Pediatric Hemorrhagic Moyamoya Disease

BACKGROUND AND OBJECTIVES: Pediatric hemorrhagic moyamoya disease (MMD) is a critical subtype associated with high morbidity; however, hemorrhage-specific prognostic factors remain poorly defined. The aim of this study was to define the clinical course, identify factors associated with hemorrhagic presentation and recurrence, and evaluate long-term outcomes in a large pediatric cohort. METHODS: This retrospective cohort study included children diagnosed with MMD between 2003 and 2023. Hemorrhagic MMD was defined as acute intracranial hemorrhage on CT/MRI within 72 hours of symptom onset, excluding traumatic or aneurysmal causes. Standardized data collection encompassed Suzuki staging, posterior communicating artery (PcomA) and anterior choroidal artery (AChA) dilatation, modified Rankin Scale (mRS) scores at admission and follow-up, and recurrence events. Multivariable logistic regression and Cox proportional hazards models were used to identify factors associated with hemorrhagic MMD and stroke recurrence. RESULTS: < 0.0001). DISCUSSION: Hemorrhagic MMD is an aggressive subtype characterized by posterior collateral vulnerability, female predominance, and older age. Admission mRS score ≥2 and AChA dilatation are key factors strongly associated with adverse outcomes. Conventional angiographic classification does not demonstrate a significant association with hemorrhage outcome; assessment of the posterior circulation is critical for stratifying patient outcomes and guiding early intervention.