Supplementary Material for: Hemorrhage Risk in Pediatric Patients with Multiple Intracranial Arteriovenous Malformations

Background/Aims: This study aims to characterize the clinical features, treatment strategies, and annual hemorrhage incidence rate of pediatric patients with multiple arteriovenous malformations (MAVM). Methods: The PubMed and EMBASE databases and the arteriovenous malformations (AVM) database at the Johns Hopkins Hospital were searched for reports of pediatric patients (under 21 years of age) with MAVM. Data related to demographics, clinical features, management, and treatment outcomes were analyzed using descriptive statistics. Twenty-four pediatric patients met the inclusion criteria. Results: The annual hemorrhage incidence rate was 2.1%. The most common presenting features were neurological deficit (38%) and hemorrhage (21%). Treatment with embolization has become the most frequently used modality. In patients undergoing staged treatment of MAVM, hemorrhage of an untreated nidus (n = 1), visualization of a new nidus (n = 2), or disappearance of a draining vein (n = 1) occurred. Conclusion: The annual hemorrhage incidence rate for pediatric patients with MAVM approaches the upper range of previously reported hemorrhage rates for solitary AVM. A staged approach to treating MAVM requires close follow-up as changes to the remaining nidi may occur during the latency period. Limitations of this study include its small sample size and reporting bias.