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Cerebral Aneurysms (cerebral + aneurysms)
Selected AbstractsEFNS guideline on neuroimaging in acute stroke.EUROPEAN JOURNAL OF NEUROLOGY, Issue 12 2006Report of an EFNS task force Neuroimaging techniques are necessary for the evaluation of stroke, one of the leading causes of death and neurological impairment in developed countries. The multiplicity of techniques available has increased the complexity of decision making for physicians. We performed a comprehensive review of the literature in English for the period 1965,2005 and critically assessed the relevant publications. The members of the panel reviewed and corrected an initial draft, until a consensus was reached on recommendations stratified according to the European Federation of Neurological Societies (EFNS) criteria. Non-contrast computed tomography (CT) scan is the established imaging procedure for the initial evaluation of stroke patients. However, magnetic resonance imaging (MRI) has a higher sensitivity than CT for the demonstration of infarcted or ischemic areas and depicts well acute and chronic intracerebral hemorrhage. Perfusion and diffusion MRI together with MR angiography (MRA) are very helpful for the acute evaluation of patients with ischemic stroke. MRI and MRA are the recommended techniques for screening cerebral aneurysms and for the diagnosis of cerebral venous thrombosis and arterial dissection. For the non-invasive study of extracranial vessels, MRA is less portable and more expensive than ultrasonography but it has higher sensitivity and specificity for carotid stenosis. Transcranial Doppler is very useful for monitoring arterial reperfusion after thrombolysis, for the diagnosis of intracranial stenosis and of right-to-left shunts, and for monitoring vasospasm after subarachnoid hemorrhage. Currently, single photon emission computed tomography and positron emission tomography have a more limited role in the evaluation of the acute stroke patient. [source] Matrix metalloproteinases 2 and 9 in human atherosclerotic and non-atherosclerotic cerebral aneurysmsEUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2006J. Caird Matrix metalloproteinases 2 and 9 (MMP 2 and -9) have been implicated in the pathogenesis of atherosclerosis and aneurysm formation. The goal of the study was to establish the role of these metalloproteinases in both human atherosclerotic and non-atherosclerotic cerebral aneurysms. Eleven cerebral aneurysms (four atherosclerotic, seven non-atherosclerotic) were immunohistochemically stained for MMP 2 and -9. As controls, atherosclerotic and normal Circle of Willis arteries were similarly immunostained. All specimens were retrieved at autopsy and were paraffin-embedded. In order to evaluate the real MMP 2 and -9 activities, gelatin zymography was also performed in only two available specimens of non-atherosclerotic intracranial aneurysms, because of the relative unavailability of fresh intracranial aneurysm tissue (i.e. reluctance to excise the aneurysm fundus at surgery). Our data establish that MMP 2 and -9 were expressed minimally or not at all in normal Circle of Willis arteries but were strongly expressed in medial smooth muscle cells of atherosclerotic Circle of Willis arteries. In the aneurysm group, both MMP 2 and -9 were strongly expressed in the atherosclerotic aneurysms, but MMP 2 alone was detected in the non-atherosclerotic aneurysms. Zymography revealed a weak enzyme activity correlating to MMP 9 standard recombinant protein. MMP 2 activity was not demonstrated in either specimen. This study shows that the expression of MMP 2 and -9 is associated with atherosclerosis, be it in aneurysmal or non-aneurysmal cerebral vessels but MMP 2 appears to be specifically expressed in aneurysms devoid of atherosclerosis perhaps suggesting a pathogenic role for MMP 2 in the alteration of the extracellular matrix of cerebral arteries during aneurysm formation. [source] Can Computed Tomography Angiography of the Brain Replace Lumbar Puncture in the Evaluation of Acute-onset Headache After a Negative Noncontrast Cranial Computed Tomography Scan?ACADEMIC EMERGENCY MEDICINE, Issue 4 2010Robert F. McCormack MD Abstract Objectives:, The primary goal of evaluation for acute-onset headache is to exclude aneurysmal subarachnoid hemorrhage (SAH). Noncontrast cranial computed tomography (CT), followed by lumbar puncture (LP) if the CT is negative, is the current standard of care. Computed tomography angiography (CTA) of the brain has become more available and more sensitive for the detection of cerebral aneurysms. This study addresses the role of CT/CTA versus CT/LP in the diagnostic workup of acute-onset headache. Methods:, This article reviews the recent literature for the prevalence of SAH in emergency department (ED) headache patients, the sensitivity of CT for diagnosing acute SAH, and the sensitivity and specificity of CTA for cerebral aneurysms. An equivalence study comparing CT/LP and CT/CTA would require 3,000 + subjects. As an alternative, the authors constructed a mathematical probability model to determine the posttest probability of excluding aneurysmal or arterial venous malformation (AVM) SAH with a CT/CTA strategy. Results:, SAH prevalence in ED headache patients was conservatively estimated at 15%. Representative studies reported CT sensitivity for SAH to be 91% (95% confidence interval [CI] = 82% to 97%) and sensitivity of CTA for aneurysm to be 97.9% (95% CI = 88.9% to 99.9%). Based on these data, the posttest probability of excluding aneurysmal SAH after a negative CT/CTA was 99.43% (95% CI = 98.86% to 99.81%). Conclusions:, CT followed by CTA can exclude SAH with a greater than 99% posttest probability. In ED patients complaining of acute-onset headache without significant SAH risk factors, CT/CTA may offer a less invasive and more specific diagnostic paradigm. If one chooses to offer LP after CT/CTA, informed consent for LP should put the