Unruptured intracranial aneurysms and the assessment of rupture risk based on anatomical and morphological factors: sifting through the sands of data.

Aneurysmal subarachnoid hemorrhage continues to have high rates of morbidity and mortality for patients despite optimal medical and surgical management. Due to the fact that aneurysmal rupture can be such a catastrophic event, preventive treatment is desirable for high-risk lesions. Given the variability of the literature evaluating unruptured aneurysms regarding basic patient population, clinical practice, and aneurysm characteristics studied, such as size, location, aspect ratio, relationship to the surrounding vasculature, and the aneurysm hemodynamics, a meta-analysis is nearly impossible to perform. This review will instead focus on the various anatomical and morphological characteristics of aneurysms reported in the literature with an attempt to draw broad inferences and serve to highlight pressing questions for the future in our continued effort to improve clinical management of unruptured intracranial aneurysms.

[1]  T. Hori,et al.  Is the Aspect Ratio a Reliable Index for Predicting the Rupture of a Saccular Aneurysm? , 2001, Neurosurgery.

[2]  Didier Martin,et al.  Unruptured intracranial aneurysms--risk of rupture and risks of surgical intervention. , 1998, The New England journal of medicine.

[3]  S. Juvela,et al.  Natural history of unruptured intracranial aneurysms: probability of and risk factors for aneurysm rupture. , 2008, Journal of neurosurgery.

[4]  P. Kailasnath,et al.  ISUIA-II: the need to share more data. , 2004, Surgical neurology.

[5]  D. Nichols,et al.  Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment , 2003, The Lancet.

[6]  J Max Findlay,et al.  The aspect ratio (dome/neck) of ruptured and unruptured aneurysms. , 2003, Journal of neurosurgery.

[7]  V. Seifert,et al.  Size and location of ruptured and unruptured intracranial aneurysms measured by 3-dimensional rotational angiography. , 2006, Surgical neurology.

[8]  Kaoru Kurisu,et al.  MORPHOLOGICAL DIFFERENCES BETWEEN RUPTURED AND UNRUPTURED CASES IN MIDDLE CEREBRAL ARTERY ANEURYSMS , 2008, Neurosurgery.

[9]  H. Michiue,et al.  [Rupture of previously documented asymptomatic unruptured aneurysms--aneurysm size: risk factor for aneurysm rupture]. , 2002, No shinkei geka. Neurological surgery.

[10]  H. Winn,et al.  The long-term outcome in patients with multiple aneurysms. Incidence of late hemorrhage and implications for treatment of incidental aneurysms. , 1983, Journal of neurosurgery.

[11]  J. Sayre,et al.  Anatomical and morphological factors correlating with rupture of intracranial aneurysms in patients referred for endovascular treatment , 1998, Neuroradiology.

[12]  M. Limburg,et al.  Mortality and Morbidity of Surgery for Unruptured Intracranial Aneurysms , 1998 .

[13]  B. Weir,et al.  Patients With Small, Asymptomatic, Unruptured Intracranial Aneurysms and No History of Subarachnoid Hemorrhage Should Be Treated Conservatively , 2005 .

[14]  J. Mocco,et al.  MORPHOLOGY PARAMETERS FOR INTRACRANIAL ANEURYSM RUPTURE RISK ASSESSMENT , 2008, Neurosurgery.

[15]  Akifumi Suzuki,et al.  Long-term follow-up study of unruptured intracranial aneurysms. , 1997, Neurosurgery.

[16]  B. Weir.  Patients with small, asymptomatic, unruptured intracranial aneurysms and no history of subarachnoid hemorrhage should be treated conservatively: against. , 2005, Stroke.

[17]  H. Meng,et al.  Effects of arterial geometry on aneurysm growth: three-dimensional computational fluid dynamics study. , 2004, Journal of neurosurgery.

[18]  G. Rinkel,et al.  Natural history, epidemiology and screening of unruptured intracranial aneurysms. , 2008, Journal of neuroradiology. Journal de neuroradiologie.

[19]  O. Heiskanen.  Risk of bleeding from unruptured aneurysm in cases with multiple intracranial aneurysms. , 1981, Journal of neurosurgery.

[20]  J. Berlin,et al.  Morbidity and mortality from elective surgery for asymptomatic, unruptured, intracranial aneurysms: a meta-analysis. , 1994, Journal of neurosurgery.

[21]  John Huston,et al.  Intracranial Aneurysm Enlargement on Serial Magnetic Resonance Angiography: Frequency and Risk Factors , 2009, Stroke.

[22]  A. Algra,et al.  Case-fatality rates and functional outcome after subarachnoid hemorrhage: a systematic review. , 1997, Stroke.

