Interactive Transcript
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.
© 2024 MRI Online. All Rights Reserved.