Outcomes of stent-assisted coil embolization of intracranial aneurysms with a small parental vessel diameter

Background Stent-assisted coil embolization (SACE) is widely used for treating cerebral aneurysms, particularly bifurcation aneurysms. Although stents are typically indicated for parent vessels larger than 2 mm, their use in small-diameter vessels (<2 mm) hasn’t been extensively studied. This study evaluates the safety of SACE with small-diameter vessels. Methods This retrospective study analyzed 324 patients who underwent SACE between 2010 and 2023. Patients were divided into the small-diameter (SD) group (<2 mm, n = 100) and the normal diameter (ND) group (> 2 mm, n = 224). Perioperative ischemic complications and their risk factors were compared between the two groups. Results Intraoperative thrombi occurred in 6 patients (6.0%) in the SD group, with 4 (4.0%) asymptomatic and 2 (2.0%) transiently symptomatic. In the ND group, thrombi occurred in 7 patients (3.1%), with 5 (2.2%) asymptomatic and 1 (0.4%) experiencing worsened modified Rankin Scale (mRS). Symptomatic ischemic complications occurred in 5 patients (5.0%) in the SD group and 22 patients (9.8%) in the ND group, with 2 (2.0%) and 7 (3.1%) showing worsened mRS, respectively. A neck diameter > 5.5 mm was identified as a risk factor for perioperative ischemic complications. Conclusion SACE can be safely performed in patients with SD parent vessels without increasing ischemic complications. However, there was only a trend toward higher frequency of intraoperative thrombi in the SD group, highlighting the need for preventive measures and prompt intervention. Having a wide neck diameter > 5.5 mm was identified a risk factor for periprocedural ischemic complications in the SD group.