Endovascular embolization of very small cerebral aneurysms

Background : Very small cerebral aneurysms are considered to be one of the challenges for endovascular treatment, with difficulty for catheterization and high risk for intraoperative rupture. We report the treatment of very small (< 3-mm) cerebral aneurysms by coil embolization.
Materials and Methods : We performed a retrospective analysis of 11 consecutive patients with very small aneurysms treated by coil embolization in our institute between February 2007 and February 2009.
Results : Three-dimensional rotational angiography (3DRA) was most accurate in the detection of these aneurysms; 3DRA revealed the aneurysms in two patients in whom conventional angiography failed to demonstrate the aneurysms. The Hunt-Hess (HH) grade was grade 0 (unruptured aneurysm) in one patient and grade I in ten patients. Coil embolization was successfully performed in 11 patients. Complete (n = 8) or near complete (n = 3) immediate occlusion was obtained. One or three soft coils were used in all the patients with the shortest available length. Balloon assistance was used in one patient and stent assistance was used in seven patients. Although coil migration into the MCA was seen in one patient and intraoperative aneurismal rupture occurred in one patient, no untoward clinical complication was seen. Follow-up DSA in 11 patients demonstrated persistent occlusion (n = 9) or progressive thrombosis (n = 2) of the aneurysms. All the patients with available follow-up had a modified Rankin Score (mRS) of 0.
Conclusion : HH grade 0 and I very small cerebral aneurysms can be treated by endovascular coil embolization. Use of short, soft coils and balloon/stent assistance is useful.