0:01

This is an eleven-year-old child

0:02

with neurofibromatosis type 1,

0:04

and we see asymmetric prominence of CSF

0:08

in the anterior aspect of the right middle cranial fossa.

0:11

Now, in children and in adults,

0:14

an arachnoid cyst at the anterior aspect of

0:16

the middle cranial fossa

0:17

is a very common entity,

0:19

and there likely is a cystic component in here,

0:23

but there's more to it than that.

0:25

In this patient,

0:26

if we look, this area here is the left

0:31

greater sphenoid wing.

0:32

We see a thin,

0:33

dark line anteriorly, representing cortex

0:37

along the posterior orbital wall.

0:39

We see a thin dark line here,

0:42

representing cortex at the anterior aspect of

0:46

the middle cranial fossa.

0:47

And the intermediate hyperintense signal here

0:51

is related to marrow within the sphenoid bone.

0:54

We're not seeing a corresponding

0:55

structure on the right side,

0:58

so there's either severe thinning or near

1:01

complete absence of the right greater sphenoid wing.

1:05

What's happening because of that?

1:07

Well, we're seeing the dura bulging in towards

1:10

the posterior aspect of the orbit,

1:13

and at least based upon imaging resolution,

1:16

is actually possibly pushing on the right

1:20

lateral rectus muscle.

1:21

This is the MR appearance of sphenoid wing dysplasia

1:26

in the setting of neurofibromatosis type 1.

1:28

Sphenoid wing dysplasia is one of the

1:30

characteristic findings that is often

1:33

described in neurofibromatosis type 1,

1:35

although it is not seen nearly as common

1:37

as some of the other findings.

1:39

But if you know what it looks like on MR,

1:41

you may be able to identify it.