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Moderate Severity Dandy-walker Spectrum

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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.

Report

Description

Faculty

Asim F Choudhri, MD

Chief, Pediatric Neuroradiology

Le Bonheur Children's Hospital

Tags

Ultrasound

Pediatrics

Neuroradiology

MRI

Idiopathic

Congenital

Brain

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