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

Abstract

<jats:p>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 metaanalysis 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.</jats:p>

Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage

“…32 (4) Aneurysm size Ͼ7 mm has been shown to be a risk factor for rupture. 33 (5) There does not appear to be an increased risk of aSAH in pregnancy, delivery, and puerperium. 34,35 Inflammation appears to play an important role in the pathogenesis and growth of intracranial aneurysms.…”

“…Several characteristics of aneurysm morphology (such as a bottleneck shape 46 and the ratio of size of aneurysm to parent vessel 47,48 ) have been associated with rupture status, but how these might be applied to individual patients to predict future aneurysmal rupture is still unclear. 33 Variability within each patient is unpredictable at this time, but such intraindividual variability markedly changes the risk of aneurysm detection and rupture and may attenuate the benefits of routine screening in high-risk patients. 49 Given such uncertainties, younger age, longer life expectancy, and higher rate of rupture all make treatment of unruptured aneurysms more likely to be cost-effective and reduce morbidity and mortality.…”

Management of incidentally discovered intracranial vascular abnormalities

“…It is currently accepted that the risk of hemorrhage is high when the aspect ratio is greater than 3. 78 Active cigarette smoking has been shown to be an important risk factor for aneurysm growth 39,66 and therefore should be considered in the decision whether to treat or watch an aneurysm. 39 Patients should also be strongly advised to quit smoking.…”

Improved Microsurgical Creation of Venous Pouch Arterial Bifurcation Aneurysms in Rabbits

“…The aneurysm aspect ratio (length/neck width) was calculated. 25 Additionally, the distance of the neck plane center from the contour of the parent artery was measured (Fig 2B) to determine the Ohshima-type bifurcation aneurysm. 26 All animals showing a patent aneurysm at follow-up were not killed but were included in ongoing experiments at the Department of Clinical Research of the University of Berne.…”