Ch. 60 Test Flashcards
_______ is a condition in which there is complete or partial absence of the cranial bones with brain tissue present
acrania
______ is a form of holoprosencephaly characterized by a single ventricle, hypotelorism, and a nose with a single nostril
cebocephaly
______ is an open spinal defect with protrusion of the meninges
meningocele
______ is an elargment of the fetal head
macrocephaly
A _______ is a congenital malformation or abnormality
anomaly
______ is a congenital absence of the cerebral hemispheres due to an occlusion of the internal carotid arteries
hydranecephaly
______ is a neural tube defect in which the cranium, cereberum and cerebellar hemispheres are absent
anencephaly
A _____ is a malformed cylindrical nose
proboscis
_____ is an open spinal defect characterized by protrusion of meninges and spinal cord through the defect
meningomyelocele
________ is a failure of the dorsal arches of the spinal vertebrae to fuse
spina bifida
After the 1st trimester, the spinal cord grows at a _____ rate than the vertebral column
slower
Neural function begins at _____ weeks gestation
6
The fetus has defined periods of activity and rest by the end of the ____ month of pregnancy
4
The fetus normally displays the sucking reflex by ____ months gestation
6
Many congenital malformations of the central nervous system are the result of
incomplete closure of the neural tube
_____ it the most common neural tube defect
anencephaly
Angiomatous stroma or cerebrovasculosa is the
thick membrane covering the remnant brain in anencephalic infants
_____ of anencephalic infants die before birth
50%
A lack of dietary ____ is associated with increased risk of neural tube defects
folic acud
Excessive consumption of _____ is associated with increased risk of neural tube defects
zinc
What are the sonographic findings with anencephaly
absence of brain/cranial vault, rudimentary brain tissue, bulging fetal orbits, frog eyes, no cranium, theater mask face
_____ occurs when mesenchymal tissue does not migrate to form bone over cerebral tissue
acrania
Presence of brain tissue without overlying cranium, disorganization of brain tissue and prominent sulcal markings are all sonographic findings of
acrania
Encephalocele and cranial meningocele are both examples of
cephalocele
______ is a herniation of meninges and brain through a defect in the cranium
encephalocele
_____ is a herniation of only meninges through a defect in the cranium
cranial meningocele
Why are cranial neural tube defects associated with polyhydramnios
decreased swallowing
What are the sonographic findings of cephalocele
extracranial mass, bony skull defect, ventriculomegaly
Cephaloceles that occur away from the midline of the fetal head are usually the result of
amniotic band syndrome
Describe spina bifida occulta
least severe, no rooftops, skin intact
Describe spina bifida cystica
cystic sac, increased MSAFP, splaying (U or V), meninges/spinal cord protrude
A large, open spina bifida lesion is called
rachischisis
Describe the characteristics of arnold chiari II malformation
banana and lemon sign, no cistern magna, displacement of cerebellar vermis
Describe the banana sign
cerebellum banana shaped because its pulled into foramen magnum
Describe the lemon sign
scalloping of frontal bones inward 2 degrees to posterior disp of brain, frontal bossing
The higher the lesion with spina bifida, the ____ the prognosis
worse
The larger the lesion with spina bifida, the ____ the prognosis
worse
Describe the sonographic appearance of spina bifida
splaying of posterior ossification centers (U or V), protrusion of sac like structure, cleft in skin
Cranial findings associated with spina bifida include
ventriculomegaly, banana and lemon sign
The lemon head sign is specific for spina bifida
false
_____ is a defect resulting from the agenesis or hypoplasia of the cerebellar vermis causing dilation of the 4th ventricle in the brain
dandy walker malformation
Describe the sonographic features of holoprosencephaly
no midline falx, c shaped ventricle, fused thalamus, dorsal sac, absent CC/CSP, hypotelorism
Describe the sonographic features of dandy walker malformation
posterior fossa cyst, splaying cerebellar hemispheres, enlarged cistern magna, ventriculomegaly, polyhydramnios
Describe alobar holoprosencephaly
most severe, single ventricle, horseshoe shaped, fused thalamus, absent IHE/CSP/CC/optic tracts/olfactory bulbs/falx
Describe semilobar holoprosencephaly
almost complete division of ventricles, rudimentary midline falx, partial occipital horns, partial/complete fused thalamus, absent CC/CSP/olfactory bulbs
Describe lobar holoprosencephaly
least severe, complete division ventricles, absent CSP/CC/olfactory bulbs, fused thalamus
Which chromosomal anomaly is holoprosencephaly most closely associated with
trisomy 13
What teratogens are associated with holoprosencephaly
alcohol, phenytoin, retenoic acid, maternal diabetes, congenital infection
What facial anomalies are associated with holoprosencephaly
cyclopia, hypotelorism, absent nose, flat nose with single nostril, proboscis
The _____ is a fibrous tract connecting the cerebral hemispheres
corpus callosum
Agenesis of the corpus callosum is associated with
abnormal lateral ventricle, dilation of the 3rd ventricle, absence of the CSP
_____ results from obstruction, atresia or narrowing of the cerebral aqueduct, causing dilation of the ventricles
aqueductal stenosis
_____ is associated with CMV, reubella, and toxoplasmosis infections
aqueductal stenosis
____ is an infection pregnant women get when they change the litterbox of their cats
toxoplasmosis
____ aqueductal stenosis is associated with profound mental retardation and abnormal flexion of the thumb
x-linked
The _____ is located under the cerebral hemispheres and drains blood from the anterior and central brain into the venous sinuses of the posterior fossa
vein of galen
____ is a direct connection between an artery in the brain and the vein of galen
vein of galen aneurysm
AV malformation of vein of galen causes hemodynamic changes that result in
cardiac overload and NIH
A _______ is seen sonographically as a cystic space midline and superior to the 3rd ventricle in the fetal brain. It demonstrates turbulent flow in doppler
vein of galen aneurysm
In most cases, fetuses with choroid plexus cysts will be
normal
A ____ is a cyst within the brain parenchyma which is the result of hemorrhage, infarction or inflammation
porencephalic cyst
____ means divided brain
schizencephaly
_____ is characterized by clefts in the cerebral cortex. It is thought to be a result of abnormal migration of neurons
schizencephaly
Patients with schizencephaly may exhibit
seizures, microcephaly, hydrocephaly
In cases of hydrancephaly, brain tissue
is normal at first, then later destroyed
Which of the following can cause hydrancephaly
maternal hypotension, infections like toxoplasmosis or CMV, agenesis of the ICAs
Explain the difference between ventriculomegaly and hydrocephalus
ventriculomegaly is enlargement of ventricles within the brain. Hydrocephalus is enlargement of head and compression of brain tissue from CSF buildup
Ventriculomegaly caused by aqueductal stenosis or other defect of the cerebral ventricles is
non communicating hydrocephalus
Ventriculomegaly caused by obstruction outside the ventricular system is
communicating hydrocephalus
____ can cause hydrocephalus by causing an over production of CSF
choroid plexus papilloma
Hydrocephalus is always associated with chromosomal abnormalities
false
Ventriculomegaly usually begins in the
occipital horns of the lateral ventricle
Describe the sonographic appearance of ventriculomegaly
lateral ventricular enlargement >10mm, dangling choroid sign, dilation 3rd/4th ventricles, fetal head enlargement
A cerebral ventricle is considered dilated when its AP diameter exceeds
10mm
_____ is an abnormally small head that measures 2 standard deviations below average
microcephaly
Most children with microcephaly are of normal intelligence
false
