Interactive Transcript
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This is an MRI of the brain in a six-year-old
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female that was performed for abnormal gait.
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And superintendentially,
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we can see the lateral ventricles are
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slightly larger than usually seen.
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The third ventricle
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is also upper normal in caliber.
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But the rest of the brain,
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parenchyma looks fairly normal.
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But if we go to the posterior fossa,
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there's an abnormality that,
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at first, can be difficult to identify,
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because anytime you have either a bilateral
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symmetric abnormality or an abnormality in the
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midline, it can be very challenging to identify.
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And I think it's actually easier to see this
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sometimes on a coronal view,
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where we see there's midline continuity
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between the cerebellar hemispheres.
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There normally should be an intervening
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cerebellar vermis.
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Now, if we look closely at this axial T2 image,
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we do see a small rudimentary
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cerebellar vermis,
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so it's not completely absent.
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But for the most part,
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we have midline continuity between
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the two cerebellar hemispheres,
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likely midline continuity or at least close
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in the deep cerebellar gray matter.
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So, this is an entity called
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rhombencephalosynapsis.
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During development,
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the rhombencephalon is the hindbrain,
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and if we think synapse is...
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like, comes together.
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So, rhombencephalosynapsis means
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the rhombencephalon has come together,
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or in this case, actually, it never cleaved.
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It stayed together.
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So,
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if we look on this sagittal view,
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we see the cerebellar vermis,
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or what should be the vermis,
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doesn't have a normal foliation pattern for vermis.
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This actually looks like a cerebellar foliation
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pattern with the branching points
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and secondary branching points here.
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e're not seeing the normal primary and
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secondary fissures of the cerebellum.
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We're seeing something that looks more like a
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cerebellar hemisphere than a cerebellar vermis.
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Now, anteriorly and inferiorly,
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we do see this,
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which is the rudimentary cerebellar vermis.
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So, it's a little bit trickier to identify
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on this sagittal image.
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But on the coronal image,
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we can see midline continuity of the folia
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across both cerebellar hemispheres.
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And additionally,
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we see that in the axial T2-weighted image,
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where we have both the gray matter,
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white matter,
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and deep gray structures that come together.
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So, this is a case of rhombencephalosynapsis.
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