Chapter 23: Sonographic Assessment of the Fetal Head Flashcards
congenital absence of one or both eyes
anophthalmia
short broad head because of premature suture fusion
brachycephaly
congenital anomalies of the head caused by teratogens or development disruptions of the nervous system
cebocephaly
congenital brain anomaly resulting from a migrational defect of the occipital horns of the lateral ventricles leading to ventricular enlargement
colpocephaly
long narrow head
doliocephaly
abnormally formed organs
dysgenesis
malformation of an organ or structure
dysmorphic
dilatation or distention of a hollow structure
ectasia
nostrils
nares
either the rostral or caudal end of the neural tube
neuropore
graph
nomogram
disease characteristic
pathognomonic
posterior displacement of the maxilla and mandible
retrognathia
toward the cephalic or head end
rostral
substance that interferes with embryonic development
teratogen
central portion of the cerebellum between the hemispheres
vermis
axial biparietal diameter of brain
thalami
third ventricle
cavum septum pellucidi
axial cerebellum
cerebellum
cisterna magna
vermis
axial ventricles
ventricles
choroid plexus
coronal face
soft tissues of the nose, lips, chiin
sagittal profile
confirm correct symmetry of forehead, nose, lips, chin
Sonographic features of cleft lip/palate in axial view
linear defect through the maxilla/lip
Sonographic features of cleft lip/palate in coronal view
linear defect from nose to oral rim
abnormally shaped cephalic pole
absent neural tissue
loss of normal head contour
froglike eye appearance
spinal defects
omphalocele
clubfoot
cleft lip/palate
polyhydramnios
Sonographic features of meroanencephaly
single ventricle
prominent fused thalami
crescent-shaped frontal cortex
absent falx, corpus callosum, interhemispheric fissures
cyclopia
media cleft lip
hypotelorism
ethmocephaly
cebocephaly
microcephaly
sonographic features of alobar holoproscencephaly
posterior partial separation of hemispheres and ventricles
incomplete fusion of the thalami
rudimentary occipital horns
microcephaly
sonographic features of semilobar holoproscencephaly
absence of septum pellucidum
fusion of the frontal horns
variable fusion of the cingulated gyrus
Dandy-Walker complex
enlarged posterior fossa
high tentorium
upward displacement of the lateral sinuses
torcular herophili
vermian aplasia or hypoplasia
cystic dilation of the fourth ventricle
normal posterior fossa
enlarged cisterna magna
normal cerebellar vermis and fourth ventricle
arachnoid cyst
anterior displacement of the fourth ventricular and cerebellum
signs of Arnold-Chiari malformation
cisterna magna absent
Banana-shaped deformation of the cerebellum
lateral ventricular dilatation
sonographic features of lobar holoproscenphaly
Absent cavum septi pullucidi
wide high third ventricle
tear drop shaped ventricle
widened ventricular atria
laterally displaced ventricles
sunburst appearance of gyri and sulci
abnormal appearance of the cingulated and pericallosal arteries with color Doppler imaging
Sonographic features of Agenesis of Corpus Callosum
Neural plate development completes at _____ days
18-23
hypoechoic region within echogenic decidua identifies the _______
coeleomic cavity of the gestational sac
The neural tube differentiates into the primitive brain and spinal cord at _____
6 menstrual weeks
What 3 segments make up the brain?
proscencephalon
mesencephalon
rhombencephalon
forebrain
proscencephalon
midbrain
mesencephalon
hindbrain
rhombencephalon
Identification of the 3 segments can be made at ____ weeks
7-8
The proscencephalon becomes the ____ and _____
telencephalon
diencephalon
The forebrain develops into:
thalami
third ventricle
cerebral hemispheres
lateral ventricles
As the brain develops, the ______ takes its position in the posterior area of the lateral ventricles
choroid plexus
The _______ and ______ arise from the rhombencephalon.
metencephalon
myelencephalon
The upper portion of the fourth ventricle, pons, and cerebellum originate from the _______
metencephalon
The medulla and the rest of the fourth ventricle originate from the ______.
myelencephalon
The corpus callosum, cerebellar vermis, sulci and gyri, and migration of germinal matrix and myelination develop after _____ weeks.
15
Development of the corpus callosum completes approx at ______ weeks
18-20
The brain sulci and gyri image by ___ weeks
28
Critical period of brain development
3-16 weeks
Causes of congenital anomalies
lack of folic acid
exposure to toxoplasma gondii
exposure to high levels of radiation
measured at the level of the thalami and cavum septum pellucidi or columns of the fornix
Biparietal diameter
Proper placement for BPD
perpendicular to parietal bones and positioned at correct cephalocaudal position to intersect the third ventricle and thalami
3 sonographic rules for obtaining BPD
correct plane of section is through third ventricle and thalami
calvaria are smooth and symmetric bilaterally
position curses on outer edge of proximal skull to inner edge of distal skull
small head
microcephaly
A reliable indicator for _______ is a head perimeter two to three standard deviations or more below the mean for gestational age
microcephaly
forehead slopes and brain is small, with cerebral hemispheres affected to a greater extent than the diencephalic and rhombencephalic structures
microcephaly
_______ is frequently found in porencephaly, lissencephaly, and holoprosencephaly
microcephaly
Microcephaly may be associated with _____ and ______ factors.
environmental factors
genetic factors
large head
macrocephaly
HC two to three standard deviations above the mean for gestational age and se; enlarged ventricular system (hydrocephalus) or other intracranial anomalies
macrocephaly
enlarged ventricular system
hydrocephalus
Oblique cross section of the ___ is obtained at division of middle and anterior cerebral arteries, which lie anterior to cerebral peduncles.
