0:01

This was a child who was in a motor vehicle collision.

0:05

The CT scan

0:09

is remarkable for an extra-axial collection,

0:14

which is located in a somewhat unusual location,

0:18

what we would call the retroclival space.

0:22

Let me mark that.

0:24

Here we have the collection of acute blood

0:29

products which is behind the clivus,

0:33

extending to the petrous apex bilaterally.

0:38

This is a collection which is often very difficult to

0:43

identify on CT because of beam hardening artifact

0:48

from the bone of the posterior fossa.

0:53

So normally, we would have a lot of difficulty

0:55

with identifying it. In this case,

0:57

it's large enough that you see it extending down the

1:00

length of the clivus to the left of midline,

1:03

and then up along the petrous apex.

1:08

This is an isolated

1:10

retroclival subdural hematoma on the CT scan.

1:16

I want to demonstrate this also on an MRI scan that

1:20

the patient had subsequently the same day.

1:23

To identify retroclival subdural hematomas,

1:27

the best sequences to look at would be the sagittal scans

1:32

because it will show the bone of the clivus,

1:36

as well as the collection,

1:38

which is generally oriented in a superior-inferior

1:41

dimension quite nicely.

1:43

So this patient, as you can see,

1:46

has an extra-axial collection, behind the clivus,

1:50

as a retroclival subdural hematoma.

1:54

On the T2-weighted scan,

1:59

you can see that this would be a difficult diagnosis

2:02

to make because of the normal amount of CSF pulsation

2:07

artifact that we see in the subarachnoid

2:11

space anterior to the brain stem.

2:13

And it would be even more difficult on the FLAIR scans.

2:17

The FLAIR scans often show bright signal intensity

2:21

in this region due to CSF pulsation.

2:24

So, really have to rely most heavily

2:26

on the sagittal T1-weighted scan.

2:30

This is a post-gadolinium enhanced scan.

2:33

As you can see,

2:34

the collection is seen on that as well,

2:36

even though the patient chose motion artifact.