Surgical treatment of intracranial blister aneurysms: A systematic review

•Blister aneurysms (BAs) are relatively rare vascular malformations-.•BAs treatment is challenging using either surgical or endovascular approaches.•Surgery is frequently associated with controversial results.•This study aims to investigate clinical-radiological outcomes and complications of surgery for BAs. Intracranial blister aneurysms (BAs) are challenging vascular lesions related to high morbidity and mortality rates. Different surgical and endovascular techniques have been proposed to treat BAs; however, there is no consensus on a preferred treatment. To systematically review the pertinent literature on clinical and radiological outcomes of different surgical treatments for BAs management, to meta-analyze their clinical and radiological outcomes, and compare these results with those from recent meta-analyses on endovascular treatments for BAs. The present study was consistently conducted according to the PRISMA guidelines. Five different online medical databases (PubMed, Medline, EMBASE, Scopus, and Web-of-Science) were screened from 2010 through 2020. Papers reporting clinical and radiological outcomes of different surgical treatments for BAs were considered. Event rates were pooled across studies using random-effects meta-analysis. A total of 35 studies reporting on 514 patients (534 aneurysms) were included. Aneurysm clipping in 223 patients (45.4%; 95% CI 21.9−53.8), bypass and trapping in 87 (17.7%; 95% CI 1.89−21.6), clipping and wrapping in 82 (16.7%; 95% CI 3.71−19.0), and wrapping in 33 (6.7%; 95% CI 0.0−4.87) were the mostly common performed treatments. Complete occlusion rate was reported in 90.7% of patients. The complication rate was as high as 61.1%, the mortality rate was 7.4%, and the mean mRS at follow-up was 2.5. Our meta-analysis suggests that surgical treatments for BAs are related to higher occlusion, complications and mortality rate than endovascular strategies. However, there is a high-heterogeneity among the included studies and data are poorly reported; so comparing the two type of treatments is unreliable in order to establish which one is better.