| The concept of the penumbra: can it be translated to stroke management? | |
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MedLine Citation:
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PMID: 20636712 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The 'penumbra' is a concept coined in animal experiments suggesting that functionally impaired tissue can survive and recover if sufficient reperfusion is re-established within a limited time period, which depends on the level of residual flow. In an ischaemic territory, irreversible damage progresses over time from the centre of the most severe flow reduction to the periphery with less disturbed perfusion. This centrifugal progression of irreversible tissue damage is characterised by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusion disturbances. Waves of depolarisations, the peri infarct spreading depressions, inducing activation of ion pumps and liberation of excitatory transmitters play an important role in the drastically increased metabolic demand during reduced oxygen supply causing hypoxic tissue changes and lactacidosis, which further damage the tissue. Positron emission tomography allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction, which can be used to identify regions with a critical reduction in these physiologic variables as indicators of penumbra and irreversible damage within ischaemic territories in animal models and patients with stroke. These positron emission tomography methods require arterial blood sampling and due to the complex logistics involved, are limited for routine application. Therefore, newer tracers were developed for the noninvasive detection of irreversible tissue damage (flumazenil) and of hypoxic tissue changes (fluoromisonidazole). As a widely applicable clinical tool, diffusion/perfusion-weighted magnetic resonance imaging is used; the 'mismatch' between perfusion and diffusion changes serves as a surrogate marker of the penumbra. However, in comparative studies of magnetic resonance imaging and positron emission tomography, diffusion-weighted imaging showed a high false-positive rate of irreversible damage, and the perfusion-weighted-diffusion-weighted mismatch overestimated the penumbra as defined by positron emission tomography. Advanced analytical procedures of magnetic resonance imaging data may improve the reliability of these surrogate markers but should be validated with quantitative procedures. |
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Authors:
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Wolf-Dieter Heiss |
Publication Detail:
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Type: Journal Article; Review |
Journal Detail:
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Title: International journal of stroke : official journal of the International Stroke Society Volume: 5 ISSN: 1747-4949 ISO Abbreviation: Int J Stroke Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-07-19 Completed Date: 2010-10-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101274068 Medline TA: Int J Stroke Country: England |
Other Details:
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Languages: eng Pagination: 290-5 Citation Subset: IM |
Affiliation:
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Max Planck Institute for Neurological Research, Cologne, Germany. wdh@nf.mpg.de |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Brain Ischemia / pathology Cerebral Infarction / diagnosis, pathology Disease Progression Energy Metabolism Humans Magnetic Resonance Imaging Positron-Emission Tomography Predictive Value of Tests Stroke / diagnosis*, metabolism, pathology, therapy* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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