The next form of intracranial bleed is a subdural hematoma. This is due to tearing of
bridging veins as a result of trauma. We do see in the illustration an example of a bridging
vein. It is shown right in through here. It’s running within the subarachnoid space
and then will cross the arachnoid mater and then drain into, in this case the superior
sagittal sinus. So, if there’s any rupture or tearing of this bridging vein along its course
that will cause a bleed that is going to be subdural in its variety. That will separate
the dura mater from the arachnoid mater as a result. So what are the structural
and clinical considerations of a subdural hematoma? Again, the first consideration is
it’s due to a tearing of a bridging vein or maybe multiple bridging veins due to head trauma.
As a result, the hemorrhage will separate the meningeal layer specifically of the dura mater
and the arachnoid. So the bleed then causes this pathologic subdural space of which we see
over here on the left side of the image. We also see another subdural bleed over here
on the right side of the image. This is bleeding into the lateral sulcus region. Again,
a subdural hematoma will create a pathologic space, the subdural space, as it separates
the meningeal layer of the dura mater from the arachnoid mater. Its appearance is different
from that of an epidural hematoma. The subdural hematoma is said to be crescent-shaped
in its appearance. We can appreciate it on this side of the image. The increased intracranial
pressure may cause herniation of the cingulate gyrus or of the uncus. But being a tear of a
vein, these are much slower bleeds. These tend to be more common in the elderly
and in individuals who are chronic alcoholics. As we age, our brain just shrinks or undergoes
atrophy. In chronic alcoholics, they will accelerate the course of brain atrophy. This just
increases the space then between the brain and the dura where the bridging veins are found.
With trauma to the skull, there’s much more tension or forces being placed on these bridging
veins due to a smaller brain. Here, we’re looking at a subdural bleed into the lateral
fissure as mentioned before. We can see here along the outer cortical area, we can see
that this increased pressure of the subdural hematoma is starting to produce edema.
This edema then is tissue swelling. Here, we’re looking at a post-mortem view of a subdural
hematoma. In this case, the subdural hematoma occurred bilaterally. You can
appreciate the large hematoma regions here, black arrows on this side and then
one black arrow on this side. This dark substance represents the hematoma.
This structure here that is separating both bleeds is the falx cerebri.