Angiographic outcomes after indirect revascularization in pediatric Moyamoya disease: a systematic review and Meta-analysis.

Moyamoya disease is a rare progressive cerebral vasculopathy characterized by narrowing or occlusion of the internal carotid arteries, leading to the formation of fragile collateral vessels and a high risk of ischemic events, especially in pediatric patients. Although direct revascularization techniques are commonly used, they are technically challenging in children due to vascular fragility and anatomy. Indirect revascularization techniques favor the formation of new blood vessels through alternative flow routes. Their efficacy is usually assessed using the Matsushima scale, which measures the degree of revascularization achieved. This study aims to describe postoperative angiographic outcomes of indirect revascularization techniques in pediatric patients with Moyamoya disease. A systematic review and meta-analysis was performed following PRISMA guidelines, searching six databases (PubMed, Embase, Scopus, Web of Science, CENTRAL and Google Scholar) for observational studies that evaluated indirect revascularization techniques in pediatric patients with Moyamoya disease. Seventeen studies comprising 1360 hemispheres were included. Primary outcomes were the proportions of angiographic revascularization according to grades A, B, and C of the Matsushima scale. Secondary outcomes included postoperative clinical complications such as stroke, transient ischemic attacks (TIAs), seizures, bleeding, mortality, and functional status assessed using the modified Rankin scale (mRS ≤2). Meta-analyses were performed with random-effects models in R (version 4.2.3) and risk of bias was assessed with the MINORS tool. Meta-regression was applied to explore possible predictors of outcomes. The certainty of evidence was assessed with the GRADE approach. The combined proportions of hemispheres achieving Matsushima grades A, B and C were 47.1% (95% CI: 38.4-55.9; I