Ischemic penumbra

The concept of the ischemic penumbra is an important one for both basic investigators of cerebral ischemia and for clinicians who treat stroke patients. The ischemic penumbra has been defined in a variety of ways, but the most clinically relevant definition is that portion of the ischemic territory that is still potentially salvageable, if an appropriate treatment is given. Currently, three main challenges persist for those interested in the ischemic penumbra concept: how can this ischemic region be most accurately identified in stroke patients, what mechanisms of ischemic cell death are most important for progression from penumbra towards irreversible injury and what therapeutic modalities are most likely to impede the development of infarction? Much important information regarding each of these topics has become available recently and will be the focus of this paper. 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 regulatio...

Kara Jo Swafford, MD Stroke. 2018 The ischemic penumbra represents hypo-perfused tissue at risk of infarction if cerebral blood flow is not restored and may persist for hours after onset of ischemia. Progression from penumbra to infarction may be delayed due to the presence of collateral circulation. The 2018 American Heart Association acute ischemic stroke guidelines, in part based on the results of the DAWN and DEFUSE 3 trials, support the use of perfusion imaging for identifying patients with potentially salvageable tissue to help in selecting appropriate candidates for mechanical thrombectomy. Limited data exists on penumbra characteristics in patients with untreated acute ischemic stroke compared to those receiving reperfusion therapy within a delayed time window (i.e., up to 24 hours after stroke onset). Vagal et al designed a multicenter retrospective cross-sectional study to investigate how time from stroke onset may affect penumbral salvage and infarct growth in untreated acute ischemic stroke patients within the first 24 hours, including the role of collaterals. Analyzing data from 94 patients, their study suggests collateral cerebral blood flow is important in the natural evolution of ischemic injury, regardless of the timing of penumbra assessment. Greater collateral circulation was associated with greater penumbral salvage and less infarct growth within the first 24 hours. Time of stroke onset was not associated with either penumbral salvage or infarct growth....

Lucie Chalet 1,2, Timothé Boutelier 2, Thomas Christen 3, Dorian Raguenes 2, Justine Debatisse 1, Omer Faruk Eker 4,5, Guillaume Becker 1, Norbert Nighoghossian 1,6, Tae-Hee Cho 1,6, Emmanuelle Canet-Soulas 1 and Laura Mechtouff 1,6 * • 1Univ Lyon, CarMeN Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Lyon, France • 2Olea Medical, La Ciotat, France • 3Grenoble Institut Neurosciences, INSERM, U1216, Univ. Grenoble Alpes, Grenoble, France • 4CREATIS, CNRS UMR-5220, INSERM U1206, Université Lyon 1, Villeurbanne, France • 5Neuroradiology Department, Hospices Civils of Lyon, Lyon, France • 6Stroke Department, Hospices Civils of Lyon, Lyon, France The ischemic penumbra is defined as the severely hypoperfused, functionally impaired, at-risk but not yet infarcted tissue that will be progressively recruited into the infarct core. Early reperfusion aims to save the ischemic penumbra by preventing infarct core expansion and is the mainstay of acute ischemic stroke therapy. Intravenous thrombolysis and mechanical thrombectomy for selected patients with large vessel occlusion has been shown to improve functional outcome. Given the varying speed of infarct core progression among individuals, a therapeutic window tailored to each patient has recently been proposed. Recent studies have demonstrated that reperfusion therapies are beneficial in patients with a persistent ischemic penumbra, beyond conventional time windows. As a result, mapping the penumbra has become...

Farlex Partner Medical Dictionary © Farlex 2012 ischemic penumbra Neurology An ischemic zone in the brain at risk of infarction, which lies in a 'no-man's land' between a zone of low blood flow–< 25 ml/100 mg brain tissue/min and a zone where brain tissue is undergoing necrosis–flow–< 8 ml/100 mg/min. Cf rt-PA is a serine protease which can specifically bind fibrin to lyse the provaline-arginine junction, thus activating plasminogen, forming fibrinolytic enzyme, dissolving blood clots, promoting blood flow recovery in ischemic penumbra, saving nerve cells and promoting the recovery of nerve function in patients.15 In recent years, mild hypothermia has been recognized as an important method of neuroprotection. [3] Studies suggest the likelihood of its neuroprotective action by reducing the levels of circulating and brain catecholamines and thus balancing the ratio between cerebral oxygen supplies, reducing excitotoxicity, and improving the perfusion in the ischemic penumbra. It reduces the levels of the glutamate responsible for cellular brain injury, especially in subarachnoid haemorrhage. In physiological conditions, the diameter of the blood vessel is the main regulator of cerebral blood flow, while in blood vessel occlusion most of the penumbra perfusion originates from collaterals, which enables retrograde perfusion of the penetrating arterioles of the ischemic penumbra after AIS [28]. Hyperglycemia disturbs collateral circulation of ischemic penumbra, increases the re...

The brain depends on a constant supply of blood for the oxygen and nutrients it needs to survive. Pipe-like vessels called arteries carry oxygenated blood from the heart and lungs to all parts of the brain. AIS can occur when blood flow through one of these arteries is blocked. Stroke robs the brain of oxygen, causing brain cells to become damaged or die. As a result, parts of the body controlled by those cells often become disabled. Ischemic stroke represents 87% of all strokes. A large vessel occlusion is a severe and debilitating type of ischemic stroke as the clot occludes major arteries and prevents blood flow to significant portions of the brain. IMPORTANT NOTE: This overview is provided for informational purposes only and should not be used as a substitute for talking with your doctor. Be sure to talk with your doctor for a complete discussion of this condition as well as the benefits and risks of any treatment options. Symptoms All stroke types can cause serious, sometimes fatal, complications. Stroke symptoms can vary from person to person depending on stroke type and location in the brain. The acronym BE FAST (Balance, Eyes, Face, Arm, Speech, Time) has been popularized in the United States and elsewhere to teach the telltale signs of stroke and the critical need to contact emergency services immediately. Difficulties with balance, blurred vision, face drooping, arm weakness, and speech difficulty are the outward signs that it’s time to call 911. Symptoms may inc...