Watershed cerebral infarction
Updates to Article Attributes
Watershed cerebral infarctions, also known as border zone infarcts, occur at the border between cerebral vascular territories where the tissue is furthest from arterial supply and thus most vulnerable to reductions in perfusion.
Epidemiology
Watershed cerebral infarction account for 5-10% of all cerebral infarctions 8. They tend to be seenoccur in the elderly, who have a higher incidence of arterial stenosis and hypotensive episodes, as well as microemboli.
Pathology
It has been proposed that both, episodes of hypoperfusion and microembolismsmicroemboli from inflamed atherosclerotic plaques, play play a role in pathophysiology of this entity, although the laterlatter is less well established 5.
Episodes of systemic hypotension, particularly with severe stenosis or occlusion of the feeding arteries, in particular intrathe intracranial and extracranial carotid arteries, is the typical scenario in which a watershed infarction is encountered.
Clearance of the microemboli, which may form on the surface of inflamed plaques, or are the result of an embolic shower, are most likely to be impaired in watershed zones due to poorer perfusion.
WatershedA watershed zone infarct in an isolated area is more likely to be secondary to microembolism, particularly in the absence of significant systemic hypotension and/or arterial stenosis. In a severe carotid stenosis, lesions are usually ipsilateral to the stenosis. Prolonged hypotension, such as during cardiac surgery or cardiac arrest, commonly gives a bilateral pattern in the absence of severe stenosis 5.
Watershed infarction has been classified toas:
-
cortical (external) border zones infarct
- between ACA, MCA, and PCA territories
- histologically, these can be wedges of cortical and subcortical infarction
,or cortical laminar necrosis
-
deep (internal) border zones infarct:
- between ACA, MCA, and PCA territories
,and perforating medullary, lenticulostriate, recurrent artery of Heubner and anterior choroidal arteries
- between ACA, MCA, and PCA territories
Radiographic features
CT and MRI
The exact pattern depends on the bordering territories, which isare usually variable in different individuals. Imaging of watershed infarction should also aim to determine the presence and severity of arterial stenosis orand occlusion.
Cortical (external) border zones infarct
These are usually wedge-shaped or gyriform:
- ACA/MCA: in the frontal cortex, extending from the anterior horn to the cortex
- MCA/PCA: in the parieto-occipital region, extending from the posterior horn to the cortex
- parallel parafalcine stripes in the subcortical white matter at the vertex- this type is seen
when there waswith profound diffuse hypoperfusion
Triple watershed zone: most vulnerable region where ACA, MCA, and PCA converge posterior to lateral ventricles inin the parieto-occipital region posterior to the lateral ventricles.
Deep (internal) border zones infarct
- ≥3 lesions, each ≥3 mm in diameter, in a linear fashion parallel to the lateral ventricles in the centrum semiovale or corona radiata, which sometimes become more confluent and band-like 7
-<p><strong>Watershed cerebral infarctions</strong>, also known as <strong>border zone infarcts</strong>, occur at the border between <a href="/articles/cerebral-vascular-territories">cerebral vascular territories</a> where the tissue is furthest from arterial supply and thus most vulnerable to reductions in perfusion. </p><h4>Epidemiology</h4><p>Watershed cerebral infarction account for 5-10% of all <a href="/articles/ischaemic-stroke">cerebral infarctions</a> <sup>8</sup>. They tend to be seen in the elderly, who have a higher incidence of arterial stenosis and hypotensive episodes, as well as microemboli. </p><h4>Pathology</h4><p>It has been proposed that both, episodes of hypoperfusion and microembolisms from inflamed atherosclerotic plaques, play a role in pathophysiology of this entity, although the later is less well established <sup>5</sup>.</p><p>Episodes of systemic hypotension particularly with severe stenosis or occlusion of the feeding arteries, in particular intra and extracranial carotid arteries, is the typical scenario in which watershed infarction is encountered. </p><p>Clearance of the microemboli, which may form on the surface of inflamed plaques, or are the result of an embolic shower, are most likely to be impaired in watershed zones due to poorer perfusion. </p><p>Watershed zone infarct in an isolated area is more likely to be secondary to microembolism, particularly in the absence of significant systemic hypotension and/or arterial stenosis. In a severe <a href="/articles/carotid-stenosis">carotid stenosis</a>, lesions are usually ipsilateral to the stenosis. Prolonged hypotension such as cardiac surgery or cardiac arrest commonly gives a bilateral pattern in the absence of severe stenosis <sup>5</sup>. </p><p>Watershed infarction has been classified to:</p><ul>- +<p><strong>Watershed cerebral infarctions</strong>, also known as <strong>border zone infarcts</strong>, occur at the border between <a href="/articles/cerebral-vascular-territories">cerebral vascular territories</a> where the tissue is furthest from arterial supply and thus most vulnerable to reductions in perfusion. </p><h4>Epidemiology</h4><p>Watershed cerebral infarction account for 5-10% of all <a href="/articles/ischaemic-stroke">cerebral infarctions</a> <sup>8</sup>. They tend to occur in the elderly, who have a higher incidence of arterial stenosis and hypotensive episodes, as well as microemboli. </p><h4>Pathology</h4><p>It has been proposed that both episodes of hypoperfusion and microemboli from inflamed atherosclerotic plaques play a role in pathophysiology of this entity, although the latter is less well established <sup>5</sup>.