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Let's attack some measurements

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in Huntington's Chorea.

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Let's begin with the frontal horn width,

0:06

which is obvious,

0:06

depicted here with a green line.

0:08

I'm going to draw over it just so you've got it.

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From the tips of both frontal horns,

0:13

best seen in a slice or two below

0:16

the ventricular body.

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So that's going to be your frontal horn width.

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Then you've got your inner table width,

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which I would draw at the maximal indentation

0:26

of the caudate, which is right here.

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So, I'm going to use a different color for that.

0:30

Let's try something yellow.

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You go from inner table to inner table.

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So that'll be another measurement.

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Then your final measurement,

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which is depicted by these two

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little tick marks here,

0:43

is the intercaudate distance where the caudate

0:45

pinches in the frontal horns of the lateral

0:48

ventricles, most prominently.

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I'm going to use pink for that.

0:52

And that is going to be your intercaudate distance.

0:56

Now, in Huntington's Chorea,

0:58

because the caudate gets so atrophic,

1:00

it dominates the ratios I'm about to give you.

1:03

So we take the intercaudate distance,

1:06

which is this pink line right here,

1:08

and you divide it by the inner table distance,

1:11

which is the yellow line.

1:13

The normal ratio is somewhere between 0.09 and 0.12.

1:19

As the patient becomes more afflicted with a

1:24

disorder that causes widening of

1:26

the intercaudate distance,

1:27

this number is going to go up, this ratio number,

1:30

and in our case,

1:31

the ratio was 0.16 or elevated.

1:36

The other ratio that's used is the frontal horn

1:40

distance divided by the intercaudate distance.

1:44

Now, since the intercaudate distance

1:46

is in the denominator,

1:47

so it'd be frontal horn

1:50

over intercaudate distance.

1:52

As this number goes up faster

1:54

than the widening of the frontal horn,

1:56

so this will get greater,

1:57

this will get greater, but this will get greater faster.

2:01

This number or ratio is going to go down.

2:04

So the normal range ratio is 2.2 to 2.6,

2:10

and in our case, it's 1.62.

2:13

So, it's decreased because the intercaudate

2:16

distance is rising faster than

2:18

the frontal horn distance,

2:20

even though there is some frontal

2:22

component atrophy.

2:24

So, the intercaudate distance

2:25

dominates these ratios, and they can be

2:29

used to assess subjectively and objectively,

2:33

the character of the caudate and

2:36

surrounding structures.

2:37

So now, let's move on to a bit of a clinical

2:39

discussion of Huntington's Chorea now that

2:42

we have those basic measurements.