Blister aneurysms

Abstract

Blister aneurysms comprise about 1 % of ruptured intracranial aneurysms. They are associated with higher rates of rebleeding and, as a result, with greater mortality and morbidity than typical aneurysms. Because of rarity, the etiology and pathology are poorly understood. Diagnosis relies on a stereotypical appearance and location at non-branch points on the internal carotid artery at angiography, together with inspection at surgery. They are increasingly seen involving other intracranial arteries and generally considered to be caused by atherosclerotic mural disease. Surgical clipping is difficult because of their small size, sessile shape, and thin sac walls. It is frequently complicated by operative rupture, and alternative wrapping and trapping are often required. For these reasons, endovascular treatments are increasingly used as an alternative. The recent introduction of high mesh density stents, designed to redirect blood flow away from aneurysms and reinforce the parent artery, has stimulated the development of new procedures to manage these lesions. Initial experiences with flow-diverting stents have shown a substantial improvement in outcomes, and stent procedures are rapidly being accepted as the intervention of choice.