[23]  Marko Kangasniemi,et al.  Remodeling of Saccular Cerebral Artery Aneurysm Wall Is Associated With Rupture: Histological Analysis of 24 Unruptured and 42 Ruptured Cases , 2004, Stroke.

[24]  N. Kitchen,et al.  IS ASPECT RATIO A RELIABLE PREDICTOR OF INTRACRANIAL ANEURYSM RUPTURE? , 2004, Neurosurgery.

[25]  Masao Sugita,et al.  Size of cerebral aneurysms and related factors in patients with subarachnoid hemorrhage. , 2004, Surgical neurology.

[26]  K. Hashi,et al.  The incidence and treatment of asymptomatic, unruptured cerebral aneurysms. , 1994, Journal of neurosurgery.

[27]  N. Yasui,et al.  Incidence and risk factors for the growth of unruptured cerebral aneurysms: observation using serial computerized tomography angiography. , 2004, Journal of neurosurgery.

[28]  A. Raabe,et al.  Difference in configuration of ruptured and unruptured intracranial aneurysms determined by biplanar digital subtraction angiography , 2003, Acta Neurochirurgica.

[29]  A. Mendelow,et al.  Predicting the risk of rupture of intracranial aneurysms based on anatomical location , 2005, Acta Neurochirurgica.

[30]  N. Yasui,et al.  [Clinical study of growing up aneurysms: report of 25 cases]. , 1991, No shinkei geka. Neurological surgery.

[31]  C. Putman,et al.  Characterization of cerebral aneurysms for assessing risk of rupture by using patient-specific computational hemodynamics models. , 2005, AJNR. American journal of neuroradiology.

[32]  Kaoru Kurisu,et al.  The characteristics of the anterior communicating artery aneurysm complex by three-dimensional digital subtraction angiography , 2006, Neurosurgical Review.

[33]  K. Katada,et al.  Magnitude and Role of Wall Shear Stress on Cerebral Aneurysm: Computational Fluid Dynamic Study of 20 Middle Cerebral Artery Aneurysms , 2004, Stroke.

[34]  M. L. Raghavan,et al.  Three-Dimensional Geometrical Characterization of Cerebral Aneurysms , 2004, Annals of Biomedical Engineering.

[35]  B. Hoh,et al.  BOTTLENECK FACTOR AND HEIGHT‐WIDTH RATIO: ASSOCIATION WITH RUPTURED ANEURYSMS IN PATIENTS WITH MULTIPLE CEREBRAL ANEURYSMS , 2007, Neurosurgery.

[36]  Kazuo Tanishita,et al.  Fluid‐induced wall shear stress in anthropomorphic brain aneurysm models: MR phase‐contrast study at 3 T , 2007, Journal of magnetic resonance imaging : JMRI.

[37]  N. Yasui,et al.  Long-term follow-up study of unruptured intracranial aneurysms. , 1997, Neurosurgery.

[38]  B. Horta,et al.  Risk of rupture in unruptured anterior communicating artery aneurysms: meta-analysis of natural history studies. , 2006, Surgical neurology.

[39]  T. Karrison,et al.  Sizes of ruptured and unruptured aneurysms in relation to their sites and the ages of patients. , 2002, Journal of neurosurgery.

[40]  M. Markl,et al.  In vivo visualization and analysis of 3-D hemodynamics in cerebral aneurysms with flow-sensitized 4-D MR imaging at 3 T , 2008, Neuroradiology.

[41]  Kaoru Kurisu,et al.  Evaluation of relation among aneurysmal neck, parent artery, and daughter arteries in middle cerebral artery aneurysms, by three-dimensional digital subtraction angiography , 2005, Neurosurgical Review.

[42]  Y. Yonekawa,et al.  Patient and aneurysm characteristics in multiple intracranial aneurysms. , 2008, Acta neurochirurgica. Supplement.

[43]  K. Takayama,et al.  A proposed parent vessel geometry-based categorization of saccular intracranial aneurysms: computational flow dynamics analysis of the risk factors for lesion rupture. , 2005, Journal of neurosurgery.

[44]  C M Putman,et al.  Computational fluid dynamics modeling of intracranial aneurysms: effects of parent artery segmentation on intra-aneurysmal hemodynamics. , 2006, AJNR. American journal of neuroradiology.

[45]  Joakim Bjorkdahl,et al.  Unruptured intracranial aneurysms—risk of rupture and risks of surgical intervention. The International Study of Unruptured Intracranial Aneurysms Investigators: , 1999 .

[46]  W Mitchell,et al.  A Review of Size and Location of Ruptured Intracranial Aneurysms , 2001, Neurosurgery.