Blog
About

0
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      Acute MRI Changes in Progressive Ischemic Stroke

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background and Purpose: Neurological deterioration following acute stroke is common and associated with increased morbidity and mortality. The underlying pathophysiological mechanisms are not fully understood, and it is difficult to predict which patients are at risk of deterioration. Our study aimed to assess if acute MRI findings could be used for the prediction of stroke in progression (SIP). Methods: Prospectively 41 patients, 13 with lacunar infarcts and 28 with territorial infarcts, were admitted to an acute stroke unit within 24 h of stroke onset (median 11 h, range 3– 22). Diffusion-weighted imaging (DWI), perfusion-weighted imaging and magnetic resonance angiography were performed 3 times, immediately after clinical evaluation, on day 7 and after 3 months. Clinical neurological assessments were performed every 2 h during the first 24 h and once daily from day 2 to 7. SIP was defined as a permanent decrease of ≧3 Scandinavian Stroke Scale (SSS) points for speech or ≧2 SSS points for consciousness or ≧2 SSS points for limb strength, when assessed at baseline compared to the day after admission and daily during the following week. Patients were followed up on day 90 and assessed using the modified Rankin Scale, Barthel Index and SSS score. Patients with and without SIP were compared using both clinical and MRI data obtained on admission, on day 7 and after 3 months. Results: Fifteen patients (37%) developed SIP. Increased DWI lesion volume on day 7 in all strokes was associated with SIP (χ<sup>2</sup>, p = 0.005). All lacunar infarcts with a DWI volume >1.5 cm<sup>3</sup> at baseline (4 patients) developed SIP (p < 0.005). Patients with territorial infarcts and SIP had lower baseline SSS scores with severer symptoms than non-SIP patients (p ≤ 0.05). Despite trends in MRI differences at baseline, only the baseline SSS score in patients with territorial infarcts remained an independent predictor of SIP, when using a logistic regression model (p < 0.05). Conclusions: These findings suggest that SIP is due to growth of the lesion volume from baseline to day 7. In patients with lacunar infarcts, there was an association between initial lesion size and risk of developing SIP. However, for territorial infarcts, baseline SSS was found to be the best individual predictor of SIP and clinical outcome.

          Related collections

          Most cited references 16

          • Record: found
          • Abstract: found
          • Article: not found

          High resolution measurement of cerebral blood flow using intravascular tracer bolus passages. Part I: Mathematical approach and statistical analysis.

          The authors review the theoretical basis of determination of cerebral blood flow (CBF) using dynamic measurements of nondiffusible contrast agents, and demonstrate how parametric and nonparametric deconvolution techniques can be modified for the special requirements of CBF determination using dynamic MRI. Using Monte Carlo modeling, the use of simple, analytical residue models is shown to introduce large errors in flow estimates when actual, underlying vascular characteristics are not sufficiently described by the chosen function. The determination of the shape of the residue function on a regional basis is shown to be possible only at high signal-to-noise ratio. Comparison of several nonparametric deconvolution techniques showed that a nonparametric deconvolution technique (singular value decomposition) allows estimation of flow relatively independent of underlying vascular structure and volume even at low signal-to-noise ratio associated with pixel-by-pixel deconvolution.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Viability thresholds and the penumbra of focal ischemia.

