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Radiological surveillance of small unruptured intracranial aneurysms: a systematic review, meta-analysis, and meta-regression of 8428 aneurysms

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Abstract

With the widespread use of imaging techniques, the possibility that an asymptomatic unruptured intracranial aneurysm (UIA) is detected has increased significantly. There is no established consensus regarding follow-up, duration, and frequency of such imaging surveillance. The objectives of this study include assessing the growth rate and rupture risk of small (less than 7mm) UIAs, identifying associated risk factors and providing an aneurysm surveillance protocol in appropriately selected patients. Systematic searches of Medline, Embase, and Cochrane Central were undertaken from database inception to March 2020 for published studies reporting the growth and rupture risks of small UIAs. Twenty-one studies reporting 8428 small UIAs were included in our meta-analysis. The pooled mean age was 61 years (95% CI: 55–67). The mean follow-up period for growth and rupture ranged from 11 to 108 months, with the pooled mean follow-up period across 14 studies being 42 months (95% CI: 33–51). Pooled overall growth rate was 6.0% (95% CI: 3.8–8.7). Pooled growth rates for aneurysms < 5mm and < 3 mm were 5.2% (95% CI: 3.0–7.9) and 0.8% (95% CI: 0.0–6.1), respectively. Pooled overall rupture rate was 0.4% (95% CI: 0.2–0.7). From the meta-regression analysis, having multiple aneurysms, smoking, hypertension, and personal history of SAH did not significantly predict growth, and a personal history of SAH, smoking, hypertension, and multiple aneurysms were not statistically significant predictors of rupture. Our findings suggest that small UIAs have low growth and rupture rates and very small UIAs have little or no risk for rupture. In the setting of incidental small UIAs, patients with multiple and/or posterior circulation aneurysms require more regular radiological monitoring.

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Author notes

  1. Keng Siang Lee and John J. Y. Zhang are co-first authors and contributed equally to this manuscript.

Authors and Affiliations

  1. Bristol Medical School, University of Bristol, Bristol, UK

    Keng Siang Lee

  2. Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore

    John J. Y. Zhang

  3. Department of Neurosurgery, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, PR2 9HT, UK

    Andrew Folusho Alalade, Nicholas Park, Gareth Roberts & Nihal T. Gurusinghe

  4. Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA

    Roanna Vine & Giuseppe Lanzino

  5. Department of Radiology, Mayo Clinic, Rochester, MN, USA

    Roanna Vine & Giuseppe Lanzino

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Correspondence to Andrew Folusho Alalade.

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Lee, K.S., Zhang, J.J.Y., Alalade, A.F. et al. Radiological surveillance of small unruptured intracranial aneurysms: a systematic review, meta-analysis, and meta-regression of 8428 aneurysms. Neurosurg Rev 44, 2013–2023 (2021). https://doi.org/10.1007/s10143-020-01420-1

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