0:01

This is a 16-year-old

0:02

with no neurofibromatosis type 2.

0:05

We see bilateral vestibular schwannomas

0:07

where there is filling and expansion

0:10

of the internal auditory canals,

0:12

expansion of the porous acusticus,

0:14

more on the right,

0:15

and a component of the lesion that extends

0:18

into the cerebellar pontine angle cistern

0:20

and results in mass effect upon

0:22

the brainstem and the lateral aspect

0:24

of the middle cerebellar peduncles.

0:26

So, we look closely at the rest of the study,

0:30

we see there is an enhancing lesion

0:35

in the right cavernous sinus.

0:37

What is this?

0:38

Well, there's more than one possibility.

0:41

So, neurofibromatosis type 2.

0:45

We tend to think of as being bilateral

0:48

vestibular schwannomas,

0:49

but they can have schwannomas of

0:51

multiple other cranial nerves,

0:53

and it's known that cranial nerves three

0:56

and four are associated with the lateral

0:59

aspect of the cavernous sinus

1:01

and cranial nerve six, the abducens nerve,

1:05

goes through the cavernous sinus,

1:07

but this doesn't look exactly like

1:10

I would typically expect a schwannoma to look.

1:13

So, neurofibromatosis type 2 also has

1:17

association with other lesions.

1:19

In particular, intracranial meningiomas.

1:21

And this looks very much like what

1:25

we would expect a cavernous sinus

1:27

meningioma to look like.

1:28

So, while we do not have histologic confirmation,

1:31

it's very possible this is a cavernous sinus meningioma.

1:37

Neurofibromatosis type 2 patients also

1:39

get intramedullary spinal cord ependymomas.

1:43

So, while the name is neurofibromatosis type 2,

1:48

there is a name that has been proposed

1:51

of multiple inherited schwannomas,

1:53

meningiomas, and ependymomas.

1:55

M-I-S-M-E, or MISME.

1:58

Now, most people and most of the literature

2:00

will still know it and refer to it

2:03

as neurofibromatosis type 2.

2:04

So, it's important to use that terminology.

2:08

But the MISME syndrome,

2:10

or multiple inherited schwannomas,

2:12

meningiomas, and ependymomas,

2:14

it's important to be aware of that

2:15

because to be on the lookout for

2:17

meningiomas and other findings.

2:19

Now, this patient also,

2:21

we see this lesion in the anterior

2:23

aspect of the left optic nerve sheath.

2:25

If we look on this coronal T1 post contrast image

2:31

and this coronal STIR image,

2:33

we're seeing some expansion there.

2:36

That's a little bit puzzling and that's

2:39

admittedly not a characteristic finding

2:42

of neurofibromatosis type 2,

2:45

but it is something that warrants surveillance.

2:49

It also warrants genetic evaluation

2:52

for other entities because, again,

2:55

this is not explained by the typical

2:57

findings of neurofibromatosis type 2.

3:00

So, it shows that beyond the characteristic findings

3:03

of a given entity,

3:04

we have to be on the lookout for other things

3:06

that the patient may have.

3:08

So, this patient has neurofibromatosis type 2

3:12

with bilateral vestibular schwannomas,

3:13

a right cavernous sinus lesion,

3:16

presumably meningioma,

3:17

and a left optic nerve sheath lesion

3:19

of unknown etiology, at this point.