice of the anterior choroidal artery progressively migrated toward the aneurysm neck, allowing branch preservation while the sac underwent organized thrombosis. No perioperative or delayed ischemic complications occurred, and magnetic resonance imaging confirmed the absence of new infarction. This controlled thrombosis strategy combining mechanical flow diversion with time-limited pharmacological modulation successfully achieved aneurysm occlusion while preserving the sac-originating branch through gradual vascular remodeling. This approach addresses the fundamental therapeutic dilemma posed by anterior choroidal artery aneurysms with incorporated branches. It may represent a paradigm shift from acute treatment to controlled, gradual occlusion strategies for similarly challenging lesions.