Long-term outcomes in pediatric brain AVMs: beyond radiological cure

Background: Brain AVMs are typically considered cured after angiographic confirmation of nidus obliteration. However, in pediatric patients, recurrence can occur many years later, underscoring the need for long-term clinical surveillance. Event-free survival (EFS) represents a complementary, exploratory metric of therapeutic success that captures time-dependent morbidity. Methods: We retrospectively analyzed 46 pediatric patients with brain arteriovenous malformations (bAVMs) treated between 2013 and 2025. Clinical data, bAVM characteristics, treatment strategies, and outcomes were systematically collected. EFS was defined as the absence of clinically significant neurological complications throughout follow-up, whether early or late, and attributable to bAVM natural history or treatment-related effects. Kaplan–Meier survival analysis was performed to assess EFS by radiological cure status. Long-term functional outcomes were evaluated using the modified Rankin Scale (mRS). Results: Median age was 9.8 years; 78.3 % presented with hemorrhage. Radiological cure was achieved in 77.5 % of patients completing treatment. At final follow-up (median 56.5 months; 64 months in the EFS subset), 87 % had a favorable outcome (mRS ≤2). Clinical events occurred both early (≤30 days) and late (>30 days), with late events predominating. Over 30 % of patients with confirmed radiological cure experienced events. Long-term events were not associated with hemorrhagic onset, nor with urgent surgical treatment, suggesting they are not merely acute-phase complications. Two angiographic recurrences occurred after more than 9 years. Conclusion: Event-free survival (EFS) is a complementary metric that reflects long-term morbidity from both natural history and treatments, highlighting the persistence of events beyond radiological cure and supporting extended follow-up in pediatric AVMs.