Interactive Transcript
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This is the mid-sagittal
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transfontanelle ultrasound
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in a one day old child that
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had an abnormal fetal ultrasound.
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And on this,
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we see some normal structures.
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We see the corpus callosum,
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see the midbrain,
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the pons, the brainstem.
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This is the cerebellar vermis.
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But inferiorly,
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we don't see the rest of the cerebellar vermis.
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We see be something right here,
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but it's not connected to the remainder
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of the cerebellar vermis.
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One tool that we have more recently in
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evaluating the posterior cranial fossa
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on neonatal head ultrasounds,
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is this a transfontanelle view?
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In this transfontanelle view,
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this is somewhat of a sideways appearance.
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This is one cerebellar hemisphere.
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This is the other cerebellar hemisphere,
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and there's a separation between them.
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This is the fourth ventricle.
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So, we start to have what
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looks like a hypoplastic cerebellar vermis,
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and one of the ways
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to better characterize that is on MRI.
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An MRI was performed at approximately
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one year of life,
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and if we were looking at the posterior fossa,
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we can see the fourth ventricle posteriorly
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connects to this CSF space here,
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and there's some separation of
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the cerebellar hemispheres,
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and there's a hypoplastic cerebellar vermis.
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If we look at the mid sagittal
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T-1 weighted image,
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we see the superior aspect
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of the cerebellar vermis looks normal.
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But inferiorly, it's missing.
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This here is actually,
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we can see on this axial image,
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is portions of the cerebellar hemisphere
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protruding into the midline
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because there's no vermis
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to take its place and push it to the side.
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So, there's some cystic prominence of the
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posterior cranial fossa in continuity with the
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fourth ventricle and hypoplastic
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cerebellar vermis.
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Now, this is considered to be
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in the Dandy Walker spectrum of malformations.
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This is not a classic Dandy Walker malformation,
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where the poster fossa is markedly dilated,
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where there is more severe hypoplasia
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of the cerebellar vermis and more uplifting
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of the cerebellar vermis.
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So, this is a moderate severity Dandy Walker
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spectrum malformation.
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In the past,
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people referred to these as Dandy Walker variant,
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but the term Dandy Walker variant,
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to me is not appropriately descriptive.
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It doesn't tell you how severe something is.
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Dandy Walker variant could, to some people,
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mean that 10% of the vermis
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is missing or 50% or 90%
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Well, I think this one,
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approximately 50% of the cerebral vermis
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is missing.
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So to me,
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this would be a moderate severity
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Dandy Walker spectrum malformation.
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Now, additionally, we can see,
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this is the location of the nuchal ligament insertion.
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Here is the torcula.
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So, the torcula is slightly elevated from
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the insertion of the nuchal ligament.
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So, there is some enlargement of the
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posterior cranial fossa,
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but it is nowhere near as severe as in the
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classic Dandy Walker malformations.
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