Risk Factors for Growth of Unruptured Intracranial Aneurysms: Follow-up Study by Serial 0.5–T Magnetic Resonance Angiography

OBJECTIVE: The independent risk factors for aneurysm growth were retrospectively investigated in 130 patients with unruptured aneurysms who were followed up by 0.5-T serial magnetic resonance angiography with stereoscopic images. METHODS: Age, sex, site of aneurysm, size of aneurysm, multiplicity of aneurysms, type of circle of Willis, length of follow-up period, cerebrovascular event, hypertension, diabetes, hyperlipidemia, smoking habit, and family history of subarachnoid hemorrhage were investigated using multiple logistic analysis. RESULTS: Fourteen patients (16 aneurysms) among the 130 patients (159 aneurysms) showed aneurysm growth (10.8%) during follow-up of 10 to 69 months (mean 29.3 +/- 10.5 mo). Multiple logistic analysis disclosed that location on the middle cerebral artery (odds ratio [OR] 0.08, P < 0.01), multiplicity of aneurysms (OR 68.5, P < 0.01), aneurysm size of 5 mm or larger (OR 1.17, P = 0.05), and family history of subarachnoid hemorrhage (OR 10.9, P < 0.01) were independent risk factors. CONCLUSION: Location on the middle cerebral artery, multiplicity, aneurysm size of 5 mm or larger, and family history of subarachnoid hemorrhage are independent risk factors for aneurysm growth. These results may help to determine the treatment choice for unruptured aneurysms.