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This was a patient with clinical findings suggestive of left trigeminal

0:05

schwannoma with brainstem compression.

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Resh kind of threw a curve ball at you because this ends up not

0:14

being a schwannoma. Um, and we'll try to explain why.

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So we're gonna look at this case again with our, our CYS imaging and, um,

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we'll do the same as what we did before. And that is to identify the,

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you know, the nerves down low,

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and that's such a great demonstration of the hypo hypoglossal nerve going

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into the hypoglossal canal there. Um,

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the nine 10 complex going towards the jugular

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foramen on either side. Um,

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here we come to the internal auditory canal,

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and on the normal right side,

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we can see multiple nerves entering the internal auditory canal.

1:02

On the affected side, the left side,

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we see that the mass demonstrated here as this kind of iso

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intense tissue is displacing

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the seventh, eighth nerve complex posteriorly.

1:18

And the mass does just enter the porous acoustics here

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on the, uh, left side.

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As we move further superiorly,

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we see the trigeminal nerve on the right side coming into Mecca's cave.

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On the left side, we honestly don't see the,

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the fifth cranial nerve. Here's Meles Cave.

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It's markedly enlarged compared to the normal Meles cave.

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And so it's filled with the mass.

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Here you can see the dural reflection being displaced

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laterally by the soft tissue in Mekel Cave.

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As we proceed more superiorly,

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we see that this lesion is on both sides of the

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tentorium. There's a component that's in the middle cranial fossa,

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and we, we see that, that it,

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it extends up further superiorly here.

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And what we're looking for

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is the third cranial nerve. And here we,

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we know that the third cranial nerve comes off between the

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posterior cerebral artery and the superior cerebellar artery.

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And so on the right side we see third cranial nerve coming from

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the intraocular cistern across and into

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cavernous sinus. On the affected side, we

2:58

Have have the third cranial nerve here from the intraocular cistern coming

3:03

across. And here's where the third cranial nerve abuts

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the mass as it enters the cavernous sinus.

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So there's contact with the third cranial nerve right here,

3:18

right?

3:20

So intraocular cistern coming across tumor against the third cranial nerve

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and then into the camera of sinus.

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So quite often the issue is not so much the histology of

3:32

the mass as it is the, um,

3:37

the important anatomy that you should be describing. We,

3:41

we talk about the nerves, the arteries, and the bones. So in this case,

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you know, we've got portions of the, um,

3:50

the vasculature here. We have the vass or artery, and

3:56

we wanna talk about whether we see any vessels that are in close

4:00

approximation to the, to the mass.

4:04

You can see superior cerebellar artery being displaced immediately by the mass.

4:09

So let's look at the post gadolinium enhanced images. Alright,

4:14

so here's our mass. And, um, how,

4:17

why would we say that this lesion is a meningioma,

4:21

which was the correct histologic diagnosis as opposed to a,

4:26

uh, fifth cornal nerve schwannoma? Well,

4:28

the shape of this lesion is more in keeping with a meningioma in that it's along

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the plane of the dura rather than along the plane of the, um,

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fifth cranial nerve, which would be more AP oriented,

4:43

if you will. We do have a little bit of a dural tail. It's not dramatic.

4:49

Um, the, the,

4:50

the lesion crossing the tentorium is another argument.

4:57

Uh, fifth cran nerve schwannomas would not be up this high at the level of the

5:01

midbrain.

5:02

And this growth in into the middle cranial fossa, uh,

5:07

argues against it being a schwannoma. Um, it is,

5:11

as you saw on the stir, relatively iso intense.

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Here's our traditional T two A image,

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and then that's true with some schwans. They may also be, uh, iso intense.

5:30

What we'd also look at would be to look for any bony reaction.

5:35

So along the petrus bone,

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we would look for any type of reaction.

5:41

You can see the way this is extending here is more in keeping

5:46

with a meningioma.

5:48

Let's on the coronal and see whether there's a better demonstration on

5:53

dural tails or not. Yeah, this,

5:56

This kind of dural enhancement might be a good argument for

6:01

this. And notice the,

6:03

the vascular involvement here as we, uh,

6:07

see the posterior cerebral artery. So,

6:13

um, in this case,

6:16

the correct diagnosis was meningioma,

6:19

and what you saw with regard to the commentary was

6:25

a request to make note of the cranial nerves that were

6:30

involved by the meningioma in order to elevate your score to the

6:35

exceeds expectations. Um,

6:40

one person, uh,

6:41

was a pointed out the fact that there was a second meningioma,

6:47

so that person also got exceeds expectation. Two,

6:51

meningiomas do not make neurofibromatosis. Type two,

6:55

you have to have a single, uh,

6:58

in vestibular schwannoma plus a meningioma,

7:02

multiple meningiomas to, to make the criteria for NF two. But, um,

7:06

that was a nice pickup for somebody on the, uh, coronal image.

7:12

And this is a, actually a pretty nice review article,

7:15

not in a radiology journal, but the person did a good job.

7:18

This is from the NH N I H trust. And, um,

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in this she reviews the, the anatomy of the, you know, the,

7:28

the ninth 10 complex, the CP angle,

7:31

and the seventh eighth nerve complex. And, um,

7:36

you could see the anatomy on the cyst image again.

7:41

And then she starts looking at different pathology that can

7:45

occur in the cerebellum pontine angle. And, uh, does a pretty good job with, um,

7:50

Vista Omas as well as

7:56

some, uh, example of a facial nerve, Hema Angio,

7:59

which is this little bubbly lesion at the icic ganglion.

8:05

And then epidermoid cyst, which we will look at in just a moment.

8:10

This is still the cranial nerve here,

8:15

ninth, 10th nerve schwannoma,

8:17

which is in our differential with vestibular schwannomas as well as potentially

8:22

with our gloma tumors here. Um,

8:25

meningioma with the base along the, uh,

8:30

posterior fossa and with a little bit of a duro tail here is, uh,

8:35

a case that showed restricted diffusion and looked kind of dirty

8:41

cyst like, and this ended up being our epidermoid. This was an arachnoid cyst,

8:46

uh, lesion. And then, uh, some lipomas,

8:50

which are relatively unusual cases. So, um,

8:53

look over this article.

8:55

It seems like it's got nice illustrations of the different pathology

9:00

in this, uh, part of the anatomy.