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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Department of Neurosurgery, Dongkuk University Hospital, Dongkuk University College of Medicine, Ilsan, Korea (Republic of).
Hyun Ho
HH
Choi
Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, 28 Yongon-Dong, Jongno-Gu, 110-744, Seoul, Korea (Republic of). aronnn@naver.com.
Young Dae
YD
Cho
Department of Neurosurgery, Hallym University College of Medicine, Chuncheon, Korea (Republic of).
Jin Pyeong
JP
Jeon
Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, 28 Yongon-Dong, Jongno-Gu, 110-744, Seoul, Korea (Republic of).
Dong Hyun
DH
Yoo
Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, 28 Yongon-Dong, Jongno-Gu, 110-744, Seoul, Korea (Republic of).
Jusun
J
Moon
Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea (Republic of).
Jeongjun
J
Lee
Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea (Republic of).
Hyun-Seung
HS
Kang
Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea (Republic of).
Won-Sang
WS
Cho
Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea (Republic of).
Jeong Eun
JE
Kim
Department of Neurology, China-Japan Union Hospital of Jilin University, Changchun, China.
Li
L
Zhang
Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, 28 Yongon-Dong, Jongno-Gu, 110-744, Seoul, Korea (Republic of).|Department of Neurosurgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea (Republic of).
Moon Hee
MH
Han
D000368:Aged; D017542:Aneurysm, Ruptured; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000150:complications / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000209:etiology*
Aneurysm; Follow up; Growth; Small; Unruptured