Cerebral microhemorrhage
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Cerebral microhaemorrhages, or microbleeds,are usually definedsmall focal cerebral haemorrhages, often only visible on certain susceptible MRI sequences. There are frequently seen in the elderly, as <5 mm in size,hypertension and have acerebral amyloid are both common. A number of underlying causes.additional aetiologies are recognised including:
Pathology
Aetiology
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chronic hypertensive encephalopathy (common)
- typically involve the basal ganglia, thalami as well as brain stem, cerebellum and corona radiata
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cerebral amyloid angiopathy (common)
- typically involves the grey-white matter junction; usually spares the basal ganglia
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cavernous malformations
- multiple (familial) cavernous malformation syndrome
- post cerebral radiotherapy
- radiation induced vasculopathy
- if not whole-brain then microhaemorrhgaes are confined to field
- septic and fat emboli
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cerebral vasculitis (primary or secondary)
: microhaemorrhages- microhaemorrhages usually located at the corticomedullary junction
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haemorrhagicdiffuse axonal injury (DAI):- typically involves the grey–white matter junction, splenium of the corpus callosum, and dorso-lateral brainstem
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haemorrhagic micrometastases (rare)
: melanoma- melanoma or renal cell carcinoma
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CADASIL (rare)
: microhaemorrhages- microhaemorrhages have been reported to occur in 25–70%of cases without a characteristic distribution
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progressive facial hemiatrophy (PFHA)
, also named as Parry-Romberg syndrome(very rare)
Radiographic features
They are best seen on susceptibility weighted T2* sequences such as gradient echo (GRE) and susceptibility weighted imaging (SWI), and show up as very conspicuous punctate regions of signal drop out which bloomswith blooming artifact. This blooming grossly overestimates the size of the lesions, and they are usually inapparent on other sequences. ThusAs such the sometimes used definition of 5 mm or less in size is difficult as it is sequence dependent, and should certainly not be reserved for imagingapplied to sequences which does not suffer fromexhibit blooming.
Differential diagnosis
- artificial heart valve metallic emboli (very rare)
- pneumocephalus (very rare without proceeding surgery) 2
-<p><strong>Cerebral microhaemorrhages</strong>, or<strong> microbleeds</strong>,<strong> </strong>are usually defined as <5 mm in size, and have a number of underlying causes.</p><h4>Pathology</h4><h5>Aetiology</h5><ul>- +<p><strong>Cerebral microhaemorrhages</strong>, or<strong> microbleeds</strong>,<strong> </strong>are small focal cerebral haemorrhages, often only visible on certain susceptible MRI sequences. There are frequently seen in the elderly, as hypertension and cerebral amyloid are both common. A number of additional aetiologies are recognised including: </p><ul>
-<li>septic and fat emboli </li>-<a href="/articles/cerebral-vasculitis">cerebral vasculitis</a> (primary or secondary): microhaemorrhages usually located at the corticomedullary junction</li>-<li>haemorrhagic <a href="/articles/diffuse-axonal-injury-dai">diffuse axonal injury (DAI)</a>: typically involves the grey–white matter junction, splenium of the corpus callosum, and dorso-lateral brainstem </li>- +<a href="/articles/radiation-induced-vasculopathy">radiation induced vasculopathy</a><ul><li>if not whole-brain then microhaemorrhgaes are confined to field</li></ul>
- +</li>
- +<li>septic and fat emboli</li>
- +<li>
- +<a href="/articles/cerebral-vasculitis">cerebral vasculitis</a> (primary or secondary)<ul><li>microhaemorrhages usually located at the corticomedullary junction</li></ul>
- +</li>
-<a href="/articles/haemorrhagic-micrometastases">haemorrhagic micrometastases</a> (rare): melanoma or renal cell carcinoma </li>- +<a href="/articles/diffuse-axonal-injury-dai">diffuse axonal injury (DAI)</a><ul><li>
- +<a href="/articles/diffuse-axonal-injury-dai"></a>typically involves the grey–white matter junction, splenium of the corpus callosum, and dorso-lateral brainstem </li></ul>
- +</li>
-<a href="/articles/cadasil">CADASIL</a> (rare): microhaemorrhages have been reported to occur in 25–70%of cases without a characteristic distribution</li>- +<a href="/articles/haemorrhagic-micrometastases">haemorrhagic micrometastases</a> (rare)<ul><li>melanoma or renal cell carcinoma </li></ul>
- +</li>
- +<li>
- +<a href="/articles/cadasil">CADASIL</a> (rare)<ul><li>microhaemorrhages have been reported to occur in 25–70%of cases without a characteristic distribution</li></ul>
- +</li>
-<a href="/articles/progressive-facial-hemiatrophy-pfha">progressive facial hemiatrophy (PFHA)</a>, also named as Parry-Romberg syndrome (very rare)</li>-</ul><h4>Radiographic features</h4><p>They are best seen on susceptibility weighted T2* sequences such as <a href="/articles/gradient-echo-sequences-1">gradient echo</a> (GRE) and <a href="/articles/susceptibility-weighted-imaging-1">susceptibility weighted imaging</a> (SWI), and show up as very conspicuous punctate regions of signal drop out which blooms. This grossly overestimates the size of the lesions, and they are usually inapparent on other sequences. Thus the definition of 5 mm or less in size is difficult and should be reserved for imaging which does not suffer from blooming. </p><h4>Differential diagnosis</h4><ul>- +<a href="/articles/progressive-facial-hemiatrophy-pfha">progressive facial hemiatrophy (PFHA)</a> (very rare)</li>
- +</ul><h4>Radiographic features</h4><p>They are best seen on susceptibility weighted T2* sequences such as <a href="/articles/gradient-echo-sequences-1">gradient echo</a> (GRE) and <a href="/articles/susceptibility-weighted-imaging-1">susceptibility weighted imaging</a> (SWI), and show up as very conspicuous punctate regions of signal drop out with <a title="Blooming artifact" href="/articles/blooming-artifact">blooming artifact</a>. This blooming grossly overestimates the size of the lesions, and they are usually inapparent on other sequences. As such the sometimes used definition of 5 mm or less in size is difficult as it is sequence dependent, and should certainly not be applied to sequences which exhibit blooming. </p><h4>Differential diagnosis</h4><ul>
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Case 32: chronic hypertension
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