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Can anyone highlight the differences in a subarachnoid vs subdural vs epidural hemorage on a ct without contrast?
Diff in CT of sub vs epidural hemorage
- Thread starter Amicus
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Amicus said:
subdural has a very distinct crescent shape. here's a good set of images:
http://www.amershamhealth.com/medcyclopaedia/medical/volume vi 1/haematoma subdural.asp
epidural is a convex mass on ct. i've seen multiple subdurals before but only 1 epidural so there may be more nuances in an epidural, but here's a summary of the pathology w/ a ct image.
http://www.amershamhealth.com/medcyclopaedia/medical/volume vi 1/haematoma subdural.asp
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Epidural will have the biconvex shape(lentiform), usually in the temporoparietal regions but can be in the occipital region. Usually accompanied with a skull fracture and tear of a branch of the middle meningeal artery. Does NOT cross suture lines, but can cross midline. Usually has more mass effect, but not always, depending on size.
Subdural is crescent shaped typically along the temporoparietal regions as well, and is associated with tearing of the bridging veins. They DO cross sutures lines, but DO NOT cross midline. Fracture less commonly associated. Can be bilateral and also interhemispheric, and along the tentorium.
Subarachnoid you look for blood in the fissures, the basilar cisterns, interhemispheric, or in the interpeduncular fossa. If you see blood in/around the circle of willis you may get the star of texaco sign, or if you see blood along the posterior falx around the sinuses, you can get the delta sign.
Keep in mind that blood attenuates differently depending on the age, with an evolvement in attenuation from hyperdense, to isodense, to hypodense as you transition from acute, to subacute, to chronic. Mixed attenuation can occur, i.e. from a acute rebleed in a chronic subdural.
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Subdural is crescent shaped typically along the temporoparietal regions as well, and is associated with tearing of the bridging veins. They DO cross sutures lines, but DO NOT cross midline. Fracture less commonly associated. Can be bilateral and also interhemispheric, and along the tentorium.
Subarachnoid you look for blood in the fissures, the basilar cisterns, interhemispheric, or in the interpeduncular fossa. If you see blood in/around the circle of willis you may get the star of texaco sign, or if you see blood along the posterior falx around the sinuses, you can get the delta sign.
Keep in mind that blood attenuates differently depending on the age, with an evolvement in attenuation from hyperdense, to isodense, to hypodense as you transition from acute, to subacute, to chronic. Mixed attenuation can occur, i.e. from a acute rebleed in a chronic subdural.
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