Bleeding risk of small intracranial aneurysms in a population treated in a reference center

ABSTRACT

Large multicenter studies have shown that small intracranial aneurysms are associated with a minimal risk of bleeding. Nevertheless, other large series have shown that most ruptured aneurysms are, in fact, the smaller ones. In the present study, we questioned whether small aneurysms are indeed not dangerous.

Methods: We enrolled 290 patients with newly-diagnosed aneurysms at our institution over a six-year period (43.7% ruptured). We performed multivariate analyses addressing epidemiological issues, cardiovascular diseases, and three angiographic parameters (largest aneurysm diameter, neck diameter and diameter of the nutrition vessel). Risk estimates were calculated using a logistic regression model. Aneurysm size parameters were stratified according to receiver operating characteristic (ROC) curves. Finally, we calculated odds ratios for rupture based on the ROC analysis.

Results: The mean largest diameter for the ruptured versus unruptured groups was 13.3 ± 1.7 mm versus 22.2 ± 2.2 mm (p < 0.001). Multivariate analysis revealed a positive correlation between rupture and arterial hypertension (p < 0.001) and an inverse correlation with all three angiographic measurements (all p < 0.01). Aneurysms from the anterior cerebral artery bled more often (p < 0.05). According to the ROC curves, at the largest diameter of 15 mm, the sensitivity and specificity to predict rupture were 83% and 36%, respectively. Based on this stratification, we calculated the chance of rupture for aneurysms smaller than 15 mm as 46%, which dropped to 25% for larger aneurysms.

Conclusion: In the population studied at our institution, small aneurysms were more prone to bleeding. Therefore, the need for intervention for small aneurysms should not be overlooked.

RESUMO

Grandes estudos multicêntricos demostram que aneurismas intracranianos pequenos são associados a risco de sangramento mínimo. Outras grandes séries têm evidenciado que aneurismas rotos são em sua maioria os pequenos. Neste estudo questionamos até que ponto os aneurismas pequenos não são perigosos.

Métodos: Avaliamos 290 novos casos de aneurismas tratados em nossa instituição durante 6 anos (43,7% rotos). Realizamos análises multivariadas com aspectos epidemiológicos dos pacientes, doenças cardiovasculares e três parâmetros angiográficos: maior diâmetro, diâmetro do colo e diâmetro do vaso nutridor do aneurisma. Estimativas de risco foram calculadas utilizando-se modelo de regressão logística. Parâmetros do tamanho aneurismático foram estratificados de acordo com curvas ROC. Também calculamos a razão de chances (odds ratios) de ruptura baseadas nas análises das curvas ROC.

Resultados: O maior diâmetro médio para os grupos de aneurismas rotos e não-rotos foi 13.3 ± 1.7mm e 22.2 ± 2.2 (p < 0.001). Análises multivariadas revelaram uma correlação positiva entre ruptura aneurismática e hipertensão arterial (p < 0.001) e uma correlação inversa entre ruptura e as três medidas angiográficas (p < 0.01). Aneurismas da artéria cerebral anterior foram os que mais sangraram (p < 0.05). Análises das curvas ROC demonstram que no maior diâmetro de 15mm, a sensibilidade e especificidade para se predizer ruptura são de 83% e 36%. Baseando-se nessas estratificações, calculamos uma chance de ruptura para aneurismas menores de 15mm de 46% e de 25% para aneurismas maiores.

Conclusão: Na população estudada, aneurismas pequenos são mais propensos a romper. Desta forma, a necessidade de intervenção para aneurismas pequenos não deve ser relevada.

Keywords:

Intracranial aneurysm - rupture

Palavras-chave:

Aneurisma intracraniano - ruptura

Publication History

Received: 28 August 2018

Accepted: 05 February 2019

Article published online:
16 August 2023

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