0:01

One of the classic predicaments of residents

0:04

on the emergency department service for

0:08

neuroradiology is assessment of whether the falx

0:13

or the tentorium is showing a subdural hematoma.

0:19

And I must admit that even I, after 30 years of

0:22

doing neuroradiology practice, sometimes scratch

0:25

my head and say, is that just the dense, uh, falx?

0:30

Or is there blood on the falx?

0:32

Fortunately, as you've heard with respect to

0:36

the surgical indications for disease, unless

0:39

it gets 10 millimeters thick or 15 millimeters

0:42

thick, it's really not going to be, uh,

0:46

an issue that the patient requires surgery.

0:49

So here we have a patient.

0:52

On the right-hand side, where you see the posterior

0:55

falx and you're just seeing the leaflets of the

0:58

tentorium, and it seems dense, is there blood

1:04

on the tentorium or on this posterior falx?

1:08

Again, sometimes this is a judgment call.

1:10

You'll look at the anterior falx and see

1:12

whether it too has a similar density.

1:14

You'll look at the leaflets of the tentorium along the

1:19

transverse sinus and see whether it has

1:21

a similar density, and you make a judgment.

1:23

And sometimes that judgment's right,

1:25

and sometimes that judgment's wrong.

1:27

In this case, on the left-hand image, it's asymmetrical.

1:32

So if I see that it seems as if it's more

1:35

right-sided or left-sided or unilateral density,

1:41

I'm gonna suggest this is a subdural

1:43

hematoma along the posterior falx.

1:46

Coming to the area of the torcula and layering

1:49

onto the top of the tentorium on the right side.

1:54

Because it's asymmetrical, this one symmetrical, more

1:58

likely going to suggest that this is just a dense falx.

2:02

Now, if you're in the situation where you're

2:04

just uncomfortable with it, then recommend

2:06

a follow-up study to see whether it evolves.

2:09

But the surgeon is not going to

2:11

operate on a very small, thin,

2:15

posterior falx or tentorial subdural hematoma.

2:20

Another example, in this case,

2:23

dense falx, dense tentorium.

2:25

More on the left side than the right side.

2:30

But I look anteriorly.

2:32

This anterior falx is also dense.

2:34

Well, in this case, the patient had

2:37

a subdural along the falx that was

2:40

going from anterior to posterior.

2:42

This one again, I would call positive.

2:44

This one's pretty obviously positive.

2:47

This is actually a follow-up to the previous case.

2:50

This was the initial scan. I did call a small subdural

2:55

hematoma along the posterior falx and going to the

2:58

tentorium. We got a follow-up scan, and you can see

3:01

that it actually enlarged in size in this example.

3:06

So,

3:07

judgment it is. It is a judgment call, and if you are

3:11

uncomfortable with it or you haven't developed a

3:13

frame of reference for good judgment, it's appropriate

3:16

to ask for a follow-up study in order to clarify

3:20

whether this is a subdural hematoma that may grow,

3:23

or whether it's a tiny subdural hematoma that's

3:26

inconsequential, or whether it's just a dense falx.

3:31

Here.

3:31

Another example, tentorium on the—

3:35

left side more dense than the

3:37

tentorium on the right side.

3:39

How about this side?

3:40

Both sides are a little bit dense

3:43

for tentorial subdural hematomas.

3:46

I'd like to reconstruct the thin

3:48

sections into the coronal plane,

3:51

and then look at this tentorium on that basis.

3:54

If it remains a thin tentorium that is symmetric

3:58

in density, I do not call a subdural hematoma.

4:01

If there is any asymmetry from right to left,

4:04

or asymmetry in the density of the tentorium,

4:07

then I will call it. Sometimes you're just in

4:11

the plane of the horizontal portion of the

4:15

tentorium on an axial scan, so it looks

4:18

thicker than the contralateral side.

4:20

In this case, I'm concerned about

4:22

this as a subdural hematoma.

4:24

I'm also concerned along the anterior falx here

4:27

that there may be blood products associated here.

4:30

It looks as if—if this is not bone—like

4:33

there may be some parenchymal hemorrhage.

4:35

So now I have a potential for a coup-contrecoup injury,

4:39

and I'm more likely to call this a positive finding.

4:43

This I would pass

4:44

as just being a dense tentorium,

4:47

with no other findings on the CT scan.

4:52

Similarly, you often have patients where you

4:54

are wondering whether there are blood products

4:57

on the sinus itself, and once again, use

5:01

symmetry. If it's asymmetrical, one side to the

5:04

other, it's more likely to be a subdural collection

5:08

along the sinus or an epidural collection.

5:10

Dissecting the sinus, as you see in this case where

5:14

it's a bilateral collection, which is crossing

5:16

the midline—an epidural hematoma secondary to

5:20

a transverse sinus injury.