Fetal Head Abnormalities Flashcards
Embryonic brain and spinal cord develop from
neural tube
Neural tube defects may either be
open or closed
Open NTD show an increase in what
maternal serum AFP and amniotic fluid AFP
What is macrocephaly?
larger than expected head size
What is the purpose of scanning for macrocephaly?
exclude intracranial abnormalities–hydrocephalus, intracranial tumor or macrosomia
What is microcephaly?
smaller than expected head
What is an intact calvarium?
calvarium is top part of skull
distinguishes microcephaly from anencephaly and encephacele
What’s the most common etiology of microcephaly?(3)
Fetal infection
Anoxia
Chromosomal abnormalities
What are the key sonographic features of microcephaly?
abnormal small head size (BPD or HC 2-3 SD below mean)
abnormal fetal biometric ratio (3 or more SD)
What is brachycephaly
head is rounder than usual
What is dolichocephaly
narrow BPD and low occipitofrontal diameter (OFD)
What causes brachycephaly? What causes dolichocephaly?
B- multiple gestations
D- Breech position/oligohydraminos
Lemon sign is associated with?
spina bifida
Clover leaf skull is associated with?
thanatophoric dysplasia, homozygous achondroplasia***
Strawberry shaped skull is associated with?
trisomy 18**
similar to lemon but no obvious concavity to the frontal bones
What is Spalding’s sign associated with?
fetal demise
What is Spalding’s sign
flattened and misshapen fetal head with overlapping cranial bones
fetal death is 4-7 days before overlapping/separation occurs
What measurement is considered scalp edema?
> 3mm
normal is under 3mm
Where do choroid plexus cysts arise from?
neuroepithelial folds in the choroid plexus
Where’s the most common site of choroid plexus cysts?
arterial region of lateral ventricle
Are choroid plexus cysts unilateral or bilateral
unilateral
When do we mostly see choroid plexus cysts?
16-24wks gestation
Do choroid plexus cysts persist or regress?
Regress
What are choroid plexus cysts associated with?
Tri18
Tri21
What are the key sonographic features we will see with agenesis of the corpus callosum?
absence of cavum septum pellucidum
colpocephaly (disproportion of occipital horns and lat ventricles)
What is agenesis of the CC associated with?
Dandy Walker Malformation (DWM)
Presence of _____ excludes ACC
CSP
What are the signs we we see with ACC? In sag, trv and cor
agenesis of corpus callosum
sunburst appearance (sag)
bullet shaped ventricles (ax)
bat wing appearance (cor)
ICC (intracranial calcifications) is the most common result of what
cytomegalovirus (CMV)
What are intracranial calcifications associated with
brain tumor such as teratoma
What is a complication of brain tumors (ICC)
hydrocephalus
What is the most common ICC
teratoma
Are teratoma’s benign or malig
also what do they look like
benign but can turn malignant
wide variety of tissue types and can resemble a hemorrhage
What is the vein of Galen/straight sinus
major draining vein that lies in the trv fissure within the subarachnoid space–posterior and slightly superior to thalami
What is a pathognomonic sign
a particular sign whose presence means that a particular disease is beyond any doubt
What is a vein of Galen aneursym
appears as a fusiform median cyst in the region of the trv fissure
Turbulent flow–high v, low z
What is acrania
absence of normal cranial vault with a normal appearing or disorganized brain above the orbits
What is anencephaly
absence of cranial vault, cerebral hemispheres and diencephalic structures
What is there an absence of with anencephaly
normally formed skin, cranial bones and brain superior to the orbits
Do bbs with anencephaly have a face?
yes, and eyes
What is the most reliable sonographic feature of anencephaly?
failure to identify normal cranial morphology and brain tissue above the orbits
What is a cephalocele
herniation of intracranial structures through a defect in cranium
If the cephalocele only contains meninges and CSF, what is it called
meningocele
If the cephalocele also contains brain tissue, what it is called? (2 names)
encephalocele or meningocephalocele
Is ventriculomegaly bilateral or unilateral
Bi
and symmetrical
What’s the best indicator of ventriculomegaly?
Atrial measurement
What is hydrocephalus/hydrocephaly
ventriculomegaly w/ increased intracranial pressure
What typically causes hydrocephalus/hydrocephaly
lesion causing obstruction of the CSF
