Abnormal Brain

What is ventriculomegaly/hydrocephalus?

enlargement of the vetricles

What is the most common brain abnormality?

ventriculomegaly/hydrocephalus

How does ventriculomegaly/hydrocephalus appear on ultrasound?

• >10 mm at atrium

• dangling choroid sign

• severe cases—>look for rim of cerebral tissue

What is the most common cause of hydrocephalus?

aqueductal stenosis

What is aqueductal stenosis?

narrowing of cerebral aqueduct that causes dilatation of 3rd ventricle and lateral ventricle

What is hydranencephaly?

• cerebral tissue is replaced by fluid—no cerebral hemispheres, only brain stem/basal ganglia present

• no rim of cerebral tissue seen within cranium like there is with severe hydrocephalus

What is holoprosencephaly?

• varying degrees of absence of midline structures and fusion of non-midline brain structures starting anteriorly

• associated with midline facial defects

• 3 degrees of severity—lobar, semilobar, alobar

What condition is holoprosencephaly strongly associated with?

T13 (Patau syndrome)

What is lobar holoprosencephaly?

• most mild form—minimal fusion

• absent CSP/CC

• fused frontal horns—heart shaped

• the rest is intact

What is semilobar holoprosencephaly?

• partial fusion of lateral ventricles and thalami, partial falx, absent CSP/CC

• butterfly shaped lateral ventricles

What is alobar holoprosencephaly?

• most severe form

• no midline separation of hemispheres

• midline brain structures are absent and non-midline are fused

• horse-shoe shaped monoventricle, fused thalami

• fatal

What facial defects are associated with holoprosencephaly?

• cyclopia (one eye)

• anophthalmia (no eyes)

• hypotelorism (closely spaced eyes)

• median cleft lip

• cebocephaly (1 nostril and hypotelorism)

• ethmocephaly (no nose, proboscis, hypotelorism)

What is Dandy-Walker malformation?

• absence or defect of the cerebellar vermis causing 4th ventricle to dilate and cisterna magna to enlarge

• splayed cerebellar lobes—keyhole appearance

What is the vein of Galen aneurysm?

• arteriovenous malformation—>abnormal connection between artery and vein

• anechoic tubular mass midline brain with turbulent color flow patterns

What is vein of Galen aneurysm associated with?

hydrops

How does agenesis of the corpus callosum appear on ultrasound?

• absence of CSP

• colpocephaly (splayed and teardrop shaped lateral ventricles)

• sunburst/radial pattern sulci

What is a choroid plexus cyst?

• frequently encountered on routine sono

• usually regress by 3rd trimester

• if isolated—>normal fetus

What is a choroid plexus cyst a soft marker for?

T18 (Edwards syndrome)

What findings are associated with T21?

septal defects/EIF

What finding is related to T13?

holoprosencephaly

What finding is related to T18?

choroid plexus cysts

What is schizencephaly?

fluid-filled clefts within cerebrum

What is porencephaly?

cyst that communicates with ventricular system caused by hemorrhage, ischemia, or vascular occlusion

What is lissencephaly?

• smooth brain

• no sulci/gyri within cortex (agyria)

• only diagnosed in 3rd trimester

What is a teratoma?

most common intracranial tumor; same appearance as other teratomas