Background The management of small unruptured incidentally discovered intracranial aneurysms (SUIAs) is still controversial. The aim of this study is to assess the safety of a management protocol of SUIAs, where selected cases with SUIAs are observed and secured only if signs of instability (growth) are documented.
Methods A prospective consecutive cohort of 292 patients (2006–2014) and 368 SUIAs (anterior circulation aneurysms (ACs) smaller than 7 mm and posterior circulation aneurysms smaller than 4 mm without previous subarachnoid haemorrhage) was observed (mean follow-up time of 3.2 years and 1177.6 aneurysm years). Factors associated with aneurysm growth were systematically reviewed from the literature.
Results The aneurysm growth probability was 2.6±0.1% per year. The rate of unexpected aneurysm rupture before treatment was 0.24% per year (95% CI 0.17% to 2.40%). The calculated rate of aneurysm rupture after growth was 6.3% per aneurysm-year (95% CI 1% to 22%). Aneurysms located in the posterior circulation and aneurysms with lobulation were more likely to grow. Females or patients suffering hypertension were more likely to have an aneurysm growing. The probability of aneurysms growth increased with the size of the dome and was proportional to the number of aneurysms diagnosed in a patient.
Conclusions It is safe to observe patients diagnosed with SUIAs using periodic imaging. Intervention to secure the aneurysm should be performed after growth is observed.
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Contributors RG contributed to the analysis and interpretation of data, and drafting and revising of the manuscript for intellectual content. OPG participated in the interpretation and revising of the manuscript for intellectual content. JC and GM contributed to the analysis and interpretation of data. FP contributed to the analysis and interpretation of data, and revising of the manuscript for intellectual content. MJ, M-VC, BS, SM, ZK and KS were responsible for the revising of the manuscript for intellectual content. VMP and DR contributed to the conceptualisation of the study, and revising of the manuscript for intellectual content. PB contributed to the design and conceptualisation of the study, analysis and interpretation of the data, and drafting and revising of the manuscript for intellectual content.
Funding Study was performed within the framework of the AneuX project supported by SystemsX.ch, and evaluated by the Swiss National Science Foundation (2014/261). The study was sponsored by the SwissNeuroFoundation. We acknowledge the contributions of the Clinical Research Center, University Hospital and Faculty of Medicine, Geneva and thank Nathalie Isidor for her strong support.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Geneva CCER 07-056 (local ethics committee).
Provenance and peer review Not commissioned; externally peer reviewed.