0:00

This is an MRI of the brain in an eight-year-old

0:03

female that was performed for headaches.

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And at first glance,

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all the major things that we look for are normal.

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The ventricles are normal in size.

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We're not seeing any mass.

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Now,

0:14

notice you can see some movement artifact on this.

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This is very common in children,

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especially at around the eight-year age.

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Younger than that,

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we often sedate patients.

0:25

Older than that, they can hold still.

0:27

This small amount of motion artifact

0:29

is actually, I think,

0:30

an acceptable amount of artifact that allows

0:34

this child to have an MRI scan

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without needing sedation.

0:39

I think it's worth that we won't miss anything

0:42

if we look carefully at all the sequences.

0:45

Now, as we go inferiorly towards the

0:48

level of the foramen magnum,

0:50

we're seeing the cerebellar tonsils at the level

0:52

of the foramen magnum around the brainstem.

0:55

We're seeing fullness here.

0:57

That's then better characterized

0:59

on this sagittal image.

1:01

On this sagittal image,

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we can see the basion,

1:05

which is the inferior aspect of the basiocciput,

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representing the anterior margin

1:09

of the foramen magnum,

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and we see the opisthion.

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This is also part of the occipital bone that

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represents the posterior margin

1:17

of the foramen magnum.

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If we draw a line between the

1:21

basion and the opisthion,

1:23

we can measure the extent of cerebellar

1:26

tonsillar ectopia.

1:27

In this case,

1:28

the cerebellar tonsils extend

1:30

approximately 13 mm below the plane

1:31

of the foramen magnum.

1:33

But beyond that,

1:34

we're also seeing a contour abnormality in

1:36

the posterior aspect of the spinal cord.

1:39

This is in conjunction with

1:43

a paucity of CSF spaces.

1:45

There is near-complete effacement

1:47

of the CSF space ventral

1:50

to the cervical medullary junction

1:52

at the level of the foramen magnum.

1:54

There's a slightly retroflexed odontoid process,

1:57

and we're seeing effacement of the cisterna magna.

2:01

So, there's a paucity of CSF spaces here.

2:05

So, one of the things commonly that can

2:07

be performed is a CSF flow study

2:10

to look at CSF flow dynamics.

2:12

An additional follow-up study can be

2:15

imaging of the cervical spine.

2:17

You may not have time to do them initially when

2:20

you're first identifying this, but at follow-up,

2:23

you can.

2:24

But beyond those findings,

2:27

we need to look at all the images we have available,

2:30

all the data we have available.

2:32

And if we look in this sagittal image,

2:34

we can actually see here

2:36

syringohydromyelia in the mid-cervical cord.

2:40

This is a CSF collection within the

2:43

central canal of the spinal cord.

2:46

So, even though this is a dedicated brain study,

2:49

we can actually see this abnormality here.

2:52

So, from my perspective, yes, we can,

2:55

at follow-up, perform a CSF flow study,

2:58

but they've already failed.

2:59

The physiologic CSF flow study.

3:02

We already know there's an abnormal CSF flow

3:04

dynamics at the level of the foramen magnum.

3:06

Now,

3:06

spine imaging becomes important to understand

3:09

the caudal extent of this,

3:10

because we're not imaging this

3:12

syringohydromyelia in its entirety.

3:15

So this patient has a Chiari Type I malformation

3:21

with 13 mm of cerebellar tonsillar ectopia.

3:25

But we already know they have

3:28

syringohydromyelia.

3:29

So, this is a patient who likely would not

3:33

benefit from conservative management and may

3:37

require a posterior fossa decompression.