Intracranial hemorrhage CT

	Intracranial hemorrhage Microchapters
Patient Information
Overview
Classification Subdural hematoma Epidural hematoma Subarachnoid hemorrhage Intraventricular hemorrhage Intraparenchymal hemorrhage
Causes
Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

CT

CT scan (computed axial tomography) is the definitive tool for accurate diagnosis of an intracranial hemorrhage.

Cerebral amyloid angiopathy manifests radiologically as part or all of a constellation of findings including:
- Acute or chronic ICHs in a distinctive cortical-subcortical distribution
- Leukoencephalopathy
- Atrophy

CT allows rapid establishment of the presence or absence of an ICH and exclusion of an acute cerebral infarction.
Non-enhanced head CT is the preferred imaging modality for initial work-up as it provides crucial information regarding the characteristics of the ICH, including size, location, shape, and extension to the extra-axial spaces.
If an ICH is present in a cortical-subcortical location suspicious for cerebral amyloid angiopathy, the patient should undergo additional evaluation with MR imaging.
GRE is currently the most sensitive MR imaging sequence for detection of the chronic cortical-subcortical microhemorrhage.

Typical appearance is a biconvex, elliptical, extra-axial fluid collections.
Acute EDH may contain both a hyperattenuating clot and a swirling lucency (believed to represent a mixture of active bleeding and the serum remaining after previous clot formation).
Subacute EDH becomes homogeneously hyperattenuating.
Chronic EDH is at least partly hypoattenuating as the clot undergoes breakdown and resorption.

Subarachnoid hemorrhage appears as a high-attenuating, amorphous substance that fills the normally dark CSF-filled subarachnoid spaces.
These findings are most evident in the largest subarachnoid spaces, such as the suprasellar cistern and Sylvian fissures.
Acute subarachnoid hemorrhage is typically 50-60 HU.
When CT scanning is performed several days to weeks after the initial bleed, the findings are more subtle.
- The initial high-attenuation of blood and clot tend to decrease, and these appear as intermediate gray.
- These findings can be isointense relative to normal brain parenchyma.
In addition to detecting subarachnoid hemorrhage, CT is useful in localizing the source of bleeding.

Unlike epidural hematomas, subdural hematomas are not restricted by dural tethering at the cranial sutures.
- They can cross suture lines and continue along the falx and tentorium.
- They do not cross the midline because of the meningeal reflections.

In the acute phase, subdural hematomas appear as a crescent-shaped extra-axial collection with increased attenuation that, when large enough, causes effacement of the adjacent sulci and midline shift.
The attenuation changes as the hematoma ages.