Interactive Transcript
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Let's take a look at this case and analyze it
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because the patient presented with vocal
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cord paresis on the left side.
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Here we have a mass that is situated
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at the skull base.
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And we notice that the lesion appears to grow into
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the jugular foramen.
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So at first blush,
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we might say, well, you know,
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is this a glomus jugulare tumor?
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It's growing from the skull base down into
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the carotid sheath.
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From that standpoint, it meets the criteria.
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On the post-gadolinium-enhanced scan,
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it is an enhancing lesion.
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You can see it coursing into the jugular foramen
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and even down here at the edge
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of the hypoglossal canal.
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This is the hypoglossal canal seen here,
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and that also can occur with glomus jugulare tumors.
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However, what we should be focusing on
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is the presence of the jugular vein,
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posterior lateral to this mass.
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This jugular vein is compressed,
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but the tumor is not growing into the jugular vein.
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Here's the jugular vein there.
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In point of fact,
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it is anterior medial to the jugular vein.
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Here again,
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we see the flow void of the jugular vein here.
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Next thing to ask is where is the carotid artery?
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Here we have our carotid artery bifurcation,
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and we see that the internal carotid artery is coursing
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along the anterior medial border of this mass.
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That would argue that this is
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not a carotid body tumor,
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which should have the internal carotid artery
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along the posterior edge of the tumor,
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separating from the external carotid artery.
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This kind of intermediate signal intensity tissue
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is pretty typical of Antoni A,
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dominant schwannoma tissue.
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The brighter signal intensity,
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more likely the antony B.
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So this, by virtue of the anterior medial displacement of
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the internal carotid artery and the posterior
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lateral displacement of the jugular vein,
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argues that this is a vagus schwannoma.
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But what about the involvement
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of the jugular foramen?
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The vagus nerve comes through the pars
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vascularis of the jugular foramen.
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The 9th cranial nerve comes through the
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pars nervosa of the jugular foramen.
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But the jugular foramen involvement does
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not exclude a vagus schwannoma.
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Let's make sure that we can see these vascular
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displacements on our sagittal scan.
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Here we have the sagittal scan,
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again, showing the internal carotid artery,
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as we saw in a previous case,
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being displaced anteriorly by the tumor.
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Identifying this as more likely a vagus schwannoma.
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The jugular vein is seen over here.
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It's being compressed.
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I can't really identify it very well.
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Let's see whether it's better on the sagittal
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T2-weighted scan for the jugular vein.
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Not well identified.
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How about over here?
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A little bit of the jugular vein over here,
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but not as well seen.
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Here's the jugular. Jugular. Can't see it.
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In any case,
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the preponderance of evidence here is that this
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represents a vagus schwannoma that is growing
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into the jugular foramen.
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