Efficacy and safety of endovascular coil embolization for unruptured middle cerebral artery aneurysms: middle-term clinical and imaging outcomes with 3 years mean follow-up periods, a 16-year experience.

The anatomical characteristics of middle cerebral artery aneurysms make endovascular treatment difficult. This study evaluated the efficacy and safety of endovascular treatment of unruptured middle cerebral artery aneurysm in preventing rupture. A retrospective review of patients who underwent coil embolization for unruptured middle cerebral artery aneurysm between 2006 and 2022 at Nagoya University Hospital with at least 12 months followed up was conducted. Imaging and clinical outcomes were described using the Raymond classification and the modified Rankin Scale, respectively. Good imaging outcome was defined as complete occlusion or neck remnant and clinical outcome as modified Rankin Scale score of 0-2. Patients were divided into initial and recurrent group based on the number of treatments, pre- and post-stent groups based on when stents became available in Japan. A total of 77 patients (80 with aneurysms) were included in the final analysis. Their average age was 60.3 years, and their average follow-up period was 38 months. Favorable clinical outcomes were achieved for 96.2% among 66 (97.0%) initial and 11 (91.7%) recurrent aneurysms. Furthermore, good imaging outcomes were obtained in 90.0 %, and 5% had permanent symptomatic ischemic complications. The pre-stent group had a significantly higher proportion of patients with narrow-neck aneurysms than the post-stent group. There were no significant differences in terms of imaging and clinical outcomes or complication rates. The present study demonstrated that endovascular treatment of unruptured middle cerebral artery aneurysm was safe and effective in preventing rupture. The wide-neck aneurysm was also well embolized by using adjunctive technique.