Clinical, radiological, and flow-related risk factors for growth of untreated, unruptured intracranial aneurysms.
OBJECTIVE
Unruptured intracranial aneurysms are frequently followed to monitor aneurysm growth. We studied the yield of follow-up imaging and analyzed risk factors for aneurysm growth.


METHODS
We included patients with untreated, unruptured intracranial aneurysms and ≥6 months of follow-up imaging from 2 large prospectively collected databases. We assessed the proportion of patients with aneurysm growth and performed univariable and multivariable Cox regression analyses to calculate hazard ratios with corresponding 95% confidence intervals (CI) for clinical and radiological risk factors for aneurysm growth. We repeated these analyses for the subset of small (<7 mm) aneurysms.


RESULTS
Fifty-seven (12%) of 468 aneurysms in 363 patients grew during a median follow-up of 2.1 years (total follow-up, 1372 patient-years). In multivariable analysis, hazard ratios for aneurysm growth were as follows: 1.1 (95% CI, 1.0-1.2) per each additional mm of initial aneurysm size; 2.7 (95% CI, 1.2-6.4) for dome > neck ratio; 2.1 (95% CI, 0.9-4.9) for location in the posterior circulation; and 2.0 (95% CI, 0.8-4.8) for multilobarity. In the subset of aneurysms <7 mm, 37 of 403 (9%) enlarged. In multivariable analysis, hazard ratios for aneurysm growth were 1.1 (95% CI, 0.8-1.5) per each additional mm of initial aneurysm size, 2.2 (95% CI, 1.0-4.8) for smoking, 2.9 (95% CI, 1.0-8.5) for multilobarity, 2.4 (95% CI, 1.0-5.8) for dome/neck ratio, and 2.0 (95% CI, 0.6-7.0) for location in the posterior circulation.


CONCLUSIONS
Initial aneurysm size, dome/neck ratio, and multilobarity are risk factors for aneurysm growth. Cessation of smoking is pivotal because smoking is a modifiable risk factor for growth of small aneurysms.
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.). A.S.E.Bor@umcutrecht.nl.
A Stijntje E
AS
Bor
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Andreas T
AT
Tiel Groenestege
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Karel G
KG
terBrugge
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Ronit
R
Agid
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Birgitta K
BK
Velthuis
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Gabriel J E
GJ
Rinkel
From the Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands (A.S.E.B., A.T.T.G., G.J.E.R.); Division of Neuroradiology, Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada (A.T.T.G., K.G.t., R.A.); Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands (B.K.V.); and Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands (M.J.H.W.).
Marieke J H
MJ
Wermer
D002533:Cerebral Angiography; D015897:Comorbidity; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000473:pathology; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000453:epidemiology*; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed
follow-up studies; intracranial aneurysm; subarachnoid hemorrhage