Use of a flow diverter in a small-caliber end artery anterior choroidal dissecting pseudoaneurysm: illustrative case

BACKGROUND: Anterior choroidal artery (AChA) fusiform aneurysms are exceedingly rare and associated with high rebleeding and mortality rates. Their difficult anatomy comes with a broad range of treatment options, including bypass, stent-assisted coiling, and flow diversion. Currently, flow diverters are approved for large-caliber internal carotid artery segment aneurysms. However, many institutions have expanded their use to distal small-caliber vessels, which raises questions regarding device sizing and long-term patency. The authors present a dissecting distal AChA fusiform pseudoaneurysm treated successfully with flow diversion. OBSERVATIONS: A 40-year-old woman with monoclonal gammopathy of unknown significance, lichen sclerosis, and an unspecified connective tissue disease presented with diffuse subarachnoid hemorrhage. She had a dissecting, 5 × 3–mm, left AChA pseudoaneurysm 4 mm distal to the origin of the vessel. A 2.5-mm flow redirection endoluminal device was deployed. There were no procedural complications. A 6-month cerebral angiogram showed device patency and no pseudoaneurysm remnant. These results were maintained at 1 year as seen on head magnetic resonance angiography. LESSONS: Flow diversion is a successful and safe therapeutic intervention for challenging intracranial aneurysms originating from small-caliber vessels supplying eloquent vascular territories.