Abnormalities Of The Fetal Brain

1. Choroid Plexus Cyst 

        between 14-24 weeks gestation  

• Disappear by 28 weeks
• >3mm considered CPC

• Associated with Trisomy 18 (but must have other detectable abnormalities) 

2. Ventriculomegaly and Hydrocephalus

• Ventriculomegaly: large ventricles, head itself may be normal, large or even smaller than expected gestational age.
• Hydrocephalus: enlarged ventricles associated with increased intracranial
  pressure and thus causes head enlargement 
  
  
  

3. Acrania: Absence of cranial vault bones 

• Usually associated with echogenic amniotic fluid caused by debris shed from the uncovered brain or
• Other unprotected fetal parts

 

4. Holoprosencephaly

• Incomplete cleavage of prosencephalon  

 

• Associated with facial changes such as:

         1. Cyclopia with single eye (with or without proboscis)

         2. Ethmocephaly (hyoptelorism and proboscis between eyes)

         3. Median cleft lip/ palate and hypotelorism

5. Dandy-Walker Malformation

• Cystic dilation of 4^th ventricle
• Elevated tentorium
• Small, raised or absent vermis 

 

6. Microcephaly/ Micoencephaly

 

• Disproportionately small head for fetal age and body size
• Measured using BPD and HC

7. Absence of Corpus Callosum

• Mild Ventriculomegaly with thin anterior horns and pointing (colpocephaly)
• Ventricles are parallel
• Absent cavum septum pellucidum
• Third trimester mid-sagittal view shows radial orientation of sulci from the thalamus (sunburst appearance)