Indirect Revascularization for Pediatric Moyamoya Angiopathy: Insights from a Brazilian Cohort

<b>Background/Objectives</b>: Moyamoya angiopathy is a progressive occlusive cerebrovascular disorder and a relevant cause of pediatric stroke. While most published data originate from Asian and North American populations, reports from South America remain scarce. This study aimed to characterize the clinical, angiographic, and functional outcomes of pediatric patients with Moyamoya disease (MMD) or Moyamoya syndrome (MMS) who underwent indirect revascularization in a Brazilian cohort, and to contextualize these findings within the international literature. <b>Methods</b>: We retrospectively reviewed all patients under 18 years of age who underwent indirect bypass (EDAS/EDAMS) for MMD or MMS at a tertiary pediatric center in Curitiba, Brazil, between 2009 and 2023. Demographic, clinical, and angiographic data were analyzed, including postoperative Matsushima grading, and functional outcomes assessed by the modified Rankin Scale (mRS) and Glasgow Outcome Scale (GOS). All eligible patients received perioperative aspirin (3-5 mg/kg/day). <b>Results:</b> Fourteen patients (64% female; mean age 9.9 years) were included: 43% with MMD and 57% with MMS. Hemiparesis (86%), seizures (57%), and cognitive impairment (57%) were the most common symptoms. Most were classified as Suzuki stages II-III. All underwent indirect revascularization; 79% received bilateral procedures. Angiographic follow-up (14 hemispheres) showed good collateral formation (Matsushima grade A: 43%; B: 57%). Complications occurred in three patients (21%), and two (14%)-both MMD-developed new postoperative ischemic strokes despite receiving aspirin therapy. At 3.5 years of mean follow-up, the mean mRS was 1.9 ± 0.8 and the GOS was 4.0 ± 0.3. <b>Conclusions:</b> Indirect revascularization in this Brazilian pediatric cohort was feasible and safe, yielding outcomes comparable to international series. Collateral development correlated with functional improvement. These exploratory findings emphasize the importance of early diagnosis, standardized perioperative care, and long-term follow-up, and highlight the need for multicenter collaboration in Latin America.