Embolization of very small (≤3 mm) unruptured intracranial aneurysms: A large single-center experience on treatment of unruptured versus ruptured cases

Abstract

In selected cases, embolization can be indicated for very small unruptured intracranial aneurysms. Previous studies reported high intraprocedural rupture rates. Recent improvements of endovascular devices and availability of small, soft platinum coils may lead to improved safety and efficacy profiles. Retrospective review of embolizations for unruptured and ruptured intracranial aneurysms with maximal diameter ≤3 mm between January 1, 2009, and January 15, 2018. Infectious aneurysms were excluded. Patient files were used to extract aneurysm characteristics, complications, and immediate and long-term results. We identified 99 embolizations for 97 patients with 100 aneurysms, of which 70 aneurysms were unruptured. Initial success rate was 92.9%. We observed 1 asymptomatic intraprocedural perforation of an unruptured aneurysm, accounting for 1.4% of unruptured cases (1% of all embolizations). Neurological morbidity was 2.8% for unruptured aneurysms and 3.3% for ruptured aneurysms (P= 0.89). There was no procedural mortality. Follow-up was available for 85 (93.4%) patients. After 28.2 months (2-77), there was no aneurysmal bleeding; 2 (2.2%) aneurysms needed retreatment. Long-term results (30.5 months [3-77]) were available for all unruptured aneurysms. Among 64 successfully embolized unruptured aneurysms, 5 (7.8%) had residual neck filling and 1 (1.5%) needed retreatment. There were no significant differences in patient characteristics or complications between ruptured and unruptured aneurysms. In the context of technical evolution of endovascular devices, we observed a procedural perforation rate lower than previously reported, low morbidity and no mortality. Further prospective studies are warranted to update our knowledge about safety of embolization for very small intracranial aneurysms.