Coil embolization for ruptured and unruptured very small intracranial aneurysms: A retrospective review of a 10-year single-center experience

Because of the risk of intraoperative rupture and technical difficulties, coil embolization of very small aneurysms (VSIAs) with a diameter of ≤3 mm is challenging. Herein, we reviewed our treatment strategies and outcomes in performing coil embolization for VSIAs compared to those for larger sized intracranial aneurysms (IAs) with 4 to 4.5 mm. We retrospectively reviewed the data on ruptured and unruptured VSIAs and larger-sized IAs treated with coiling from January 2012 to June 2021. Saccular IAs treated with coil embolization and followed up for at least 6 months with imaging studies were included in the study. Fifty-eight VSIAs (27 subarachnoid hemorrhages [SAH group] and 31 unruptured hemorrhages [URA group]) were identified. The wide-necked VSIAs were significantly more common in the URA group (90.3% vs 63.0%, P = .013). Procedural complications occurred in 8 cases (13.8%)intra-procedural rupture (n = 3), coil prolapse (n = 3), and thromboembolic events (n = 2). Complications were more frequent in the SAH group (P = .020). SAH was an independent risk factor for procedural complications (odds ratio, 11.293 [95% confidence interval1.173–108.684], P = .036), and the outcomes were affected by SAH presentation (P = .007) and poor clinical status of SAH (P = .001). When compared with larger IAs (n = 57), there were no significant differences in treatment outcomes, procedural complications, and clinical outcomes. VSIAs ≤ 3 mm in diameter were successfully treated with coil embolization, with reasonable procedure-related complications and treatment outcomes. The safety and efficacy of coil embolization for VSIAs were comparable to those of 4 to 4.5 mm sized IAs in this single-center cohort.