head/brain Flashcards
what dies MSAFP stand for?
maternal serum alpha-fetoprotein
greater than 2.5 standard deviations from the median is abnormal & suggests what?
an open neural tube defect (NTD)
an increased fundal height raises suspicion for?
polyhydramnios
what is associated with a lemon shaped head?
spina bifida
a strawberry shaped head is associated with what?
trisomy 18
brachiocephy is a rounded head shape
true/false
true
what is brachiocephaly associated with?
chromosomal abnormalities
genetic syndromes
dolicocephaly is generally due to head molding in the vertex position
true/false
false; breech position
what is ventriculomegaly?
ventricular enlargement characterized by excessive CSF w/in cerebral centricles
what are some things that can cause ventriculomegaly?
obstruction to outflow (hydrocephalus)
decreased CSF absorption
overproduction of CSF
what is hydrocephalus?
term for ventricular enlargement secondary to increased intracranial pressure &/or head enlargement
the atrium of the lat vents shoukd not exceed:
10 mm
what is the most common type of intraventricular obstruction?
aqueductal obstruction (stenosis)
what are the other types of intraventricular obstructions?
chiari II malformation
dandy walker malformation
what is a cause for extraventricular obstruction?
arachnoid cyst
what are some additional anamalies that may be present with ventriculomegaly?
spina bifida dandy walker syndrome encephalocele cardiac malformations renal malformations abnormal karyotypes
what is the sonographic appearance of ventriculomegaly?
excess fluid in lateral & 3rd vents
atrium greater than 10mm
choroid plexus may dangle w/in CSF
what are some other associated so ographic findings of ventriculomegaly?
polyhydramnios
abnormal fetal lie
hepatomegaly & fetal ascites
meningomyelocele
what may be present with anencephaly?
portions of the midnrain & brain stem
what are some other features of anencephaly?
buldging eyes
macroglossia
very short neck
AFP will be elevated
with anencephaly, the face & orbits will be present, giving the face what type of appearance?
frog-like
what are some other sonographic findings associated with anencephaly?
- major portions of cranium & intracranial strctures are absent
- polyhydramnios
- talipes (club foot) also a common finding
can be diagnosed as early as 12wks
a bony defect in the skull allows herniation of intracranial contents. what are those types of herniations called?
cranial meningocele
encephalocele
encephalocele contains only meninges & CSF
true/false
false; contents inclue brain & CSF
what is the most common site for a herniation of the skull? what are the other sites?
occipital
frontal
parietal
what could cause an encephalocele?
amniotic bands
what is the sonograhic appearance of an encephalocele?
may be cystic near the cranium
brain tissue may be present w/in the mass
what is holoprosencephaly?
incomplete cleavage or diverticulation of primitive forebrain into 2 hemispheres
what is holoprosencephaly strongly associated with?
trisomy 13
what are the 3 classifications of holoprosencephaly?
alobar
semilobar
lobar
which is the most severe form of holoprosencephaly?
a. semilobar
b. a bar
c. lobar
d. alobar
d. a lobar
* lacking 2 hemispheres*
what brain structures are absent with alobar?
falx
corpus callosum
cavum septum
what are the facial abnormalities associated with alobar?
hypotelorism
cyclopia
midline facial clefts
semilobar resembles lobar
true/false
false; it resembles alobar
what facial abnormality is associated with semilobar?
cleft lip/palate
what is the least severe form of holoprosencephaly?
a. alobar
b. the bar
c. lobar
d. semilobar
c. lobar
* 2 hemispheres are present*
what is dandy-walker complex?
congenital malformation of the posterior fossa, specifically the cerebellar vermis
what is dandy-walker malformation?
small or absent cerebellar vermis
cisterna magna enlargement
which of the following is a variant of dandy-walker?
a. arnold-walker
b. vermian hypoplasia
c. dandy hyperplasia
d. vermian hyperplasia
b. vermian hypoplasia
why is it not possible to diagnose vermian hypoplasia until after 18wks?
vermis not developed until 18wks
what are other associations of dandy-walker?
ventriculomegaly
agenesis of corpus callosum
spina bifida
microcephaly
what is the sonographic appearance of dandy-walker?
- complete or partial agenesis of the cerebellar vermis
* cisterna magna enlargement (>10mm)
what is arnold chiari type II malfirmation?
displacement of cerebellar vermis, 4th ventricle, & medulla oblongata through the foramen magnum into the upper cervixal canal
what is arnold chiari II frequently associated with?
spinal dysraphia
cerebellum will be compressed against the back of the cranium demonstrating what sign?
banana sign
what is microcephaly?
small head circumference measuring more than 3 standard deviations below the normal
what is associated with microcephaly?
intrauterine infections
aneuploidy/syndromes
underlying CNS anomaly
what is the sonographic appearance of microcephaly?
small BPD decreased HC/AC ratio poor cranial growth in serial scans no definitive nasal/forhead differentiation high false positive rate
the corpus callosum is the smalles neural tract connecting the cerebral hemispheres
true/false
false; it’s the largest
what is agenesis of the corpus callosum (ACC)?
the failure of the development of the corpus callosum that may be partial or complete
what other abnormalities are commonly associated with ACC?
trisomies (especially 18 & 13) holoprosencephaly median facial clefts dandy-walker other syndromes or CNS anomalies (schizencephaly or lissencephaly)
what are some clinical associations of ACC?
isolated ACC may be asymptomatic
low intelligence
seizures
poor motor coordination
what is the sonographic appearance of ACC?
- disproportionate enlargement of occipital horns (colpocephaly)
- lateral displacement of both medial & lateral ventricular walls
- widely separated lateral ventricular frintal horns
- ventricles may demonstrate teardrop shape
- absence of cavum septum pellucidi
the vein of galen aneurysm is a true aneurysm
true/false
false
what is hydranencephaly?
destructive process causing total or near total absence of cerebrum
it is the most severe degree of porencephaly or brain destruction
what is the MOST common cause of hydranencephaly?
occlusion of the carotid arteries in the first or early second trimester
what is the sonograohic appearance of hydranencephaly?
- head size commonly normal but can be small or large
- falx is present but may be displaced or hypoplastic
- variable presence of 3rd vent
- may be difficult to distinguish from a severe hydrocephaly
what destructive process crates a cleft in the cerebral cortex?
a. hydrancephaly
b. lissencephaly
c. spina bifida
d. schizencephaly
d. schizencephaly
what is the sonographic appearance of schizencephaly?
fluid-filled clefts in the cerebral cortex that can be uni/bi lat
what is associated with schizencephaly?
midline brain defects
ventriculomegaly
septic optic dysplasia
agenesis or dysgenesis or the corpus callosum
absence of septum pellucidum
heterotopias (displacement of gray matter)
polymicrogyria (many folds on surface of brain)
lissencephaly has a smooth brain surface with normal sulci & gyri
true/false
false; it does not have sulci & gyri
when is lissencephaly usually diagnosed?
third trimester
what is associated with lissencephaly?
agenesis of corpus callosum
dandy-walker
colpocephaly
what are porencephalic cysts?
cysts filled with CSF that communicate w/ the ventricular system
are choroid plexus cysts malignant or benign?
benign
