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Hi, I'm Dr. Stephen Pomeranz.

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This is my young colleague,

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Dr. Ben Laser.

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We're here to talk about neurodegenerative

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disease of the brain.

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We've got a 58-year-old with kind of a weird history,

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mostly speech disturbance.

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And there is an abnormality in the

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corona radiata on the left.

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Perhaps the speech disturbance is vascular.

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There's a rather complex history,

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which I won't go into now,

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but there is an obvious finding on the sagittal scout

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T1-weighted image or set of findings.

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And what is that set of findings?

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Well, the most obvious finding is

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marked atrophy of the pons,

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marked atrophy of the cerebellum.

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You can see that the pontine belly is flattened.

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There's a little tiny nubbin perturbance on the front,

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which is abnormal.

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This thing right here?

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That little thing right there.

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Sure.

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The fourth ventricle is markedly gapped widened.

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There's no mass lesions,

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so there's no obstruction below.

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So, the takeaway point for this image is that

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there's this marked atrophy of the

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pons and of the cerebellum.

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So this is all ex vacuo enlargement.

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You've got this gaping inferior fourth.

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The area of the obex has this huge

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channel running through it.

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And then when you look up high,

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there's no obstructive hydrocephalus

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particularly important.

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So we have pontocerebellar atrophy.

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And you think about heredofamilial

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forms of pontocerebellar atrophy,

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but maybe not in a 58 to 60-year-old.

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That patient's a little old for that condition.

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Then another interesting point is that the

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colliculi, especially a superior colliculus,

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nice and juicy.

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And one diagnosis you might think of would be

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progressive supranuclear palsy with a hummingbird

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sign with marked atrophy of the mammillary body

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doesn't have that,

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and he's got a very juicy superior colliculus.

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So PSP, progressive supranuclear palsy.

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Not a go od explanation

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for this pattern of pontocerebellar atrophy.

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So, Dr. Lasar, tell me,

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are there any measurements that you can use to

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differentiate, say, PSP from multisystem atrophy,

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which is one of the differential diagnostic

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considerations here?

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There is.

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In terms of PSP,

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looking at the midbrain to pons ratio,

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one thing that you can do is you can actually draw

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a line along the pontomesencephalic junction,

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which is essentially a line between the superior

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pontine notch and the inferior border of the

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quadrigeminal plate.

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Okay, I got that line.

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Then I'm going to draw the rest of the midbrain.

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So, I got my midbrain tracing.

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Now, what about the pontine tracing?

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So the pontine tracing,

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you would draw a line at the pontomedullary junction

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which is aligned parallel to the first line at

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the level of the inferior pontine notch.

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And you kind of include the rest of it here,

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and then you come up with a ratio.

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And typically, what's the ratio in PSP?

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A normal ratio in this area would be 0.24.

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Typically, anything below that,

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0.12 would be a common thing seen in PSP.

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In progressive supernuclear palsy.

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Correct.

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So it's midbrain over pons, is the ratio.

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Yup.

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Okay, so let's do away with that for now.

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Let me point out another sort of little pitfall here.

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When you're in the midline,

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the colliculi look really small.

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And that's because if you look in the axial projection,

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the collicular plate looks like this.

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It's kind of a bumpy looking thing.

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And here's the colliculus.

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I'm going to draw over it.

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So the bumps are off to the side.

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So if you're right in the midline,

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you're going to catch this depression right here.

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And when you do that,

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the depression makes it look like the

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collicular plate is very small.

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I've seen a lot of young radiologists just go down

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the tubes on that. But as you go off to the side,

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watch us go off to the side.

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Big, fat, juicy, superior colliculus.

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Pretty good inferior coliculus.

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Go to the other side.

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Big, fat, juicy one again.

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We are not dealing with PSP.

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Therefore, multisystem atrophy would be

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a strong or favored consideration.

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So what are the types of multisystem atrophy?

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So, the two main types of multisystem atrophy

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are type P and type C.

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Type C typically stands for cerebellar.

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Okay, we got a lot of cerebellar atrophy here.

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And type P would be a Parkinsonian type picture.

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Sure, most people think P stands for pons.

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You know, you got this funny little notch here, but no,

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it stands for Parkinson's like.

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Now, one reason,

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one very important clinical reason to

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differentiate these two is you can treat

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Parkinson's patients with L-Dopa or Sinemet

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and they respond.

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Patients with MSA don't respond,

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and they may suffer from some nasty complications

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of dopaminergic therapy.

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So you don't want to treat them

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unless they are responders.

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And then when we look at the axial projection,

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I'm going to blow it up a little bit.

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This is an axial T2.

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I'll just scroll it for a bit in the middle.

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And on the far right is a susceptibility weighted

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image or a blood sensitive image, SWI, BSI,

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venous bold, or SWAN.

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And it is very sensitive for iron and

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calcium and hemosiderin and blood.

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And as we go to the substantial nigra level,

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let's do that and try and separate out the

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red nucleus from the substantia nigra.

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I'm going to make it a lot bigger.

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And I have...

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there's the red nucleus.

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There is the compacta stripe.

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And that whitish compacta stripe,

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a little more narrow on the right than it is on the left.

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So, it's not perfect.

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There's the substantia nigra.

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And when you look at the axial blood-sensitive image,

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I'm going to blow that one up.

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You'll see that you have a nice round iron

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collection on the left.

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On the right,

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the substantia nigra and the red nucleus

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sort of start to bleed together.

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So there probably is a Parkinsonian

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component to this case.

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So, most likely, we're dealing with a combination

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of MSAC and MSAP,

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the Parkinson's type.

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Now, just a few closing comments about this case.

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Multisystem atrophy has numerous subtypes.

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The only one we've left out is MSAA,

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the autonomic type.

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Those patients often have orthostatic hypotension.

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They usually can't stand in one place.

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They can walk because the contraction of the

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muscles keeps their blood pressure up.

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But if they stand there in one location,

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they can often have syncopal episodes from hypotension.

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And then pathologically,

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there's degeneration of the striatum,

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as there is here.

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The substantia nigra, the cerebellum, the pons,

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as we have here.

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And then pathologically,

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you'll see alpha-synuclein inclusions in

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the oligodendroglia.

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So this is MSAC,

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maybe with a component of MSAP,

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to be differentiated from classic Parkinson's disease

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and from progressive supranuclear palsy,

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which is associated with a lot of collicular plate atrophy.

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Don't have it here.

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Sometimes the hummingbird sign,

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don't have it here.

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Let's check out on this one, shall we?

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We shall.

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Laser and Pomeranz out.