So here’s an example of an epidural hematoma.
So you can see that there is a large collection of blood on the right side of the brain here
and it’s hyperdense so it’s white.
It’s biconvex or lens-shaped that’s very characteristic of an epidural hematoma,
if it’s boat out on both sides that suggest that it’s an epidural.
It doesn’t cross the suture lines.
It’s very commonly associated with mass effect and on this particular CT
you can actually see the midline is bowing over to the contralateral side
and then it’s got a heterogeneous appearance
so that suggest that there’s blood of different ages in there
and in particular in the case of epidural hematoma,
that can suggest active bleeding that is ongoing right now.
So this particular hematoma is in the parietal temporal region
which is the common place that we see epidural hematomas,
the most commonly associated with injuries to the middle meningeal artery
and that’s about two-thirds of cases you’re gonna see them in this region of the brain.
So epidurals are caused by direct blows to the skull that separate the dura mater from the skull.
Shear forces associated with the blow will disrupt blood vessels which are typically arteries.
Again, the middle meningeal artery’s the most commonly affected one.
This allows blood to collect in between the skull and the dura and ultimately
it leads to compression of the brain and elevated intracranial pressure if it goes on untreated.
Now the classic presentation of an epidural hematoma
is an immediate period of loss of consciousness right after the blow to the head
followed by the patient waking up and having what’s called a lucid interval.
So they’ll wake up and they’ll be pretty much okay,
however, they will progressively deteriorate over time
and become more and more obtunded until they become comatose.
Now, epidurals are almost always associated with acute trauma
and it takes a lot of force to produce this type of bleeding in the brain.
So this is gonna be associated with high velocity, high force blows to the head
and because you’re dealing with arterial bleeding the symptoms often evolve very rapidly
so these patients will go from being like pretty good, awake and talking
to completely comatosed in a very short period of time.
The management of epidural hematoma is always gonna be emergent surgical evacuation.
These patients need to go to the operating room
and they need to have the blood drained out of their brain,
otherwise, the bleeding is gonna continue,
the mass effect is gonna get worse and the patient is ultimately gonna herniate.
Let’s move on now to subdural hematoma.
So subdurals also appear hyperdense or white when they’re acute
but they can become isodense or gray when they’re more subacute.
So subdurals accumulate more gradually overtime and in many cases if they’re chronic,
they can be hard to see because they’re basically the same density as the brain.
Unlike epidurals, subdurals are crescent-shaped so they’re not biconvex,
they’re convex on one side and concave on the other sort of like the crescent moon.
Subdurals will cross the suture lines because they’re inside of the dura
which is not tethered to the skull,
the blood can sort of interpolate all around the brain and you may see mass effect in this case.
Now the image that we’re showing here is a very, very large, very dramatic subdural hematoma.
You can see that there’s both bright white hyperdense blood as well as more gray isodense blood
so this suggest that there’s sort of acute on chronic bleeding.
There’s blood of different ages in this collection so the patient probably has had it for some time.
There is significant mass effect in midline shift
so you can see that the midline is both all the way over to the contralateral side,
there’s effacement of the ventricles.
So this is a large and very dangerous subdural hematoma.
Now the pathophysiology of subdural hematoma is a little bit different
so in the case of subdural some type of shear force disrupts bridging veins
in between the brain and the dura.
This allows blood to collect in that region between the brain and the dura
and eventually if the bleed gets large enough
you may see compression of the brain and elevated intracranial pressure,
but because we’re not dealing with arterial bleeding this accumulate much more slowly
and in many cases will not produce mass effect.
This also can be associated with relatively mild trauma.
So patients can come in with subdural hematomas with no significant history of trauma
or very minimal trivial traumas.
So you wanna have a high index of suspicion for this.
It’s also not uncommon that patients will present subacutely,
so they hit their head several days ago,
their blood has been accumulating gradually and now they’re becoming symptomatic
so they make their way to the ED.
We see subdurals much more often in elderly patients and patients who are anticoagulated.
So this is not really a disease of young people the way that epidurals are
and the symptoms tend to evolve more slowly overtime
because the blood does accumulate more gradually.
Patients like the one on our last CT image do require emergent surgical evacuation
if they’ve got large hematomas,
if they’ve got a lot of mass effect or if they have a lot of neurologic dysfunction.
However, for small bleeds it might be appropriate to simply observe the patient
if they’re neurologically intact and kinda see if the blood is continuing to accumulate,
if the bleed is expanding,
if the patient is getting worse, et cetera.