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Let's talk about some tips for differentiating

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other genetic Chorea from Huntington's Chorea.

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One of these is HDL 2,

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and that one you can't differentiate radiographically

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but if you see somebody of African-American ancestry,

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you should be suspicious of that disease,

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and note this to the pathologist or whoever's

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doing the DNA sequencing.

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Prion disease, we discussed in another

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vignette, that in prion disease just sitting there

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persistently unchanging for a protracted period of

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time is relaxation prolongation that may involve

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the putamen or putamina bilaterally,

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but also the cortical areas.

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It may be symmetric or asymmetric.

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It does not enhance.

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Signal alterations in true Huntington's disease

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don't occur till much later on in the disorder in

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the caudoputaminal distribution

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and not in the cortex.

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Spinocerebellar ataxia, well, these are easy.

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You've got preferential disproportionate atrophy

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in the cerebellum.

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Not so in Huntington's Chorea.

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If we look at our case right here,

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there is some cerebellar atrophy, but it is not

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nearly as pronounced as the cortical and sylvian atrophy

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that we see in the supratentorial space.

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DPL, hard to say.

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Dentatorubral Pallidoluysian Atrophy is another CAG

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repeat disorder, and this is so rare that I

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often just lump it into the differential.

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But it is not distinguishable from Huntington's chorea

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very easily by imaging.

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Other rare disorders like ataxia-telangiectasia,

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they'll have abnormalities of the

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posterior fossa and telangiectasias,

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which makes the diagnosis a bit easier.

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Wilson's disease, they often have abnormalities

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of the thalamus bilaterally.

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You may see something called the big Panda sign,

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which we will be discussing a little bit later on.

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And they do not have the character of atrophy in

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the caudoputaminal distribution that you

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see in genetic Huntington's Chorea.

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And then finally, Holovorden-spatz disease,

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now known as pantothenate kinase-associated neural

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degeneration is associated with exaggerated

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iron stores in the globus pallidus,

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especially early on in the disorder and that

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should help you distinguish it from Huntington's Chorea,

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plus the symptoms are a bit different even though

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they might have a chorea-type movement disorder.

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Let's move on now to a discussion

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of Sydenham's chorea.