Chapter 24-
what are the types of holoprosencephaly
1. alobar 2. lobar 3. semilobar
what are the main subtypes that are related to acrania?
1. anencephaly 2. exenephaly
what two structures dilate with DWM?
1. cisterna magna 2. fourth ventricle
what is absent with alobar?
1. corpus callosum 2. CSP 3. third ventricle 4. inter hemispheric fissure 5. falx cerebri
US findings of a teratoma
1. distorted brain structure 2. macrocephaly 3. calcifications
US signs of holo?
1. mono ventricle 2. fused loves of thalamus
at which week is the corpus callosum formed?
18w
what are newborns with vein of galen aneurysm prone to?
CHF
if the corpus callosum is absent, what else may be missing?
CSP
what is the most accurate fetal measurement at estimating gestational age?
HC
which syndrome is associated with cephalocele?
Meckel- Gruber syndrome
what will a corpus callosum lipoma appear as?
a solid, echogenic mass
definitive sign of DWM?
absent cerebellar vermis and enlarged fourth ventricle
what may hydranencephaly be confused with?
alobar holoprosencephaly hydrocephalus
the third ventricle communicates with the fourth ventricle via
aqueduct of sylvius
what can be confused with porencephaly?
arachnoid cysts
which neural tube defect is associated with cranial abnormalities and spina bifida?
arnold-chiari 2 malformation
where is the cerebral aqueduct located
between the third and fourth ventricle
what may be a cause of hydranencephaly?
bilateral occlusion of the internal carotids with destruction of the cerebral hemispheres 2. cytomegalovirus and toxoplasmosis
what US findings are consistent with intrauterine TORCH infections?
calcifications around ventricles and ventriculomegaly
what causes DWM?
caused by developmental abnormality in the roof of the fourth ventricle
what is a protrusion of intracranial contents through a skull defect?
cephalocele
which frequently encountered finding results in an increased risk of trisomy 18?
choroid plexus cyst
which intracranial tumor will produce an increase in the production of CSF?
choroid plexus papillomas
what is the term for small frontal horns and enlarged occipital horns/
colpocephaly
external signs of holo?
cyclopia 2. proboscis 3. anopthalmia 4. hypotelorism 5. median cleft lip 6. cebocephaly
what condition may occur if intracranial hemorrhage occurs within the parenchyma of the brain?
cystic cavities may form that communicate with the ventricular system leading to porencephaly
what is the most common in utero infection?
cytomegalobirus
agenesis or hypoplasia of the cerebellar vermis results in what cerebral malformation?
dandy-walker malformation
why do an MCA study?
effective evaluation of hypoxia
sonographic findings of DWM?
enlarged cisterna magna that communicates with a distended fourth ventricle cerebellar vermis is absent tentorium separates the cerebrum from the cerebellum and is elevated
what is present/absent with hydranencephaly
falx: absent present: brain stem and basal ganglia
what are the brain and skull changes with spina bifida?
flattened frontal bones (lemon sign) cerebellum displaced inferiorly and posteriorly (banana sign) cisterna magna obliterated lateral vents distorted small frontal horns and enlarged occipital horns
what is the sonographic appearance of anencephaly?
frog like faces, bulging eyes, absence of cranial vault
where is an intracranial hemorrhage usually originating?
germinal matrix (intraventricular hemorrhage)
what is a midline brain anomaly associated with brain aberrations and atypical facial structures?
holoprosencephaly
what is a fatal condition in which the entire cerebrum is replaced by a large sac containing CSF
hydranencephaly
what are the sonographic findings of a vein of galen aneurysm?
large anechoic mass within the midline of the cranium that has a turbulent venous/arterial flow when dopplered
what is a condition in which there are no gyro within the cerebral cortex?
lissencephaly
what is the most common location of spina bifida?
lumbosacral region
what is the most common risk factor for fetal intrauterine intracranial hemorrhage?
maternal platelet disorders
DWM may be confused with?
mega cisterna magna
is the cerebellum is normal and the fourth ventricle is not enlarged, what disease may be suspected?
mega cisterna magna
aqueduct stenosis
most common cause of hydrocephalus in utero
what is anencephaly?
no cerebral hemispheres present
what is exencephaly?
normal amount of cerebral tissue without the skull
most common location for a cephalocele?
occipital region
in which condition will a cyst communicate with the ventricular system?
porencephaly
DWM affects which area of the brain?
posterior fossa
pathology of intracranial hemorrhage?
ruptured thin vessels of germinal matrix hemorrhage spreads to lateral ventricle may lead to noncommunicating hydrocephalus
where is the germinal matrix located?
subependymal layer of ventricles
what is the typical appearance of absent corpus callosum?
sunburst appearance of sulci colpocephaly (small fontal horns and enlarged occipital horns) dilated third ventricle
what is a common intracranial tumor?
teratoma
what is acrania?
the absence of the cranial vault above the bony orbits
what does torch screen for?
toxoplasmosis other infections rubella cytomegalovirus herpes
what other chromosomal abnormality is present with holoprosencephaly?
trisomy 13 (Patau)
a choroid plexus cyst could be associated with increased risk of
trisomy 18
what is an av malformation that occurs within the fetal brain?
vein of galen aneurysm
dangling choroid sign is synonymous with?
ventriculomegaly
what are the common criteria for an infant with an intracranial hemorrhage?
weight is less than 1500 g born prematurely (<32 weeks(
distinctive factor between hydranencephaly vs. hydro/ holoprosencephaly?
with hydrocephalus and holoprosencephaly there is a rim of cerebral tissue maintained
which aspects of a fetus produces AFP?
yolk sac, getal gastrointestinal tract, fetal liver