0:00

This is the mid-sagittal

0:02

transfontanelle ultrasound

0:03

in a one day old child that

0:05

had an abnormal fetal ultrasound.

0:08

And on this,

0:10

we see some normal structures.

0:12

We see the corpus callosum,

0:14

see the midbrain,

0:16

the pons, the brainstem.

0:19

This is the cerebellar vermis.

0:21

But inferiorly,

0:22

we don't see the rest of the cerebellar vermis.

0:24

We see be something right here,

0:26

but it's not connected to the remainder

0:28

of the cerebellar vermis.

0:30

One tool that we have more recently in

0:34

evaluating the posterior cranial fossa

0:36

on neonatal head ultrasounds,

0:38

is this a transfontanelle view?

0:41

In this transfontanelle view,

0:43

this is somewhat of a sideways appearance.

0:46

This is one cerebellar hemisphere.

0:49

This is the other cerebellar hemisphere,

0:51

and there's a separation between them.

0:54

This is the fourth ventricle.

0:56

So, we start to have what

1:00

looks like a hypoplastic cerebellar vermis,

1:03

and one of the ways

1:06

to better characterize that is on MRI.

1:09

An MRI was performed at approximately

1:11

one year of life,

1:13

and if we were looking at the posterior fossa,

1:18

we can see the fourth ventricle posteriorly

1:24

connects to this CSF space here,

1:29

and there's some separation of

1:30

the cerebellar hemispheres,

1:33

and there's a hypoplastic cerebellar vermis.

1:36

If we look at the mid sagittal

1:40

T-1 weighted image,

1:41

we see the superior aspect

1:43

of the cerebellar vermis looks normal.

1:45

But inferiorly, it's missing.

1:48

This here is actually,

1:49

we can see on this axial image,

1:54

is portions of the cerebellar hemisphere

1:57

protruding into the midline

1:58

because there's no vermis

2:00

to take its place and push it to the side.

2:02

So, there's some cystic prominence of the

2:05

posterior cranial fossa in continuity with the

2:08

fourth ventricle and hypoplastic

2:12

cerebellar vermis.

2:14

Now, this is considered to be

2:17

in the Dandy Walker spectrum of malformations.

2:20

This is not a classic Dandy Walker malformation,

2:24

where the poster fossa is markedly dilated,

2:27

where there is more severe hypoplasia

2:32

of the cerebellar vermis and more uplifting

2:34

of the cerebellar vermis.

2:35

So, this is a moderate severity Dandy Walker

2:38

spectrum malformation.

2:40

In the past,

2:41

people referred to these as Dandy Walker variant,

2:44

but the term Dandy Walker variant,

2:46

to me is not appropriately descriptive.

2:50

It doesn't tell you how severe something is.

2:53

Dandy Walker variant could, to some people,

2:55

mean that 10% of the vermis

2:57

is missing or 50% or 90%

3:00

Well, I think this one,

3:02

approximately 50% of the cerebral vermis

3:04

is missing.

3:05

So to me,

3:06

this would be a moderate severity

3:08

Dandy Walker spectrum malformation.

3:10

Now, additionally, we can see,

3:13

this is the location of the nuchal ligament insertion.

3:16

Here is the torcula.

3:18

So, the torcula is slightly elevated from

3:21

the insertion of the nuchal ligament.

3:23

So, there is some enlargement of the

3:25

posterior cranial fossa,

3:26

but it is nowhere near as severe as in the

3:30

classic Dandy Walker malformations.