Background Endovascular coiling of small, intracranial aneurysms remains controversial and difficult, despite advances in coil embolization technology. We sought to describe our experiences using coils designed for treating small aneurysms and the efficacy and outcomes we observed.

Methods We retrospectively reviewed data for 62 small aneurysms (<3.99 mm largest diameter) in 59 patients. Aneurysm occlusion rates, complications rates, and coil packing densities were compared between subgroups based upon coil type and rupture status.

Results Ruptured aneurysms predominated (67.7%). Average aneurysm dimensions were 2.99 ± 0.63 by 2.51 ± 0.61 with an average aspect ratio of 1.21 ± 0.34. Coil brands included Balt Optima (29%), Microvention Gel (24.2%), and Penumbra (19.4%). Average packing density was 34.3 ± 13.5. Occlusion rate was 100% in unruptured aneurysms although 84% were treated with adjuvant devices. For ruptured aneurysms, complete occlusion or stable neck remnant was achieved in 88.6% while recanalization was seen in 11.4%. No episodes of rebleeding occurred. Average packing density (35.6 vs 36.3, p = .919) and coil type (p = .056) did not statistically impact occlusion class. Aspect ratio was smaller in aneurysms with technical complications (p = .281) and aneurysm volume was significantly smaller in those with coil protrusion (p = .018). There was no difference in complication rates between ruptured and unruptured aneurysms (11 vs 3, p = .308) and coil types (p = .830).

Conclusions Despite advances in coil embolization devices, coiling of small intracranial aneurysms is still scrutinized with surgeons often citing higher interventional risks. High occlusion rates are achievable, especially in unruptured aneurysms, with coil type and packing density suggesting association with complete occlusion. Technical complication rates may be influenced by aneurysm geometry including aspect ratio and aneurysm volume. Advances in endovascular technologies have revolutionized the treatment of small aneurysms with this series clearly demonstrating excellent aneurysm occlusion especially in unruptured aneurysms.

Disclosures S. Begley: None. T. White: None. K. Shah: None. J. Turpin: None. D. Toscano: None. I. Teron: None. T. Link: None. A. Patsalides: None. H. Woo: None.