0:01

This is a CT scan in a five-year-old boy

0:03

with seizures.

0:04

We can already see several areas

0:06

of calcification, both along the

0:08

margins of the lateral ventricles

0:10

and in the frontal parenchyma.

0:12

Let's look a little closer.

0:14

In addition to these two areas of

0:17

calcification, we're seeing a speck along

0:20

the margin of the frontal horn of the

0:22

left lateral ventricle, along the lateral

0:24

margin of the body of the left lateral

0:26

ventricle, the supralateral margin of

0:28

the body of the right lateral ventricle.

0:30

There's a number of these beyond those.

0:34

calcifications along the margins

0:35

of the lateral ventricle.

0:37

There is this parenchymal calcification here

0:40

at the depth of the sulcus, the gray-white

0:42

differentiation in the left frontal lobe.

0:46

Let's further evaluate this patient

0:48

with MRI, and we can see multiple

0:52

areas of flare hyperintense signal

0:57

throughout both cerebral hemispheres.

1:00

If we look closely at these flare signal

1:02

abnormalities, we can see that there

1:07

is this signal abnormality that tapers

1:09

as it extends into the super lateral

1:12

margin of the lateral ventricles.

1:14

So it's this flare hyperintense

1:15

signal that migrates out and fans

1:20

out as it gets out peripherally.

1:22

We look at another lesion, we'll see it fans.

1:28

Similar here.

1:30

What does that mean?

1:32

Well, these are manifestations

1:34

of tuberous sclerosis complex.

1:36

In particular, these areas here

1:38

are called cortical tubers.

1:40

The bright signal adjacent to the

1:42

tuber is related to dysplastic cells,

1:46

and this area of dysplasia is what's

1:50

referred to as a cortical tuber.

1:54

These cortical tubers.

1:56

Are histologically and radiologically

1:59

identical to what's known as focal cortical

2:02

dysplasia Type II B, which is sometimes

2:04

also referred to as the Taylor type of

2:07

focal cortical dysplasia and also focal

2:10

cortical dysplasia with balloon cells.

2:13

That's because the dysmorphic

2:14

neurons look sort of like balloons.

2:18

These areas of cortical dysplasia

2:20

or cortical tubers on the surface

2:22

look like little protuberances.

2:25

Tubers, and they are firm to the touch.

2:30

First identified on autopsy by Dr.

2:33

Bourneville.

2:34

And so by being firm or rigid, it's sclerosis.

2:38

So these tuberous sclerosis

2:40

comes from this here.

2:43

We often refer to the disease clinically

2:45

as tuberous sclerosis complex because

2:47

it is more than just these areas

2:49

of dysplasia or cortical tubers.

2:51

And we're going to discuss

2:53

some of those differences.

2:57

So we see these multifocal multifocal

3:00

areas of cortical dysplasia

3:02

throughout both cerebral hemispheres.

3:05

Each one of these areas of cortical

3:07

dysplasia is a potential source of a seizure.

3:12

Now, beyond the cortical dysplasia,

3:15

of which this one here is mineralized,

3:18

we have multiple little nodules along

3:20

the margins of the lateral ventricles.

3:23

We can see on T2-weighted image, these two

3:25

nodules here, along the lateral margin of

3:29

the anterior body of both lateral ventricles,

3:31

are hypointense on T2-weighted imaging.

3:34

This T2 hypointensity is related to the

3:37

low water content that we can surmise from

3:39

the mineralization seen on the CT scan.

3:41

Susceptibility weighted imaging shows

3:43

hypointense signal also, which is the

3:46

MR correlate of this mineralization.

3:50

Susceptibility-weighted imaging also shows

3:52

some of these other areas of mineralization,

3:54

including this one along the margin of the

3:56

frontal horn of the left lateral ventricle

3:58

and that area of mineralized dysplasia.

4:02

After giving contrast, we can see that

4:04

surrounding this area of mineralization

4:08

along the lateral margin of the frontal

4:09

horn of the right lateral ventricle,

4:12

there's post-contrast enhancement.

