To investigate the safety and efficacy of treatment with standalone flow diverter (FD) placement for unruptured large basilar trunk aneurysms (LBTAs).

Patients with unruptured LBTAs (maximum diameter ≥ 10 mm) who underwent standalone FD placement in the First Hospital of Harbin Medical University from January 2015 to August 2023 were retrospectively included. The occurrence of postoperative complications and follow-up imaging results were evaluated. The modified Rankin Scale (mRS) score was used to assess the clinical outcomes of patients; the O'Kelly-Marotta (OKM) grading was used to evaluate the aneurysm occlusion status during imaging follow-up.

A total of 14 patients (14 aneurysms) with unruptured LBTAs who received FD treatment were included, with a surgical success rate of 100%. The average maximum diameter of the aneurysms was 18.0±8.9 mm. All patients were treated with standalone FD placement without coil embolization. A total of 20 stents were used to treat 14 aneurysms, among which 3 stents were overlappingly placed in 2 patients and 2 stents were overlappingly placed in another 2 patients. Postoperatively, neurological complications occurred in 5 patients (35.7%), of which 4 (28.6%) first appeared during the perioperative period and 1 (7.1%) first appeared during the follow-up period. A total of 3 patients died, with a mortality rate of 21.4%. The first appearance of complications in all 5 patients with complications was ischemic complications, and 2 (14.3%) patients had combined hemorrhagic complications. The average last clinical follow-up time for all patients was 25.5±12.3 months. The rates of favorable outcome (mRS score > 2) at discharge and the last follow-up were 85.7% (12/14) and 71.4% (10/14), respectively. Imaging follow-up was obtained in 9 patients, with a median follow-up time of 6 (6, 8) months, and among them, 5 patients (55.5%) had complete aneurysm occlusion (OKM grade D) during follow-up.

The treatment of unruptured LBTAs with standalone FD placement has a high surgical success rate and acceptable safety and efficacy. However, clinicians should still be vigilant against the occurrence of fatal or disabling ischemic complications after surgery.