ERU-24 The Fetal Head and Brain Flashcards
Neural plate > neural tube > procen-, mesen-, rhombencephalon
When does the posterior fontanelle close?
The anterior fontanelle?
by 6 months
by 18 months
What is the function of the falx cerebri?
The corpus callosum?
Separates the 2 cerebral hemispheres
Connects the 2 hemispheres
Absence of the cavum septum pellucidum would indicate what?
Agenesis of the corpus callosum, the part that connects the 2 cerebral hemispheres
What connects the 2 lobes of the thalamus?
The masa intermedia or interthalamic adhesion which passes through the midline of the 3rd ventricle
What lines the 4 ventricles of the brain?
Ependyma
1st and 2nd ventricle > foramen of Monroe > 3rd ventricle > aqueduct of Sylvius/cerebral aqueduct > 4th ventricle > foramen of Luschka to bathe brain or foramen of Magendie to the cysterna magna and subarachnoid space.
What is a cephalic index?
What does a CI of <75 indicate?
>85?
When estimating gestational age, what should you be used besides by parietal diameter in this instance?
A tool used to indicate the shape of the fetal head
Dolichocephalic/scaphocephaly (long, narrow)
Brachiocephalic (short and round)
Head circumference
What is a normal lateral ventricle measurement?
<10mm
- What condition(s) would be indicated by a Lemon head shape?
- Strawberry
- Cloverleaf
- Microcephaly
- Macrocephaly
- Brachycephaly
- Dolichocephaly
- Chiari II malformation
- Trisomy 18
- Thanatophoric dysplasia
- TORCH, Tris 13, Tris 18, Meckel-Gruber syndrome
- hydroceph, tumor, familial, beckwith-wiedemann
- Craniosynostosis, tris 21, tris 18
- Craniosynostosis
What is a normal cisterna magna measurement?
Larger would indicate what?
Smaller would indicate what?
2 - 10mm
larger: Dandy-Walker complex
smaller: Arnold-Chiari II malformation
What does the “dangling choroid sign” indicate?
Ventriculomegaly. Choroid plexus dangling and surrounded by CSF.
What is the most common cause of hydrocephalus in utero?
Aqueductal stenosis: normal 4 ventricle & all others dilated.
How is hydranencephaly be differentiated from alobar holoprosencephaly?
In holoprosencephaly, a rim of cerebral tissue is maintained.
In hydranencephaly, no cerebral mantle is present
A horseshoe shaped monoventricle in the fetal brain indicates what?
alobar holoprosencephaly
What diagnoses are associated with holoprosencephaly?
Tris 13 (Patau syndrome) present in 50-70% of cases
What are the sonographic findings of Dandy-Walker malformation?
Enlargement of cisterna magna (>10mm)
Communication of the enlarged CM with a dilated 4th ventricle
Agenesis or hypoplasia of the cerebellar vermis
Varying degrees of ventriculomegaly
How does DWS differ from mega cisterna magna, sonographically?
MCM will have normal cerebellum and 4th ventricle
What would be the pathomnemonic finding of agenesis of the corpus collosum on ultrasound?
The absence of the corpus collosum and cavum septum pellucidum after 18 weeks + “sunburst” or “spoke wheel” pattern.
What is the sonographic finding indicating schizencephaly?
Fluid-filled clefts within the cerebrum
Agenesis of CSP and corpus collosum
Ventriculomegaly
What is porencephaly?
A rare condition in which a cyst communicated with the ventricular system in the brain. Associated with stroke. Usually unilateral
How can porencephaly be distinguished from an arachnoid cyst?
Arachnoid cysts do not communicate with the brains ventricular system.
What is lissencephaly?
A condition distinguished by lack of gyri and sulci in the cerebrum.
TORCH infection
Toxoplasmosis Other Rubella Cytomegalovirus (most common) Herpes simplex
causes calcifications and ventriculomegaly
What is the most common fetal intracranial tumor?
Teratoma
What is a vein of Galen aneurysm associated with?
CHF in the newborn
fetal hydrops
The resistance pattern of the MCA should be (< / >) the umbilical artery.
An abnormality indicates what?
Greater than
MCA/UA : >1 = normal
Hypoxia, especially if FGR
What is Apert syndrome?
A genetic disorder that includes craniosynostosis, midline facial hypoplasia, and syndactyly
How is the cephalic index calculated?
CI = BPD/OFD * 100
OFD equals occipital frontal diameter
