Alright, so now we’re gonna move on to traumatic subarachnoid.
So in the case of subarachnoid hemorrhage,
you’ll see hyperdensity or blood, either in the sulci of the brain or in the basilar cisterns
and you can see this in either a localized or diffuse way.
So you can see there is a bright way area in the CT image that’s labeled localized
that’s a relatively small self-contained area of subarachnoid blood,
whereas in the diffuse one you can see that the blood is on both sides of the brain
that it sort of percolated through the sulci in the entire frontal region of the brain
so it’s much more extensive than the localized one on the other side.
You can get blood in the cerebral aqueduct or in the 3rd ventricle
and if you get blood in that region and it clots it can actually obstruct CSF flow
and cause hydrocephalus so this can be quite dangerous
when they involve the ventricular system
because they can lead very rapidly to elevated intracranial pressure from hydrocephalus.
So pathophysiologically, subarachnoid bleeds occur
when there’s blood between the pia mater and the arachnoid mater.
There are few different mechanisms for this
so if you get a cerebral contusion with small vessel bleeding,
the blood can sort of diffuse into that subarachnoid space
or you can get vascular injury from shear forces as well
leading to bleeding into the subarachnoid space.
You can see subarachnoid blood with either mild or severe trauma.
This is a very common finding in young patients who have acute injuries
and the volume of blood in the subarachnoid space correlates very strongly
with their initial GCS and with the prognosis.
Now, subarachnoid bleeds can be medical as well so you always wanna consider the possibility
that the patient has had an aneurysmal cause of hemorrhage
rather than a traumatic cause of hemorrhage.
So generally, these patients should get some type of vascular imaging
to rule out the possibility of an aneurysm.
Generally, the treatment for subarachnoid hemorrhage in the trauma setting
is just gonna be supportive care and observation in an intensive care unit setting.
But these patients will often have delayed vasospasm days after their initial trauma
and in some cases might need to be treated with calcium channel blockers,
specifically nimodipine for that,
however, that’s not really an issue that we address in the Emergency Department.
Alright, moving on to intraparenchymal hemorrhage.
So here you see a very well demarcated bright white hyperdense lesions
that are actually inside of the brain tissue.
So there are collections of blood that are focal that are surrounded on all sides by brain parenchyma.
This can be seen immediately in the post-trauma setting
but they more commonly evolve over hours to days.
So in some cases you know the patient might come in and have a negative initial head CT
or a very small area of contusion on their head CT
that actually goes on to develop into a much larger intraparenchymal hemorrhage.
Mass effect is quite common with this.
This can be neurologically devastating and you can see in this particular case
you’ve got the two bright white hematomas that are marked on the slide
and you’ve got evidence of mass effect, so you’ve got effacement of the ventricle,
you’ve got midline shift and if you note up on the top of the image
there’s actually a ventriculostomy catheter in place
so this patient is having continuous intracranial pressure monitoring via the ventriculostomy catheter
and they can have CSF drained out if necessary to reduce the intracranial pressure if it’s rising .
So pathophysiologically, these hematomas happen anytime, blood clots within the brain tissue
and it’s typically gonna be associated with vascular injury from direct trauma.
Again, these are usually associated with severe acute trauma.
It takes a lot of force to do this to the brain,
however, because you’re dealing with relatively small vessel bleeds
the findings on CT scan and the neurologic findings might evolve slowly over hours to days.
Anytime you have an intraparenchymal hematoma
your care is gonna be largely supportive so the most important thing you can do
is stop them from bleeding further so you wanna reverse any anticoagulation,
you wanna control their blood pressure
and you wanna make sure that you control their intracranial pressure as well
which we’re gonna talk about in more detail shortly.