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Research paper
Unruptured intracranial aneurysm follow-up and treatment after morphological change is safe: observational study and systematic review
  1. Renato Gondar1,
  2. Oliver Pascal Gautschi1,
  3. Johanna Cuony1,
  4. Fabienne Perren2,
  5. Max Jägersberg1,
  6. Marco-Vincenzo Corniola1,
  7. Bawarjan Schatlo3,
  8. Granit Molliqaj1,
  9. Sandrine Morel1,
  10. Zsolt Kulcsár4,
  11. Vitor Mendes Pereira5,
  12. Daniel Rüfenacht6,
  13. Karl Schaller1,
  14. Philippe Bijlenga1
  1. 1Neurosurgery Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Medical Center, Geneva, Switzerland
  2. 2Neurology Division, Department of Clinical Neurosciences, Faculty of Medicine, Geneva University Medical Center, Geneva, Switzerland
  3. 3Department of Neurosurgery, University Medicine Göttingen, Georg August University Göttingen, Göttingen, Germany
  4. 4Interventional Neuroradiology Division, Department of Radiology and Medical Informatics, Faculty of Medicine, Geneva University Medical Center, Geneva, Switzerland
  5. 5Neuroimaging Division, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
  6. 6Neuroradiology Division, Hirslanden Clinic, Zürich, Switzerland
  1. Correspondence to Dr Philippe Bijlenga, Service de Neurochirurgie, Département de Neurosciences Cliniques, Hôpitaux Universitaire de Genève, 4 rue Gabrielle-Perret-Gentil, 1211 Genève 14 Switzerland; philippe.bijlenga{at}


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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