Safety and efficacy of flow diversion for blood blister aneurysms: A comprehensive systematic review and meta-analysis

Blood blister aneurysms (BBAs) are surgically challenging with a high risk of bleeding and recurrence. Endovascular techniques, particularly flow diverters (FDs), offer a less invasive alternative to open surgery and conventional endovascular techniques by endovascular reconstruction and reducing aneurysm sac manipulation. This review aims to evaluate the safety and efficacy of FDs in treating BBAs, considering factors affecting outcomes. A systematic review of PubMed, Scopus, and Embase was performed aiming at studies reporting outcomes of FDs for BBAs. All reported radiologic, clinical, and complication outcomes were meta-analytically pooled. A total of 39 studies including 511 patients with BBAs treated with FDs were identified. The average patient age was 50.55 years, with 65.99% female, and 83.12% of aneurysms located in the internal carotid artery. Most aneurysms had ruptured before treatment, with an average maximum diameter of 2.94 mm. The mean time from symptom onset to FD treatment was 5.44 days, with Pipeline Embolization Devices used most frequently. The overall complete aneurysm occlusion rate was 87.56%, and 84.05% of patients had a good neurological outcome (mRS ≤ 2). In the subgroup analysis of large multicentric studies, the complete occlusion and good neurological outcome rates were 87.14% and 81.95%, respectively. Complications included intra-operative rupture (1.60%), hemorrhagic (5.62%), thromboembolic (6.89%), and neurologic (6.30%) complications, with a mortality rate of 6.55%. Older age and higher subarachnoid hemorrhage grades were associated with worse outcomes following flow diversion. This review demonstrates that FDs are safe and effective for treating ruptured BBAs, achieving promising rates of complete aneurysm occlusion and favorable neurological outcomes. However, complications such as intra-operative rupture and thromboembolic events still persist.