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This is a 67-year-old man who presents with

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abnormal fine motor skills and a strong family

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history, namely that of Huntington's chorea.

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I think you're all first struck on this T1 FLAIR,

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also a T1 with contrast,

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a T1 spin echo on your left,

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by the atrophy,

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especially in the Sylvian region,

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but throughout the brain, it's generalized atrophy.

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What you should also be struck by is the fact that

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even though there's generalized atrophy,

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there's not much atrophy in the entorhinal cortex,

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which is right here.

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Yes, the temporal horns are a little bit generous,

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the choroidal fissures are a little bit generous,

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but compared with the atrophy elsewhere,

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they're much less conspicuously present,

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than when you know the history,

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which makes it a lot easier.

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But without the history,

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you always want to be looking at the size

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of the corpus striatal structures.

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And in prior vignettes,

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you have seen the caudate nucleus.

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Look how small the caudate nucleus is,

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especially look at the lack of width from medial to lateral.

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And with that lack of width,

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the frontal horns bow out laterally because

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there's no structure there to restrain them.

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Look at the lack of substantive meat structure

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or width to the region of the putamen,

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which is right here.

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Should be a nice curvilinear lentiform structure.

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If I draw over, it looks a little bit like this.

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I'm going to draw the triangle right here and

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in that triangle is the globus pallidus.

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I'll make that a different color.

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And then look at what's left for the putamen.

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Not much at all.

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You can kind of hallucinate these same

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structures on the opposite side.

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So there's thinning or thinness of the putamen.

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There's certainly mediolateral thinning

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of the caudate nucleus.

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Now, let's pull down some axials and see if

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we can corroborate original thought.

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I've got an axial T2 fast spin echo,

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an axial STIR,

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and an axial T1-weighted image.

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Probably the T1 is the least useful of the three.

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Let's focus on these two right here.

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We see a little bit of brain

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iron in the GPi and GPe,

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the internal and external aspect of the globus pallidus,

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which blends with the retro lentiform

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portion of the internal capsule.

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There is the putamen looking relatively

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small on both sides on the FLAIR.

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But look at how tiny the caudate nucleus is.

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Then as we come up to the frontal horns,

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you can hardly even see a caudate nucleus next to

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the frontal horns and the frontal

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horns are bowing laterally.

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Later on we'll talk about the intercaudate distance

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ratios, the frontal horn distance, and so on.

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But the take-home message here is you

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have a generalized pattern of

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atrophy that even involves the cerebellum,

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although not as much.

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But there is lesser degrees of involvement in the

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inferior aspect of the brain in the region

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known as the entorhinal cortex.

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And I'll show it to you one more

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time on the FLAIR image.

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Here is your entorhinal cortex which consists of

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about six or seven other structures that we'll

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delve into later on.

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So the temporal horns,

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not as big as you would expect.

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The choroidal fissures,

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not as big as you would expect in somebody with

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Alzheimer's disease, and the history isn't

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quite so good for that.

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Namely,

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the patient's primary symptoms are related to a

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movement disorder and a genetic disorder

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and that is Huntington's disease.

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Now, Huntington's disease results in a neurophysiologic

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imbalance that causes chorea.

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There are many different causes of chorea,

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diverse causes.

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Infections, I've seen HIV cause it.

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I've seen rubella cause it.

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The classic cause is endocarditis.

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It can be caused by trauma, by autoimmune disease.

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The classic is primary intracranial

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leukocytoclastic vasculitis or systemic lupus

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erythematosus, genetic mutations or

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neurodegenerative diseases like Huntington's chorea,

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stroke, tumors, drug exposure.

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The typical drug is the one used to treat the

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tremor of Parkinson's disease and several

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metabolic disorders of which actually, in a way,

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Huntington's chorea is a metabolic disorder,

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at least in the end game,

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as a result of the genetic

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abnormalities and abnormality of metabolism results.

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Let's move on and talk more about

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Huntington's disease.