Clinical Neuroradiology

, Volume 28, Issue 2, pp 183–189 | Cite as

Growth of Untreated Unruptured Small-sized Aneurysms (≺7mm): Incidence and Related Factors

  • Hyun Ho Choi
  • Young Dae ChoEmail author
  • Jin Pyeong Jeon
  • Dong Hyun Yoo
  • Jusun Moon
  • Jeongjun Lee
  • Hyun-Seung Kang
  • Won-Sang Cho
  • Jeong Eun Kim
  • Li Zhang
  • Moon Hee Han
Original Article



The need to treat small (<7 mm) unruptured aneurysms is still controversial, despite data collected through several large cohort studies. Such lesions typically are incidental findings, usually followed for potential growth through serial imaging. For this study, growth estimates for untreated unruptured small-sized aneurysms were generated, examining incidence and related risk factors.


A cohort of 135 consecutive patients harboring 173 untreated unruptured small-sized aneurysms (<7 mm) was subjected to extended monitoring (mean, 73.1 ± 30.0 months). Growth was defined as a 1-mm increase at minimum in one or more aneurysmal dimensions or as a significant change in shape. Medical records and radiological data were reviewed. Cumulative growth rate and related risk factors were analyzed via Cox proportional hazards regression and Kaplan-Meier product-limit estimator.


A total of 28 aneurysms (16.2%) displayed growth during continued surveillance (1054.1 aneurysm-years). The annual growth rate was 2.65% per aneurysm-year, with 15 surfacing within 60 months and 13 after 60 months. Multivariate analysis indicated that bifurcation type was the sole significant risk factor (hazard ratio HR = 7.64; p < 0.001) in terms of growth. Cumulative survival rates without growth were significantly lower in subjects with bifurcation aneurysms than with side-wall aneurysms (p < 0.001). During the follow-up period, one patient suffered a subarachnoid hemorrhage and then aneurysm growth was detected.


Most (83.8%) untreated unruptured small-sized aneurysms (<7 mm) remained stable and devoid of growth in long-term follow-up. Because bifurcation aneurysms were prone to eventual growth, careful long-term monitoring at regular intervals is advised if left untreated.


Aneurysm Small Unruptured Growth Follow up 


Compliance with ethical guidelines

Conflict of interest

H.H. Choi, Y.D. Cho, J.P. Jeon, D.H. Yoo, J. Moon, J. Lee, H.-S. Kang, W.-S Cho, J.E. Kim, L. Zhang and M.H. Han declare that they have no competing interests.

Ethical standards

All studies on humans described in this manuscript were carried out with approval of the responsible ethics committee and in accordance with national law and the Helsinki Declaration from 1964 (in its current revised form). The requirement to obtain written informed consent for study participation was waived.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Hyun Ho Choi
    • 1
  • Young Dae Cho
    • 2
    Email author
  • Jin Pyeong Jeon
    • 3
  • Dong Hyun Yoo
    • 2
  • Jusun Moon
    • 2
  • Jeongjun Lee
    • 4
  • Hyun-Seung Kang
    • 4
  • Won-Sang Cho
    • 4
  • Jeong Eun Kim
    • 4
  • Li Zhang
    • 5
  • Moon Hee Han
    • 2
    • 4
  1. 1.Department of Neurosurgery, Dongkuk University HospitalDongkuk University College of MedicineIlsanKorea (Republic of)
  2. 2.Department of Radiology, Seoul National University HospitalSeoul National University College of MedicineSeoulKorea (Republic of)
  3. 3.Department of NeurosurgeryHallym University College of MedicineChuncheonKorea (Republic of)
  4. 4.Department of Neurosurgery, Seoul National University HospitalSeoul National University College of MedicineSeoulKorea (Republic of)
  5. 5.Department of NeurologyChina-Japan Union Hospital of Jilin UniversityChangchunChina

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