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I./3.1.: Introduction: intracerebral hemorrhages in radiological point of view
I./3.1.1.: Parenchymal mass bleedings
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Large part of strokes with parenchymal damage are ischemic at the time of their development, while appr. 15% of them are hemorrhagic. Parenchymal mass hemorrhage develops usually in individuals with hypertension, and in case of hypertensive crisis. Proceeding from the area of the basal ganglia (putamen-claustrum apoplexia), extensive, desructive hemorrhage may develop which can break into the ventricules and the subarachnoideal space. Usually the patients are somewhat younger as patients with ischemic infarctions (50-60 years of age), in addition, daytime occurence is more frequent as in case of ischemic infarction.
Hypertensive mass hemorrhage is always accompanied by supratentorial cerebral edema, whose extent correlates with the actual blood pressure rise. Furthermore, small petechial bleedings can develop adjacent to them due to ischemic damage of the vessel endothelium. Hemorrhage associated with preeclampsia clearly shows the role of blood pressure rise and the disturbance of autoregulation in the development of bleeding. In this case, computed tomography (CT) images show that the border of grey and white matter will be blurred, usually occipitally. Possibly, hemorrhage may even not develop if the root cause (e.g. hipertensive crisis, cytotoxic effect) ceases and the process reverses (PRESS-syndrome). Such lesion can be established by additional causative factors, such as immunsuppressive treatment, chemotherapeutics, metronidazol, etc.
I./3.1.2.: Lobar hemorrhages
The so-called lobar hemorrhages are caused by tumor bleeding, vascular malformations , „hemorrhagic transformation” of ischemic infarction (see below), and mainly in elderly subjects amyloid angiopathy, based on hypertension or even without. Hemorrhages based on amyloid angiopathy show a characteristic sequential (cascade-like) course: sequential, possibly coherent hemorrhagic events, whose different age is also detectable based on their density.
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CT is an excellent imaging modality to detect the acute intracerebral hemorrhage. The acutely effused bleeding is hyperdense due its hemoglobin content. Since hemoglobin content is dependent on hematocrit, in exceptional cases in case of extensive anemia the acute bleeding can be isodense with the brain tissue – its detection by CT is difficult. MR imaging is able to detect the acute, subacute and chronic hematomas according to the appearence of certain phases of hemoglobin degradation on T1, T2 and T2* sequences .
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