</p><p>Episodes of systemic hypotension, particularly with severe stenosis or occlusion of the feeding arteries, in particular the intracranial and extracranial carotid arteries, is the typical scenario in which a watershed infarction is encountered.</p><p>Clearance of the microemboli, which may form on the surface of inflamed plaques or are the result of an embolic shower, are most likely to be impaired in watershed zones due to poorer perfusion. </p><p>A watershed zone infarct in an isolated area is more likely to be secondary to microembolism, particularly in the absence of significant systemic hypotension and/or arterial stenosis. In a severe <a href="/articles/carotid-stenosis">carotid stenosis</a>, lesions are usually ipsilateral to the stenosis. Prolonged hypotension, such as during cardiac surgery or cardiac arrest, commonly gives a bilateral pattern in the absence of severe stenosis <sup>5</sup>. </p><p>Watershed infarction has been classified as:</p><ul>
-<li>histologically these can be wedges of cortical and subcortical infarction, or <a href="/articles/cortical-laminar-necrosis">cortical laminar necrosis</a>- +<li>histologically, these can be wedges of cortical and subcortical infarction or <a href="/articles/cortical-laminar-necrosis">cortical laminar necrosis</a>
-<strong>deep (internal)</strong> border zones infarct: <ul><li>between ACA, MCA, and PCA territories, and perforating medullary, lenticulostriate, <a href="/articles/recurrent-artery-of-heubner-1">recurrent artery of Heubner</a> and anterior choroidal arteries</li></ul>- +<strong>deep (internal)</strong> border zones infarct: <ul><li>between ACA, MCA, and PCA territories and perforating medullary, <a title="Lenticulostriate arteries" href="/articles/lenticulostriate-arteries">lenticulostriate</a>, <a href="/articles/recurrent-artery-of-heubner-1">recurrent artery of Heubner</a> and <a title="Anterior choroidal artery" href="/articles/anterior-choroidal-artery">anterior choroidal arteries</a>
- +</li></ul>
-</ul><h4>Radiographic features</h4><h5>CT and MRI</h5><p>The exact pattern depends on the bordering territories which is usually variable in different individuals. Imaging of watershed infarction should also aim to determine presence and severity of arterial stenosis or occlusion.</p><h6>Cortical (external) border zones infarct</h6><p>These are usually wedge-shaped or gyriform:</p><ul>-<li>ACA/MCA: in frontal cortex extending from anterior horn to the cortex</li>-<li>MCA/PCA: in parieto-occipital region extending from posterior horn to the cortex</li>-<li>parallel parafalcine stripes in subcortical white matter at the vertex- this type is seen when there was profound diffuse hypoperfusion</li>-</ul><p>Triple watershed zone: most vulnerable region where ACA, MCA, and PCA converge posterior to lateral ventricles in parieto-occipital region.</p><h6>Deep (internal) border zones infarct</h6><ul><li>≥3 lesions, each ≥3 mm in diameter in a linear fashion parallel to the lateral ventricles in the <a href="/articles/centrum-semiovale-1">centrum semiovale</a> or <a href="/articles/corona-radiata">corona radiata</a>, which sometimes become more confluent and band-like <sup>7</sup>- +</ul><h4>Radiographic features</h4><h5>CT and MRI</h5><p>The exact pattern depends on the bordering territories, which are usually variable in different individuals. Imaging of watershed infarction should also aim to determine the presence and severity of arterial stenosis and occlusion.</p><h6>Cortical (external) border zones infarct</h6><p>These are usually wedge-shaped or gyriform:</p><ul>
- +<li>ACA/MCA: in the frontal cortex, extending from the anterior horn to the cortex</li>
- +<li>MCA/PCA: in the parieto-occipital region, extending from the posterior horn to the cortex</li>
- +<li>parallel parafalcine stripes in the subcortical white matter at the vertex - this type is seen with profound diffuse hypoperfusion</li>
- +</ul><p>Triple watershed zone: most vulnerable region where ACA, MCA, and PCA converge in the parieto-occipital region posterior to the lateral ventricles.</p><h6>Deep (internal) border zones infarct</h6><ul><li>≥3 lesions, each ≥3 mm in diameter, in a linear fashion parallel to the lateral ventricles in the <a href="/articles/centrum-semiovale-1">centrum semiovale</a> or <a href="/articles/corona-radiata">corona radiata</a>, which sometimes become more confluent and band-like <sup>7</sup>
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