Feasibility, Safety, and efficacy of endovascular treatment for M1 hilltop Aneurysms: A retrospective study

Objective: This retrospective study aimed to evaluate the feasibility, safety, and efficacy of endovascular treatment (EVT) for M1 hilltop aneurysms, a specific M1 segment subtype located at the highest point of the middle cerebral artery (MCA). Methods: The study included 54 patients with M1 hilltop aneurysms who underwent EVT between December 2017 and [end date]. Treatment decisions were based on angiographic findings and patient characteristics. Clinical and radiological data were reviewed, and outcomes were assessed using the Raymond-Roy classification (RRC) and modified Rankin Scale (mRS). Follow-up radiological examinations were conducted at specific intervals. Results: EVT was successful in all 54 cases. Immediate postprocedural angiograms showed favorable occlusion (RRC I or II) in 59.3% and aneurysm remnants (RRC III) in 40.7%. Procedure-related complications occurred in 7.4% of patients, including thromboembolism and ICA dissection, with no permanent neurological impairment. During a mean 18.2-month follow-up, no neurological deterioration or aneurysmal rupture occurred. Most patients showed stable/improved occlusion on follow-up imaging, with a 14% recurrence rate. Retreatment was required in 2% of cases. Conclusions: EVT appears feasible, safe, and effective for treating M1 hilltop aneurysms. It resulted in favorable occlusion and low recurrence/retreatment rates. Neck diameter and stent usage influenced immediate outcomes and recurrence. Larger studies with longer follow-ups are needed to validate these findings further.