Treatment-related complications of intracranial aneurysms smaller than 5 mm: A multicenter analysis of 1,519 cases in Latin America

Background: Small (<5 mm) intracranial aneurysms present a therapeutic challenge due to their low annual rupture risk and uncertainties regarding procedure-related morbidity. Evidence from Latin America remains limited. Methods: We conducted a retrospective multicenter observational study including 1,519 patients treated between 2017 and 2023 in eight referral centers across five Latin American countries. Demographic, clinical, morphological, and treatment-related variables were analyzed. Logistic regression was used to identify independent predictors of treatment-related complications. Results: e overall complication rate was 6%. Surgical treatment showed higher crude complication rates (11%) compared with endovascular therapy (6%), largely reflecting a greater proportion of ruptured aneurysms. Independent predictors of treatment-related complications were a history of aneurysmal subarachnoid hemorrhage (odds ratio [OR] = 5.03), intraparenchymal hematoma before treatment (OR = 3.56), and ruptured aneurysm status (OR = 2.13). Complications were associated with higher mortality (31% vs. 7%; P < 0.001) and worse 1-year outcomes (Modified Rankin Scale 3–6: 41% vs. 12%; P < 0.001). Conclusion: In this first regional multicenter series, treatment of small intracranial aneurysms in Latin America demonstrated low complication rates and favorable safety profiles for both surgical and endovascular techniques. e predictors identified may support clinical decision-making and improve prognostic assessment. Keywords: Complications, Endovascular procedures, Intracranial aneurysm, Neurosurgical procedures, Subarachnoid hemorrhage