An intracerebral hemorrhage, or intraparenchymal cerebral hemorrhage, is a subset of an intracranial hemorrhage and encompasses a number of entities that have in common the acute accumulation of blood within the parenchyma of the brain. The etiology, epidemiology, treatment and prognosis vary widely depending on the type of hemorrhage, and as such, these are discussed separately.
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Pathology
They are most often broadly divided according to whether they are spontaneous (primary) or due to an underlying lesion (secondary), and then further divided according to etiology and/or location.
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primary hemorrhages (no underlying lesion)
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secondary hemorrhages (some other lesion complicated by hemorrhage)
vascular malformation
tumor (primary or secondary)
Radiographic features
CT
CT is usually the modality first obtained and demonstrates a hyperdense collection of blood, often with surrounding hypodense edema. A number of complications may be present, such as extension of the hemorrhage into other intracranial compartments, hydrocephalus, herniation, etc.
The hemorrhage may be present anywhere, examples including:
A number of CT features can predict the likelihood of hemorrhage expansion and are therefore useful in decision-making and prognosis.
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non-contrast CT
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hemorrhage size
the volume of an intracerebral hemorrhage can be measured using ABC/2 formula or 3D volumetric software
hemorrhage size is considered to be the most reliable independent predictor of ICH expansion
hematoma expansion is measured as an increased growth >12.5 mL or volume >33% from the initial CT scan
hematomas with a volume of more than 30 mL are more prone to expansion
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hemorrhage shape
intracerebral hemorrhage irregularity is thought to be due to multiple leaking vessels feeding the hematoma
hemorrhages with irregular shapes are more prone to expansion
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hemorrhage density
the presence of hypodense or isodense regions within the hyperdense intracerebral hemorrhage represents active bleeding and is called swirl sign
when the swirl sign is encapsulated it is termed black hole sign
the presence of a relatively hypodense area adjacent to a hyperdense area is termed the blend sign
heterogeneous hemorrhage with hypodense foci is more prone to expansion
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intraventricular hemorrhagic extension
intraventricular hemorrhagic extension occurs due to decompression of the hemorrhage into the low resistance ventricular system, thus; hematomas located in the thalamus, caudate nucleus or pons are more prone to intraventricular extension than lobar hematomas
a study has shown that lenticular and lobar hematomas with accompanying intraventricular extension displayed a higher proportion of hematoma expansion 5
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contrast-enhanced CT
active contrast extravasation within hematoma predicts future hemorrhage expansion, this can be observed on CT angiography (CTA) as spot sign and pooling of contrast within the hematoma
MRI
Findings depend on the size and age of the bleed (see aging blood on MRI).
Practical points
With any intracerebral hemorrhage the following points should be included in a report as they have prognostic implications 3:
location
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size/volume
the ABC/2 formula is widely used, but there may be more accurate formulas (e.g. 2.5ABC/6, SH/2) and analyzes available, some of which, however, may require the addition of specific software to the standard PACS tools
shape (irregular vs regular)
density (homogeneous vs heterogeneous)
presence/absence of substantial surrounding edema that may indicate an underlying tumor
presence/absence of intraventricular hemorrhage
presence/absence of hydrocephalus
when CT angiography is performed, the presence/absence of the CTA spot sign or a vascular malformation
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