0:00

This is a head ultrasound on a newborn that had

0:04

an abnormal fetal ultrasound with concern for an

0:09

abnormal development of the

0:10

posterior cranial fossa.

0:12

And similar to the fetal ultrasound,

0:17

it can be difficult to fully characterize the

0:20

cerebellar vermis.

0:21

Here's the fourth ventricle,

0:23

and this is the cerebellar vermis.

0:25

And it's hard to know where the

0:27

cerebellar vermis stops.

0:29

So, this is definitely a time where

0:32

MRI is more beneficial.

0:36

In this case,

0:37

we can see there is hypoplasia of the inferior

0:42

aspect of the cerebellar vermis,

0:44

but the vermis is present nearly in its entirety.

0:47

We can see the superior medullary velum,

0:50

right here, inferior medullary velum.

0:52

A normal cerebellar vermis looks sort

0:55

of like the character for Pac-Man.

0:57

It's about trying to eat the brainstem.

1:00

And in this case, most of Pac-Man is here,

1:03

except Pac-Man has micrognathia.

1:05

There is a hypoplastic inferior portion

1:09

of the cerebellar vermis.

1:10

So, there's just a very mild inferior vermian

1:14

hypoplasia and mild enlargement of

1:18

the posterior cranial fossa,

1:20

where this CSF space is in free continuity

1:23

with the fourth ventricle.

1:25

So we can look at this on a T2-weighted image

1:30

axial here, and you can see inferiorly,

1:34

we're not seeing any cerebellar vermis

1:37

between the cerebellar hemispheres.

1:40

Superiorly,

1:41

we see a normal vermis.

1:42

So, this is a case where there's near complete

1:46

development of the cerebellar vermis.

1:49

But while it's nearly completely there,

1:54

people sometimes referred to this

1:55

as a Dandy-Walker variant.

1:57

The problem is that a Dandy-Walker variant

2:00

doesn't tell you if this is a mild hypoplasia of

2:05

the vermis or more moderate or more severe

2:07

hypoplasia of the cerebellar vermis.

2:09

This case,

2:10

I would consider it to be a very mild

2:12

Dandy-Walker spectrum malformation,

2:14

and I avoid the term Dandy-Walker variant

2:17

because it is not a single entity.

2:20

But if we qualify the description of this as

2:25

being a mild Dandy-Walker spectrum malformation,

2:28

I think it gives appropriate description to

2:32

whoever's reading it that there are some

2:35

features in the Dandy-Walker spectrum,

2:37

but it is milder.

2:39

I think that's important because there's a lot

2:43

of confusion about terminology of the posterior

2:45

cranial fossa malformations. In particular,

2:47

the Dandy-Walker spectrum malformations.

2:50

And not every person is going to

2:52

say the exact same thing.

2:54

And,

2:55

you know,

2:56

not every book that you read is

2:58

going to say the same thing.

2:59

So, if you're appropriately descriptive

3:03

saying a mild severity Dandy-Walker spectrum

3:06

malformation, I think that's helpful.

3:08

I think that's appropriately descriptive.

3:10

And by such as this,

3:13

very often, can be clinically silent.