[Analysis of Rupture during Follow-up of Unruptured Aneurysm]

To elucidate clinical aspects of ruptured aneurysms, we retrospectively investigated associations between risk factors and ruptured and unruptured cases during conservative management.

Two hundred and twenty-nine patients with 291 unruptured cerebral aneurysms treated between 2000 and 2012 were analyzed. Mean duration of observation was 62 months (1183.4 person-years). We investigated the following six risk factors: history of subarachnoid hemorrhage;multiplicity;location of aneurysms;aneurysm size ≤5mm;bleb or irregular forms;and follow-up period <1 year.

Twenty-two aneurysms in 22 patients (19 women;86.4%) ruptured during this study. The annual rate of rupture was 1.86%. In ruptured cases, mean age was 66.7 years. According to univariate analysis, aneurysm size≥5mm(p=0.000), bleb or irregular form(p=0.006)and duration of observation<1 year (p =0.000) were significantly associated with aneurysmal rupture. In multivariate analysis of these factors, aneurysm size≥5mm(p =0.0188;odds ratio(OR), 3.4;95% confidence interval (CI), 1.2-9.7) and duration of observation<1 year (p=0.006;OR, 5.0;95% CI, 1.6-14.9) represented independent risk factors for aneurysm rupture.

The results of this study were almost the same as those of the UCAS Japan study. In addition, duration of observation <1 year was a risk factor for aneurysm rupture. When we decide on surgical treatment after considering factors such as aneurysm size, form, and surgical risk, surgery should be performed as soon as possible.