Interactive Transcript
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This is an MRI of a 13-month-old child with
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a known lumbosacral meningomyelocele.
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And we know that a lumbosacral meningomyelocele
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has essentially a 100% association with an
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intracranial Chiari type II malformation.
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So,
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this MRI, sagittal T1-weighted image, shows
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we see a vertically oriented,
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very small in caliber fourth ventricle.
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We see an abnormal appearance of the cerebellar
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vermis and cerebellar ectopia,
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which includes the cerebellar tonsils
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and the cerebellar vermis.
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We will confirm that on the axial images,
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you can see
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cerebellar tonsils and the cerebellar vermis
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extending down into an enlarged foramen magnum.
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We're seeing several other features.
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We're seeing a large massa intermedia.
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We're seeing somewhat of a beaked appearance or
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posteriorly pointing appearance of the tectal plate
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related to a more horizontal appearance
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and configuration of the inferior colliculi.
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Now,
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every patient with Chiari type II malformation
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is a little bit different.
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This patient,
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the corpus callosum, doesn't look too abnormal.
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We're seeing somewhat truncation of the
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rostrum of the corpus callosum,
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but the genu and the body of the
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corpus callosum are normal.
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We have the physiologic thinning of the isthmus,
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and we have the splenium of the corpus callosum.
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The corpus callosum may be slightly
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smaller than usual,
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but this is not as abnormal as we sometimes see.
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Here,
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we see what may be an interhypothalamic adhesion.
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This is a finding that has been seen slightly
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more commonly in the setting of a
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Chiari Type II malformation.
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Notice other adjacent structures.
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There's the massa intermedia.
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There is the anterior commissure,
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the optic chiasm.
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But this structure right here,
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just posterior to the lamina terminalis,
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might be an interhypothalamic adhesion.
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If we look on this Chiari type II malformation,
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we can see there's a ventriculoscopy catheter
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in place because there's a near 100% association
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of Chiari Type II malformation with hydrocephalus.
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Now, with the ventriculoscopy catheter in place,
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the ventricles are now normal in size,
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so it's doing its job.
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But we see another interesting finding that's
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characteristic of Chiari type II malformations.
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We see interdigitation of gyri
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across the interhemispheric fissure.
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This is felt to be related to fenestration
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of the falx cerebri.
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And in this case,
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you actually could even see this finding
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on this coronal head ultrasound
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at one month of life.
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So, we're seeing interdigitation of gyri in the
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setting of a Chiari Type II malformation with
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the characteristic posterior fossa and
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supratentorial abnormalities.
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