Article
Is aneurysm growth a surrogate of risk of rupture?
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Authors
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Renato Gondar
- Division of Neurosurgery, Geneva University Hospitals, Geneva Neurosciences Center, Faculty of Medicine, University of Geneva, Switzerland
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Philippe Bijlenga
- Division of Neurosurgery, Geneva University Hospitals, Geneva Neurosciences Center, Faculty of Medicine, University of Geneva, Switzerland
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Karl Schaller
- Division of Neurosurgery, Geneva University Hospitals, Geneva Neurosciences Center, Faculty of Medicine, University of Geneva, Switzerland
| Published: | June 2, 2015 |
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Outline
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Objective: The natural history of small-unruptured incidentally discovered intracranial aneurysms (SUIA) remains unpredictable. Therefore, when asymptomatic, the strategy is not consensual. The aim of this study is to clarify the risk of rupture or morphological changes of SUIA according to their location and identify risk factors associated with growth and rupture.
Method: A prospective cohort of 292 patients (2006-2014) (mean age, 55.1 years; 77.1% women) and 368 SUIA (anterior circulation aneurysms below 7 mm and posterior circulation aneurysms smaller than 4 mm, with absence of previous subarachnoid haemorrhage (SAH)) was collected. Baseline epidemiological data, clinical presentation, risk factors and aneurysm characteristics are specified. Outcome is reported as aneurysm’s shape and size stability versus change or rupture at 6 months, 1, 2 and 5 years after the diagnosis (mean follow-up time of 3.2 years and 1177.6 aneurysm years).
Results: Ophthalmic segment (Oph IC) was the most frequent (n=84, 22.8%), followed by Sylvian bifurcation (MCA bif) (n=82, 22.2%) and Anterior communicating artery (AcoA) (n=54, 14.7%) and the M1 segment of the MCA (M1MCA) (n=41, 11.2%). Mean aneurysm size is 3.6 ± 1.9 mm, with a majority (n=230, 62.5%) inferior to 4 mm. Two unexpected ruptures were observed (M1 and AcoA). The aneurysm growth rate is 2.1% per year. The growth risk odds distribution per location is similar to the rupture risk distribution per location in general population. M1MCA aneurysms have a bigger risk of growth (n=10; 27%; p=0.004), as well as lesions between 4 to 6.9 mm of largest dimension (OR=3.5, 95%CI 1.6-7.5, p<0.001). Together AcoA and posterior circulation lesions (including Posterior communicating artery) showed a trend to growth.
Conclusions: It’s safe to observe small anterior circulation aneurysms, treating them after a morphological change. However, lesions greater than 4mm should be screened more regularly. When classifying aneurysms by location, there’s a trend showing that growing is a normal step before rupture.
