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5 fetal neurologic abnormalities to not miss

Deborah Levine, MD

BETH ISRAEL DEACONESS

MEDICAL CENTER

HARVARD

MEDICAL

SCHOOL

• I have no disclosures pertinent to this talk

1. First trimester anencephaly

2. Ventriculomegaly in its many forms

3. “Absent” cerebellum that is a Chiari malformation

4. Agenesis of the corpus callosum

5. Intracranial hemorrhage

First trimester anencephaly

Elevated aFP at 16 weeks

https://embryology.med.unsw.edu.au/embryology/index.php/Musculoskeletal_System_-_Skull_Development#Fetal_Head_Growth

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Anencephaly – 10 weeks

Ventriculomegaly in its many forms

Cerebral Ventricles

Atrium < 10 mm

Choroid fills ventricle

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Ventriculomegaly (VM)

• Enlargement of the fetal lateral ventricles >10 mm

Cavum Septi Pellucidi Transvaginal scan corpus callosum

Mild Ventriculomegaly

10% risk of chromosomal anomaly

Both of these fetuses had Trisomy 21

Causes of VM

• Obstruction

• Dysgenesis

• Destruction

• A combination of the above

• Sometimes we never know the etiology

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MRI Obstruction - Global dilatation effacement of sulci

Angular ventricles

Obstruction due to Chiari Malformation

100% specific for NTD! Levine, Radiology 2002

Causes of VM: Dysgenesis

• Aneuploidy • Abnormal brain growth or development

– Holoprosencephaly – ACC – Migrational abnormalities – Hemimegalencephaly

• Cerebral dysgenesis with microcephaly – Small head size – Sloping forehead indicating lack of

development of forebrain – Prominence of the extra-axial CSF spaces

Holoprosencephaly Dysgenesis: Fused frontal horns

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Hemimegalencephaly

35 weeks

• Loss of brain parenchyma –Hemorrhage –Vascular insult – Infection

Causes of VM: Destruction

DWM, VM, Porencephaly Hydranencephaly

“Absent” cerebellum that is a Chiari malformation

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Agenesis of the corpus callosum

Neuronal Migration Abnormality

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ACC and stenogyria

ACC and heterotopias

Intracranial hemorrhage

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Hemorrhage

Venous infarction Intratentorial Hematoma

My 5 things to not miss

• Anencephaly in first trimester – return in 1 week if unsure

#1

#2

• Ventriculomegaly in its many forms – look for associated findings – morphology is a clue!

#3

• If you don’t see the cerebelllum, think fruit!

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#4

• ACC – look for associated findings – they strongly affect prognosis

#5

• Hemorrhage can lead to porencepahly and ventriculomegaly – need to work up the fetus for bleeding diathesis and at times deliver by c-section