0:01

This is an MRI of the brain

0:02

in a one-and-a-half-year-old child

0:03

that has clinical features

0:05

of neurofibromatosis type 1.

0:07

So the MRI of the brain is being performed

0:09

as a baseline evaluation and to see if

0:12

there's any intracranial manifestations.

0:15

So, we look at the classic places that

0:19

we look for myelin vacuolization.

0:21

We look at the globus pallidus,

0:23

and we're not definitely seeing it.

0:26

We look at the thalami,

0:27

and we're not seeing anything convincing.

0:32

We look at the brainstem,

0:34

we're not seeing any abnormalities.

0:36

And the cerebellum, we're not.

0:37

So, patients with neurofibromatosis type 1,

0:41

especially when they're young,

0:42

can actually have MRIs of the brain

0:44

that look normal.

0:46

But how do you report that?

0:48

What do you do when the geneticist or the

0:51

pediatrician sends you an MRI in a patient

0:53

where they clinically know the patient

0:56

has neurofibromatosis type 1?

0:57

And you're saying the MRI

0:59

of the brain is normal?

1:00

Well, those are not incompatible entities,

1:03

especially in young children,

1:05

there are definitely times where there is

1:09

either low lesion burden or normal.

1:13

So how do I report that,

1:15

and how do I tell them?

1:16

Well, if it's a known diagnosis

1:19

of neurofibromatosis type 1, I will say,

1:24

at the impression,

1:25

MRI of the brain is within normal limits.

1:28

But then I will follow it with

1:29

a statement such as,

1:30

there are no intracranial stigmata of

1:32

neurofibromatosis type 1 at the present time.

1:35

That's a way of sort of saying, well,

1:39

I know the patient has NF 1

1:41

because you told me that.

1:43

I know what NF 1 looks like

1:46

because this is one of the things that I do,

1:49

and I'm not seeing those things,

1:51

and you're not seeing them at the present

1:53

time is also sort of conveying

1:55

to them that, you know

1:57

that two or three years from now,

1:59

there may be lesions.

2:00

We know myelin vacuolization occurs over time.

2:03

We know that.

2:07

Now, this patient also,

2:09

their optic nerves,

2:12

this is something I would consider to be a

2:15

normal degree of tortuosity at this age,

2:18

but probably upper normal.

2:21

So, I don't know if I would necessarily

2:23

describe it in the report,

2:25

given that, if the patient has NF one,

2:29

that they're going to get follow-up exams.

2:32

But what if this was instead of a patient

2:36

that had a known diagnosis of NF 1,

2:39

what if this was a patient with some

2:41

Café-au-lait spots, some birthmarks that they said,

2:44

well, maybe they have NF 1?

2:46

Well, that's a little bit different.

2:48

And in that case,

2:49

saying there's subtle tortuosity of the

2:52

optic nerves without discrete lesion

2:55

at least can let them know,

2:57

well,

2:57

they may not have confirmed a diagnosis of NF 1,

3:00

but they should at least keep looking,

3:04

because it is very possible that the rest

3:08

of the brain doesn't show signs

3:10

of NF 1 at the present time.

3:12

This very subtle tortuosity of the optic

3:14

nerve could be the early manifestation

3:17

of NF 1 changes.

3:19

And if the patient didn't get continued

3:22

follow-up, they would never know.

3:25

So, just because an MRI of the brain

3:27

looks normal in NF 1,

3:29

that does not mean that the patient

3:31

doesn't have NF 1.

3:32

It just means that there's no macroscopic

3:34

manifestations at this time.

3:37

Now, while we're not seeing any discrete

3:39

lesions in the brainstem,

3:40

I'm going to zoom in, and we see these

3:43

paired hyperintense abnormalities right here.

3:46

What is this?

3:47

Is this myelin vacuolization?

3:50

It's not.

3:52

So if we look at the brainstem anatomy,

3:54

here's the midbrain, the pons,

3:57

the medulla,

3:58

and where the pons and the medulla join

4:02

is the pontomedullary sulcus.

4:04

And this right here is volume averaging of

4:09

CSF within the lateral aspect

4:11

of the pontomedullary sulcus.

4:12

So, this does not represent areas

4:14

of myelin vacuolization.

4:16

So this patient, again,

4:18

does not have any discrete convincing

4:21

lesions of myelin vacuolization

4:23

at the present time.