0:01

Let's take a look at this case and analyze it

0:04

because the patient presented with vocal

0:06

cord paresis on the left side.

0:09

Here we have a mass that is situated

0:12

at the skull base.

0:14

And we notice that the lesion appears to grow into

0:17

the jugular foramen.

0:19

So at first blush,

0:21

we might say, well, you know,

0:22

is this a glomus jugulare tumor?

0:25

It's growing from the skull base down into

0:28

the carotid sheath.

0:30

From that standpoint, it meets the criteria.

0:34

On the post-gadolinium-enhanced scan,

0:36

it is an enhancing lesion.

0:39

You can see it coursing into the jugular foramen

0:43

and even down here at the edge

0:47

of the hypoglossal canal.

0:48

This is the hypoglossal canal seen here,

0:51

and that also can occur with glomus jugulare tumors.

0:57

However, what we should be focusing on

1:00

is the presence of the jugular vein,

1:03

posterior lateral to this mass.

1:06

This jugular vein is compressed,

1:09

but the tumor is not growing into the jugular vein.

1:12

Here's the jugular vein there.

1:14

In point of fact,

1:16

it is anterior medial to the jugular vein.

1:19

Here again,

1:21

we see the flow void of the jugular vein here.

1:25

Next thing to ask is where is the carotid artery?

1:29

Here we have our carotid artery bifurcation,

1:33

and we see that the internal carotid artery is coursing

1:38

along the anterior medial border of this mass.

1:43

That would argue that this is

1:46

not a carotid body tumor,

1:49

which should have the internal carotid artery

1:51

along the posterior edge of the tumor,

1:54

separating from the external carotid artery.

1:58

This kind of intermediate signal intensity tissue

2:03

is pretty typical of Antoni A,

2:07

dominant schwannoma tissue.

2:09

The brighter signal intensity,

2:11

more likely the antony B.

2:13

So this, by virtue of the anterior medial displacement of

2:17

the internal carotid artery and the posterior

2:19

lateral displacement of the jugular vein,

2:23

argues that this is a vagus schwannoma.

2:27

But what about the involvement

2:28

of the jugular foramen?

2:30

The vagus nerve comes through the pars

2:33

vascularis of the jugular foramen.

2:37

The 9th cranial nerve comes through the

2:39

pars nervosa of the jugular foramen.

2:42

But the jugular foramen involvement does

2:44

not exclude a vagus schwannoma.

2:48

Let's make sure that we can see these vascular

2:51

displacements on our sagittal scan.

2:54

Here we have the sagittal scan,

2:56

again, showing the internal carotid artery,

3:00

as we saw in a previous case,

3:02

being displaced anteriorly by the tumor.

3:05

Identifying this as more likely a vagus schwannoma.

3:10

The jugular vein is seen over here.

3:14

It's being compressed.

3:16

I can't really identify it very well.

3:18

Let's see whether it's better on the sagittal

3:21

T2-weighted scan for the jugular vein.

3:25

Not well identified.

3:28

How about over here?

3:30

A little bit of the jugular vein over here,

3:32

but not as well seen.

3:35

Here's the jugular. Jugular. Can't see it.

3:39

In any case,

3:41

the preponderance of evidence here is that this

3:44

represents a vagus schwannoma that is growing

3:47

into the jugular foramen.