J Korean Neurosurg Soc.  2016 Jan;59(1):11-16. 10.3340/jkns.2016.59.1.11.

Natural History of Unruptured Intracranial Aneurysms : A Retrospective Single Center Analysis

• Byoun HS
• Huh W
• Oh CW
• Bang JS
• Hwang G
• Kwon OK

• KMID: 2152913
• DOI: http://doi.org/10.3340/jkns.2016.59.1.11

Abstract

OBJECTIVE
We conducted a retrospective cohort study to elucidate the natural course of unruptured intracranial aneurysms (UIAs) at a single institution.
METHODS
Data from patients diagnosed with UIA from March 2000 to May 2008 at our hospital were subjected to a retrospective analysis. The cumulative and annual aneurysm rupture rates were calculated. Additionally, risk factors associated with aneurysmal rupture were identified.
RESULTS
A total of 1339 aneurysms in 1006 patients met the inclusion criteria. During the follow-up period, 685 aneurysms were treated before rupture via either an open surgical or endovascular procedure. Six hundred fifty-four UIAs were identified and not repaired during the follow-up period. The mean UIA size was 4.5+/-3.2 mm, and 86.5% of the total UIAs had a largest dimension <7 mm. Among these UIAs, 18 ruptured at a median of 1.6 years (range : 27 days to 9.8 years) after day 0. The annual rupture risk during a 9-year follow-up was 1.00%. A multivariate Cox proportional hazards analysis revealed that the aneurysm size and a history of subarachnoid hemorrhage (SAH) were statistically significant risk factors for rupture. For an aneurysms smaller than 7 mm in the absence of a history of SAH, the annual rupture risk was 0.79%.
CONCLUSION
In our study, the annual rupture risk for UIAs smaller than 7 mm in the absence of a history of SAH was higher than that of Western populations but similar to that of the Japanese population.

Keyword

Natural history; Intracranial aneurysms; Rupture rate; Risk factors

MeSH Terms

Aneurysm
Asian Continental Ancestry Group
Cohort Studies
Endovascular Procedures
Follow-Up Studies
Humans
Intracranial Aneurysm*
Natural History*
Retrospective Studies*
Risk Factors
Rupture
Subarachnoid Hemorrhage

Figure

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  Fig. 1 The probability of aneurysm rupture calculated by the Kaplan-Meier method. The log-rank test revealed the statistical differences of the probabilities of aneurysm ruptures according to smoking history (A), previous episode of SAH (B), and aneurysm size (7 mm) (C). Kaplan-Meier curves showing the probability of aneurysm rupture.

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