Comparative analysis of characteristics, management and clinical outcome of blood blister-like aneurysms treated with flow diverter devices: a systematic review and meta-analysis of 30 studies.

Background and aim: Because of relatively little data for blood blister-like aneurysms (BBAs) treated with flow diverter (FD) devices, existing studies failed to provide comprehensive analysis for the characteristics, management, clinical outcome of the disease. Therefore, we collected and analyzed current evidence aiming to provide quantitatively pooled results for the management, complication, clinical and angiographic outcomes as well as the risk factors of prognosis of BBAs treated with FD devices.

Methods: A systematic search of PubMed, SCOPUS, Cochrane Library and Web of Science up to May 1, 2024 was conducted for relevant studies. The primary outcomes were to expound the management, characteristics and clinical outcomes of BBAs treated with FD devices. The secondary outcomes were to determine the difference of characteristics and outcomes, as well as risk factors of BBAs treated with FD devices. Two reviewers assessed trial quality and extracted the data independently. All statistical analyses were performed using the standard statistical procedures provided in Review Manager 5.2 and Stata 12.0.

Results: A total of 30 reports with 311 of 783 BBA patients were identified. The pooled results indicated that 76.3% BBAs located in internal carotid artery (ICA) and 85% and 84% patients experienced complete occlusion and modified Rankin scale (mRS) score 0-2 respectively at follow-up time. Female BBAs patients (69.9%) were more prevalent and 88.5% patients experienced a favorable outcome at discharge. The overall and periprocedural complications account for 16.8% and 9.1% respectively. The pooled results showed that the incidence of complete occlusion was 50% (95% CI: 31%－69%), 80% (95% CI: 67%－92%) and 84% (95% CI: 77%－91%) at immediate, short and longterm angiographic results respectively. In addition, the favorable, moderate and poor clinical outcomes evaluated with mRS were 89% (95% CI: 85%－94%), 13% (95% CI: 5%－21%), and 8% (95% CI: 3%－13%) respectively. We found that compared to moderate or poor outcomes, patients with good outcomes experienced significantly lower preoperative scores (MD -1.24; 95% CI -1.94－-0.53), more complete occlusion (OR 5.17; 95% CI 1.26－21.15) and less complications (OR 0.20; 95% CI 0.08－0.47) respectively. It was observed that patients experienced a complication had higher onset Hunt-Hess scale (MD 0.49; 95% CI 0.03－0.96) and Fisher's score (MD 1.43; 95% CI 0.72－2.13) respectively. Patients with good outcomes experienced younger age (MD -5.76 years; 95% CI -11.31－-0.21) and lower onset Hunt-Hess scale (MD -0.96; 95% CI -1.45－-0.47) respectively.

Conclusions: BBA was middle-aged female predominant and common in ICA. The majority of patients generally experienced favorable outcome with low incidence of periprocedural complications. In addition, good outcomes benefited from lower preoperative scores, more complete occlusion, less complications and younger age. Higher onset Hunt-Hess scale and Fisher's score may increase the risk of complications. Future studies with enough sample size and long follow-up are required to clear the management, long-term outcome and risk factors of BBAs.