4:15

We can see here there's post

4:17

contrast enhancement, and

4:18

there's a hypo-enhancing area.

4:20

This hypo-enhancing area is likely the

4:22

mineralization because calcium does not have

4:25

blood vessels and therefore does not enhance.

4:29

So we can measure this nodule, and including

4:35

the mineralization, it's approximately

4:37

one centimeter by one centimeter by

4:42

That's approximately six millimeters.

4:45

These nodules, many of which

4:46

demonstrate mineralization, are

4:48

called subependymal nodules.

4:50

They're a key feature of

4:51

tuberous sclerosis complex.

4:54

These nodules may also enhance, but one

4:58

thing to be aware of is that some of

5:00

these nodules, in particular ones along

5:03

the lateral margin of the anterior body

5:05

of the lateral ventricles, can enlarge.

5:08

They enlarge and are clinically referred to

5:11

as a subependymal giant cell astrocytoma.

5:15

That can become a problem if they get

5:17

too big because, as we notice, this

5:19

is adjacent to the foramen of Monroe.

5:23

If this enlarges too much, it can obstruct

5:26

the ipsilateral foramen of Monroe and

5:29

result in obstructive hydrocephalus.

5:33

So if we look at a follow-up study, five years

5:37

later, we can see that this nodule has grown.

5:40

There's still this area of hypo enhancement,

5:43

likely related to mineralization, but the

5:45

surrounding area of tissue, has enlarged.

5:50

It's now at least 15 millimeters.

5:54

Now, at the moment, the ipsilateral

5:56

foramen of Monroe does not appear to be,

5:59

be obstructed, although this is something

6:03

that they want to keep a very close eye on,

6:06

because if there is enlargement to the point

6:09

where there's impending impingement of the

6:10

foramen of Monroe, there are several options.

6:13

Historically, surgical

6:14

resection was the option used.

6:16

More recently, we know that mTOR

6:19

inhibitors mTOR, meaning mammalian

6:22

target of rapamycin, M T O R.

6:24

MTOR inhibitors can actually result

6:28

in involution of the lesions and

6:32

may obviate the need for surgery.

6:35

So this patient has tuberous

6:36

sclerosis complex with a right-sided

6:39

subependymal giant cell astrocytoma.

6:43

Now, it's important to notice that this lesion

6:46

was 10 millimeters and it took over five years

6:49

for it to get large enough that it's even

6:52

getting close to the frame of the Monroe.

6:57

A lot of times there are distinctions

7:00

made that once a lesion reaches 10

7:02

millimeters, it's a subependymal giant

7:04

cell astrocytoma or SEGA, S E G A,

7:08

but That doesn't tell the whole story.

7:12

An eight-millimeter nodule and a

7:14

12-millimeter nodule histologically

7:16

are going to be identical.

7:17

If you give it to the pathologist and don't

7:20

tell them how big it is, they're going

7:21

to call both of them the same, a SEGA.

7:24

So we need to recognize that there's

7:27

a difference between the histological

7:28

diagnosis of the SEGA and the

7:31

clinically relevant diagnosis.

7:33

From a clinically relevant standpoint, people

7:35

have historically said 10 millimeters.

7:38

Recognize, of course, that a lesion

7:40

that has been 11 millimeters for five

7:45

straight years without any growth.

7:47

While it is greater than that 10

7:49

millimeter threshold, likely is

7:52

not of immediate clinical concern.

7:56

Conversely, a lesion that is two millimeters

7:59

that six months later is four millimeters

8:01

that six months later is six millimeters

8:03

that six months later is eight millimeters.

8:06

That's more concerning.

8:07

So even though it hasn't reached

8:08

the 10 millimeter threshold, the

8:10

growth trajectory is actually just as

8:14

clinically relevant as the actual size.

8:16

So beyond just reporting the size of

8:19

a lesion, the growth trajectory, as

8:23

well as the relationship to the foramen

8:24

of Monroe is critically important.