             K Hossmann (1994)
            The classic concept of the viability thresholds of ischemia differentiates between two critical flow rates, the threshold of electrical failure and the threshold of membrane failure. These thresholds mark the upper and lower flow limits of the ischemic penumbra which is thought to suffer only functional but not structural injury. Recent studies of the functional and metabolic disturbances suggest a more complex pattern of thresholds. At declining flow rates, protein synthesis is inhibited at first (at a threshold of about 0.55 ml/gm/min), followed by a stimulation of anaerobic glycolysis (at 0.35 ml/gm/min), the release of neurotransmitters and the beginning disturbance of energy metabolism (at about 0.20 ml/min), and finally the anoxic depolarization (< 0.15 ml/gm/min). The penumbra, as defined by the classic flow thresholds, does not remain viable for extended periods. Since viability of the tissue requires maintenance of energy-dependent metabolic processes, penumbra is redefined as a region of constrained blood supply in which the energy metabolism is preserved. Imaging of the penumbra by combining autoradiographic cerebral blood flow measurements with bioluminescent images of adenosine triphosphate (ATP) demonstrates a gradual expansion of the infarct core (in which ATP is depleted) into the penumbra until, after a few hours, the penumbra has disappeared. It is suggested that the limited survival of the penumbra is due to periinfarct depolarizations, which result in repeated episodes of tissue hypoxia, because the increased metabolic workload is not coupled to an adequate increase of collateral blood supply. This explains pharmacological suppression of periinfarct depolarizations lowering the threshold of metabolic disturbances and reducing the volume of the ischemic infarct.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The Desmoteplase in Acute Ischemic Stroke Trial (DIAS): a phase II MRI-based 9-hour window acute stroke thrombolysis trial with intravenous desmoteplase.

              Most acute ischemic stroke patients arrive after the 3-hour time window for recombinant tissue plasminogen activator (rtPA) administration. The Desmoteplase In Acute Ischemic Stroke trial (DIAS) was a dose-finding randomized trial designed to evaluate the safety and efficacy of intravenous desmoteplase, a highly fibrin-specific and nonneurotoxic thrombolytic agent, administered within 3 to 9 hours of ischemic stroke onset in patients with perfusion/diffusion mismatch on MRI. DIAS was a placebo-controlled, double-blind, randomized, dose-finding phase II trial. Patients with National Institute of Health Stroke Scale (NIHSS) scores of 4 to 20 and MRI evidence of perfusion/diffusion mismatch were eligible. Of 104 patients, the first 47 (referred to as Part 1) were randomized to fixed doses of desmoteplase (25 mg, 37.5 mg, or 50 mg) or placebo. Because of an excessive rate of symptomatic intracranial hemorrhage (sICH), lower weight-adjusted doses escalating through 62.5 microg/kg, 90 microg/kg, and 125 microg/kg were subsequently investigated in 57 patients (referred to as Part 2). The safety endpoint was the rate of sICH. Efficacy endpoints were the rate of reperfusion on MRI after 4 to 8 hours and clinical outcome as assessed by NIHSS, modified Rankin scale, and Barthel Index at 90 days. Part 1 was terminated prematurely because of high rates of sICH with desmoteplase (26.7%). In Part 2, the sICH rate was 2.2%. No sICH occurred with placebo in either part. Reperfusion rates up to 71.4% (P=0.0012) were observed with desmoteplase (125 microg/kg) compared with 19.2% with placebo. Favorable 90-day clinical outcome was found in 22.2% of placebo-treated patients and between 13.3% (62.5 microg/kg; P=0.757) and 60.0% (125 microg/kg; P=0.0090) of desmoteplase-treated patients. Early reperfusion correlated favorably with clinical outcome (P=0.0028). Favorable outcome occurred in 52.5% of patients experiencing reperfusion versus 24.6% of patients without reperfusion. Intravenous desmoteplase administered 3 to 9 hours after acute ischemic stroke in patients selected with perfusion/diffusion mismatch is associated with a higher rate of reperfusion and better clinical outcome compared with placebo. The sICH rate with desmoteplase was low, using doses up to 125 microg/kg.
                Bookmark

                Author and article information

                Journal
                ENE
                Eur Neurol
                10.1159/issn.0014-3022
                European Neurology
                S. Karger AG
                0014-3022
                1421-9913
                2008
                April 2008
                08 February 2008
                : 59
                : 5
                : 229-236
                Affiliations
                aDanish Research Center of Magnetic Resonance, Hvidovre Hospital, University of Copenhagen, bNeurobiology Research Unit and cDepartment of Neurology, Rigshospitalet, University of Copenhagen, and dDepartment of Neurology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark
                Article
                115636 Eur Neurol 2008;59:229–236
                10.1159/000115636
                18264011
                © 2008 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 1, Tables: 2, References: 30, Pages: 8
                Categories
                Original Paper

                Comments

                Comment on this article