0:01

It's important,

0:02

when discussing classic Parkinson's disease or PD,

0:05

to have an understanding of brain

0:08

iron distribution stores.

0:10

Now, brain iron doesn't start to accumulate until

0:14

about 12 or 13 years of age.

0:16

And there are typical territories,

0:18

many of which I'm showing you here on this coronal

0:22

pathologic anatomic specimen of a real brain,

0:26

demonstrating brain iron staining,

0:29

including the caudoputamenal

0:31

or corpus striatum region.

0:33

You're seeing the head and body of the caudate nucleus.

0:36

And yes, there is a tail,

0:38

there is an inner and outer aspect of the putamen.

0:41

We actually can't subdivide these

0:43

on this particular stain,

0:45

but outside the putamen is the external capsule,

0:48

devoid of iron, then the gray matter,

0:51

claustrum with iron, then the extreme capsule,

0:55

and then the centro sylvian cortex.

0:58

The globus pallidus,

0:59

has variable amounts of iron with a GPI,

1:03

the globus pallidus inner component, and a GPE,

1:07

the globus pallidus external component.

1:10

The GPI demonstrates or exerts a restraint on

1:16

secretory behavior and nerve behavior

1:20

in the thalamus and in the midbrain.

1:22

And it's the loss of this restraint that

1:25

accounts for many movement disorders.

1:28

Now, we're able to separate the GPE from

1:30

the GPI, external from internal,

1:33

and that moves us over towards the midbrain,

1:36

where we have the nucleus ruber or red nucleus,

1:40

and the substantia nigra.

1:42

Now, in the normal setting,

1:43

we see the reticular layer of the substantia nigra,

1:47

which is this outer component right here,

1:50

and then the nucleus ruber,

1:52

or red nucleus, right there.

1:53

And they are separated by a non-stained area,

1:57

which will show up less dark on the MRI because

2:01

of the paucity of iron present.

2:03

But when iron accumulates in this area,

2:06

I'll make it a slightly different color,

2:08

maybe a little orange.

2:10

As iron accumulates right in the middle,

2:13

these two areas will start to bleed together

2:15

and this stripe is then lost.

2:18

That is one of the signs of classic Parkinson's disease.

2:22

Now, unfortunately,

2:23

it doesn't have a very high specificity for it,

2:27

but in mid to late-stage Parkinson's disease,

2:30

the absence of it is an important distinguisher

2:34

of pseudoparkinsonian syndromes.

2:37

So, you would like to see it in

2:39

mid to late-stage disease.

2:41

We'll also talk about the medio-lateral extent

2:44

of accumulation of iron in the nigrostriatal

2:49

distribution in the axial projection

2:52

in the next vignette.

2:53

Let's move on, shall we?