12th World Congress in Fetal Medicine · Dandy Walker malformation Normal Normal vermis Megacisterna Magna Asymmetry cerebellar hemispheres Normal vermis Arachnoid cyst Absence/Small

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Posterior fossa defects

Magda Sanz-Cortes

Maternal Fetal Medicine Research Group Hospital Clinic-University of Barcelona, Spain

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12th World Congress in Fetal Medicine

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Cerebellar hypoplasia

Romboencepahlosynapsis

Obliteration of the PF

Increased PF

Fetal Posterior fossa pathology Abnormal PF

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Examination

CEREBELLUM

POSTERIOR

FOSSA

CSP

SYMMETRIC

Axial plane: Transcerebellar

Measurements

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Examination

Axial plane: Transcerebellar

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Examination

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Structures

TENTORIUM

CEREBELLUM

MEDULLA

PONS CISTERNA

MAGNA

4th VENTRICLE

Posterior fossa

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Abnormal PF

If PF >10mm

Differential diagnosis:

MEGACISTERNA MAGNA

PF ARACHNOID CYST

BLAKE´S POUCH CYST

DANDY WALKER

MALFORMATION

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Abnormal PF MEGACISTERNA MAGNA

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Abnormal PF

Coronal plane Sagital plane

If isolated: Good prognosis

- PF>10mm

- Normal vermis

- Normoinserted tentorium

MEGACISTERNA MAGNA

Dror J Child Neurol 2009Bolduc Dev Med Child Neurol 2010; Long Prenat Diagn 2006

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Abnormal PF

PF ARACHNOID CYST

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Coronal plane

Abnormal PF

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Coronal plane Sagital plane

Abnormal PF

If isolated: Good prognosis

- PF>10mm

- Asymmetry

- Normal vermis

- Normal 4th ventricle

- Tentorium could be displaced

PF ARACHNOID CYST

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Abnormal PF BLAKE´S POUCH CYST

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Abnormal PF

If isolated: Good prognosis

Coronal plane Sagital plane

- 4th ventricle and PF communicated

- Normal vermis

- +/- Normoinserted tentorium

BLAKE´S POUCH CYST

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Abnormal PF DANDY WALKER MALFORMATION

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Abnormal PF DANDY WALKER MALFORMATION

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Coronal plane Sagital plane

Abnormal PF

Adverse prognosis

Rule out associated malformations

- PF>10mm

- Absence/Hypoplasic vermis

- Displaced tentorium

DANDY WALKER MALFORMATION

Long Prenat Diagn 2006

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Vermis

Normal

Tentorium

Suggestive US sign

Megacisterna

Magna

Nr

+

Isolated increased PF

PF arachnoid

cyst

Nr

+/-

Asymmetry

Blake´spouch

cyst

Nr

+/-

Hourglass sign

DWM

Absent/hypoplastic

-

Absent/hypoplasic

vermis

Abnormal PF If PF >10mm

Sonographic signs

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• If PF is > 10mm: Neurosonography for TV coronal and sagital planes.

Axial plane

Hourglass sign

Normal

vermis

Blake´s

pouch cyst Dandy Walker

malformation

Normal

Normal

vermis

Megacisterna

Magna

Asymmetry

cerebellar

hemispheres

Normal

vermis

Arachnoid

cyst

Absence/Small

vermis

Hypoplastic/

Absent vermis

Conclusions

Good prognosis Adverse prognosis

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Thank you !

msanz1@clinic.ub.es

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Examination Sagital plane: Transcerebellar

Measurements