Coil Embolization of Unruptured Cerebral Aneurysms Using Stents in Small Arteries Less Than 2 mm in Diameter

BACKGROUND: Data regarding the safety and effectiveness of stent placement in small vessels (<2 mm in diameter) for treating wide-necked cerebral aneurysms are limited. OBJECTIVE: To report our experience regarding coil embolization of unruptured cerebral aneurysms using stents (specifically the Neuroform Atlas) in small arteries <2 mm in diameter. METHODS: Patients with unruptured cerebral aneurysms treated with stent-assisted coil embolization between March 2017 and March 2021 in our hospital were included. RESULTS: Of the 137 cerebral aneurysms included in this study, 49 required stent placement and 48 were treated using the Neuroform Atlas in the small vessels measuring <2 mm in diameter (small vessel group [SVG]). In the SVG, 43 aneurysms (87.8%) demonstrated complete occlusion. Regarding complications, 2 (4.1%) patients had in-stent thrombosis during procedures and 5 (10.2%) experienced symptomatic thromboembolic complications, but only 2 (4.1%) had worsening of the modified Rankin scale ≥1 at 90 days after embolization. Patients with middle cerebral artery aneurysms had a higher risk of thrombotic events (5/18 patients, 27.8%), such as symptomatic thromboembolic complications or intraprocedural in-stent thrombus than those with other aneurysms (1/31 patients, 3.2%), in the SVG ( P = .0167). CONCLUSION: Stent-assisted coil embolization for unruptured cerebral aneurysms using stents, especially the Neuroform Atlas, in small arteries <2 mm in diameter is effective and feasible, but careful perioperative attention should be given to thrombotic events during the embolization of middle cerebral artery aneurysms.