Interactive Transcript
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This is a fetal ultrasound performed
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at 29 weeks gestation,
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and it shows profound ventriculomegaly.
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We can actually see dangling choroid plexus.
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And this was further characterized with fetal MR.
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That fetal MR shows massive enlargement of
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both lateral ventricles.
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We scroll inferiorly.
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The third ventricle is on the bigger side.
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The fourth ventricle is not enlarged.
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If we look at this sagittal image,
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we see the massive enlargement
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of the lateral ventricles.
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There's enlargement of the third ventricle.
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And if I zoom in,
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I can actually see the superior aspect of
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the aqueduct of sylvius looks patent.
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We're not seeing it inferiorly.
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And while this is a very small structure,
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the fact that we have a tri ventricularmegaly,
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both lateral ventricles and the third ventricle
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without an abnormality of the fourth ventricle,
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or at least without enlargement
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of the fourth ventricle,
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suggests that the aqueduct of Sylvius is a likely
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location for an abnormality of CSF flow.
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Now, there's another finding that we see.
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The cerebellar vermis has an unusual configuration,
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including an abnormal configuration of
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the nondilated fourth ventricle.
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If we look on this image,
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we're actually in axial image of the posterior fossa.
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We're not seeing a cerebellar vermis,
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and we're seeing sort of a rounded appearance
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of the posterior aspect of the cerebellum.
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That, to me,
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is suggestive of rhombencephalosynapsis.
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Obviously,
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we want to confirm this with postnatal imaging,
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but this is suggestive of rhombencephalosynapsis.
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And why does this make sense?
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Well,
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rhombencephalosynapsis can be associated with
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a congenital aqueductal stenosis.
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That congenital aqueductal stenosis is felt to be
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related to abnormal transverse migration
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of the inferior colliculi,
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resulting in something that could be
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referred to as mesencephalon synapses.
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So in patients with aqueductal stenosis,
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always pay attention to the cerebellar vermis,
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and you may actually find that there's also
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associated rhombocephalus synapses.
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That may then
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allow appropriate referral to genetics for
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evaluation of other genetic abnormalities.
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