The Effectiveness and Feasibility of Endovascular Coil Embolization for Very Small Cerebral Aneurysms: Mid- and Long-Term Follow-Up

Background: Endovascular embolization for very small cerebral aneurysms (VSCAs) is still controversial. We report our experience with endovascular coil embolization for these lesions and assess the feasibility and effectiveness. Methods: We conducted a review of our experience with endovascular treatment of a series of 19 patients with 20 VSCAs, located at the supraclinoid segment of the internal cranial artery (ICA) in seven, the cavernous ICA segment in three, the anterior communicating artery in five, vertebral artery-posterior inferior cerebellar artery in two, bifurcation of the middle cerebral artery in one, the pericallosal artery in one, and the P2 segment in one. The World Federation of Neurosurgical Societies classification before treatment was grade I in 14 patients and grade II in five patients. The strategy of endovascular treatment included coil occlusion, balloon-assisted coiling, and stent-assisted coiling. Occlusion rate was divided into (1) total/near total, occlusion rate 95-100%; (2) subtotal, occlusion rate 80-95%; and (3) partial, occlusion rate < 80%. Clinical outcome of patients with ruptured aneurysm was ascertained according to the Glasgow Outcomes Scale. Results: All patients were successfully treated with coil embolization; immediate angiography determined occlusion of the aneurysm, including total occlusion in five, subtotal occlusion in nine, and partial occlusion in six. During 1-2 years of follow-up, all aneurysms were confirmed as complete occlusion by control angiography. No recurrence or coil compaction occurred. No rehemorrhage or ischemic stroke occurred. Conclusion: Endovascular coil embolization for VSCAs is effective and feasible. Initial subtotal or partial aneurysm occlusion might progress to total occlusion.