pretest risk of a missed aneurysmal SAH at less than 1%. ACADEMIC EMERGENCY MEDICINE 2010; 17:444,451 © 2010 by the Society for Academic Emergency Medicine [source] Blood flow dynamics and fluid,structure interaction in patient-specific bifurcating cerebral aneurysmsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2008Alvaro Valencia Abstract Hemodynamics plays an important role in the progression and rupture of cerebral aneurysms. The current work describes the blood flow dynamics and fluid,structure interaction in seven patient-specific models of bifurcating cerebral aneurysms located in the anterior and posterior circulation regions of the circle of Willis. The models were obtained from 3D rotational angiography image data, and blood flow dynamics and fluid,structure interaction were studied under physiologically representative waveform of inflow. The arterial wall was assumed to be elastic, isotropic and homogeneous. The flow was assumed to be laminar, non-Newtonian and incompressible. In one case, the effects of different model suppositions and boundary conditions were reported in detail. The fully coupled fluid and structure models were solved with the finite elements package ADINA. The vortex structure, pressure, wall shear stress (WSS), effective stress and displacement of the aneurysm wall showed large variations, depending on the morphology of the artery, aneurysm size and position. The time-averaged WSS, effective stress and displacement at the aneurysm fundus vary between 0.17 and 4.86,Pa, 4.35 and 170.2,kPa and 0.16 and 0.74,mm, respectively, for the seven patient-specific models of bifurcating cerebral aneurysms. Copyright © 2008 John Wiley & Sons, Ltd. [source] Efficient estimation of three-dimensional curves and their derivatives by free-knot regression splines, applied to the analysis of inner carotid artery centrelinesJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 3 2009Laura M. Sangalli Summary., We deal with the problem of efficiently estimating a three-dimensional curve and its derivatives, starting from a discrete and noisy observation of the curve. This problem is now arising in many applicative contexts, thanks to the advent of devices that provide three-dimensional images and measures, such as three-dimensional scanners in medical diagnostics. Our research, in particular, stems from the need for accurate estimation of the curvature of an artery, from image reconstructions of three-dimensional angiographies. This need has emerged within the AneuRisk project, a scientific endeavour which aims to investigate the role of vessel morphology, blood fluid dynamics and biomechanical properties of the vascular wall, on the pathogenesis of cerebral aneurysms. We develop a regression technique that exploits free-knot splines in a novel setting, to estimate three-dimensional curves and their derivatives. We thoroughly compare this technique with a classical regression method, local polynomial smoothing, showing that three-dimensional free-knot regression splines yield more accurate and efficient estimates. [source] Comparative velocity investigations in cerebral arteries and aneurysms: 3D phase-contrast MR angiography, laser Doppler velocimetry and computational fluid dynamicsNMR IN BIOMEDICINE, Issue 8 2009Dorothea I. Hollnagel Abstract In western populations, cerebral aneurysms develop in approximately 4% of humans and they involve the risk of rupture. Blood flow patterns are of interest for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient. Velocity mapping with phase-contrast magnetic resonance angiography (PC-MRA) is a non-invasive method for performing in vivo measurements on blood velocity. Several hemodynamic properties can either be derived directly from these measurements or a flow field with all its parameters can be simulated on the basis of the measurements. For both approaches, the accuracy of the PC-MRA data and subsequent modeling must be validated. Therefore, a realistic transient flow field in a well-defined patient-specific silicone phantom was investigated. Velocity investigations with PC-MRA in a 3,Tesla MR scanner, laser Doppler velocimetry (LDV) and computational fluid dynamics (CFD) were performed in the same model under equal flow conditions and compared to each other. The results showed that PC-MRA was qualitatively similar to LDV and CFD, but showed notable quantitative differences, while LDV and CFD agreed well. The accuracy of velocity quantification by PC-MRA was best in straight artery regions with the measurement plane being perpendicular to the primary flow direction. The accuracy decreased in regions with disturbed flow and in cases where the measurement plane was not perpendicular to the primary flow. Due to these findings, it is appropriate to use PC-MRA as the inlet and outlet conditions for numerical simulations to calculate velocities and shear stresses in disturbed regions like aneurysms, rather than derive these values directly from the full PC-MRA measured velocity field. Copyright © 2009 John Wiley & Sons, Ltd. [source] Multiple cerebral aneurysms as delayed complication of left cardiac myxoma: a case report and reviewACTA NEUROLOGICA SCANDINAVICA, Issue 6 2005M. Sabolek Left cardiac myxoma and also consecutive embolization into the brain is well documented, whereas the association of myxomas with multiple fusiform cerebral aneurysms is rare. We analyze 33 previously reported patients and present a case of a 43-year-old woman with multiple cerebral infarctions 2 years after resection of a recurrent myxoma in the left atrium. Cerebral angiography displayed multiple fusiform aneurysms of several cerebral arteries, including a giant aneurysm of the basilar artery. Serum level of interleukin-6 (IL-6) was highly elevated. The clinical, radiological and pathological features of these aneurysms are summarized. The pathogenesis, including the role of IL-6 in the formation of myxomatous aneurysms, is discussed. [source] | ||||||||||