Flow-diversion treatment for unruptured nonsaccular intracranial aneurysms of the posterior and distal anterior circulation: A meta-analysis

BACKGROUND: Treatment management and outcomes of unruptured nonsaccular aneurysms are different compared with their saccular counterparts. PURPOSE: Our aim was to analyze the outcomes after flow diversion among nonsaccular unruptured lesions. DATA SOURCES: A systematic search of 3 data bases (2005–2019) was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. STUDY SELECTION: We included studies reporting flow diversion for nonsaccular unruptured aneurysms of the posterior and distal anterior circulations. Anterior circulation lesions were included if located distal to the petrocavernous and supraclinoid ICA (MCA, A1, anterior communicating artery, A2). Giant dolichoectatic holobasilar lesions were excluded because of their poor treatment outcomes. DATA ANALYSIS: Aneurysm occlusion and complication rates were calculated (random effects meta-analysis). DATA SYNTHESIS: We included 15 studies (213 aneurysms). The long-term adequate occlusion rate was 85.3% (137/168; 95% CI, 78.2%–92.4%; I2 4 42.3%). Treatment-related complications were 17.4% (41/213; 95% CI, 12.45%–22.4%; I2 4 0%). Overall, 15% (37/213; 95% CI, 10%–20%; I2 4 0%) were ischemic events. Procedure-related morbidity was 8% (20/213; 95% CI, 5%–12%; I2 4 0%). Fusiform or dissecting types had comparable adequate occlusion (116/146 4 83%; 95% CI, 74%–92%; I2 4 48% versus 33/36 4 89%; 95% CI, 80%–98%; I2 4 0%; P 4 .31) and complication rates (35/162 4 17%; 95% CI, 10%–25%; I2 4 24% versus 11/51 4 19%; 95% CI, 10%–31%; I2 4 0%; P 4 .72). Aneurysm size (.10 versus #10 mm) was independently associated with a higher rate of complications (OR 4 6.6; 95% CI, 1.3–15; P 4 .02). The rate of ischemic events after discontinuation of the antiplatelet therapy was 5% (5/93; 95% CI, 2%–9%; I2 4 0%). LIMITATIONS: Small and retrospective studies were available for this meta-analysis. CONCLUSIONS: Unruptured nonsaccular aneurysms located in the posterior and distal anterior circulations can be effectively treated with flow diversion. Nevertheless, treatment-related complications are not negligible, with about 15% ischemic events and 8% morbidity. Larger size (.10 mm) significantly increases the risk of procedure-related adverse events.