ICA
major branch of circle of Willis in fetal brain
MCA
Carries more than 80% of cerebral blood flow
MCA
Fetal hypoxia worsens, ICA pulsatility index _____
decreases
MCA overlies the anterior ______ near base of skull
wing of Sphenoid bone
The correct angle of insonation for MCA is less than ___ degrees
15
bright echogenic, centrally placed vermis and two relatively nonechogenic hemispheres resembling a peanut indicates correct measurement level of:
cerebellar level
obtained through placement of calipers anteroposteriorly in the midline, between the vermis and the inner table of the occipital bone
measurement of cisterna magna
In regards to measurement of the cisterna magna, anything less than ____ mm is considered normal
10
Fetal biometry imaging is done between __ and ___ weeks
16
24
lateral ventricle can be be clearly seen using an endovaginal approach between __ and __ weeks
12
13
ovoid structure largely filled with choroid plexus
lateral ventricles
Lateral ventricles image by __ weeks using a transabdominal approach
16
prominent echogenic area within lateral ventricle
choroid plexus
highly vascular epithelial proliferation arising within the ependyma of the ventricle that produces and reabsorbs cerebrospinal fluid
choroid plexus
fills a large portion of the developing brain; has the form of two smooth, curve tubes joined above the third ventricle
ventricular system
Coronal section anterior to posterior visualizes:
corpus callosum
ventricular system
normal interhemispheric relationships
hypoechoic area between skull and cerebral cortex; diminishes in size throughout gestation as cerebral cortical matter expands to fill cranial vault
subarachnoid space
posterior coronal images visualize:
occipital horns of the lateral ventricles
cerebellum images inferior to fourth ventricle and superior to cisterna magna
Corpus callosum nearly fully developed by __-__ weeks
18
20
The corpus callosum images as a prominent, semilunar structure composed of three parts, from front to back:
genu
body
splenium
The posterior fossa contains:
cerebellum
fourth ventricle
cisterna magna
bright echogenic arc separating caudate nucleus from the thalamus
caudothalamic groove
highly vascular tissue in ependyma of lateral ventricle
germinal matrix
Most intracranial hemorrhages originate in the _______ in the preterm neonate
germinal matrix
closely spaced orbits
hypotelorism
wide spaced orbits
hypertelorism
outline lens of eyes; circular area on front of globe
cilaris muscle and zonular fibers
branch of opthalmic artery; may image within fetal globe
hyaloid artery
basal turn of cochlea or superior semicircular canal found within petrous portion of temporal bone
pinna
eyes develop as lateral projections from the telencephalon called optic vesicles at approximately day ____
28
By the end of the first month the optic cups positioned at end of an ______
optic stalk
By __ days the eye is an eye
48
decreased interorbital distance
hypotelorism
Hyptolerosim is most commonly associated with ______
holoproscenphaly
increased orbital distance
hypertelorism
4 syndromes associated with hypertelorism
Apert
Crouzon
Noonan
Pena-shokeir
Pfeiffer
decreased orbit size
microphthalmia
orbital diameter smaller than the 5th percentile for GA
microphthalmia
absence of the eye
anophthalmia
Hypertelorism is often accompanied by:
orbital teratomas
anterior encephaloceles
median cleft face syndrome
cleft lip
agenesis of the corpus callosum
Microphthalmia can be an isolated anomaly associated with ______ and _____
chromosomal abnormalities
intrauterine infections
tongue extending beyond teeth or alveolar ridge
macroglossia
Macroglossia may be caused by ______ of tongue or ______
large size
hypotonia
Macroglossia associations
trisomy 21
Beckwith Weidemann syndrome
hypothyroidism
storage diseases
neurofibromatosis
genetic syndromes
sublingual masses
severely hypoplastic mandible
micrognathia
Micrognathia can be seen with:
Pierre-Robin sequence
hemifacial microsomia
Micrognathia associated malformations
skeletal dysplasias
aneuplodies
teratogen exposure
Mandible anomalies put the fetus at high risk for:
respiratory distress
Facial development begins with _____ cells mirgrating into the head and neck area forming brachial arches
neural crest
The 1st set of arches are called ______ and develop into the face
mandibular arches
The 2nd set of arches are called the ______ and develop into the muscles of the face
hyoid
The development of the face occurs during the ___ week
5th
The frontal nasal prominences form:
upper mouth
maxilla
nose
Paired mandibular processes merge, resulting in formation of the ______
lower face
Maxillary and one of five prominences forming nose develop into:
upper lip
incisors
primary palate
Most frequent craniofacial anomalies
cleft lip and palate
Second most common congenital malformation
cleft lip and palate
most frequent anomaly found with finding of CL or CP
clubfoot
Isolated cleft lip and/or palate has a higher ______ incidence
female
defect of posterior portion with an intact upper lip and anterior palate
cleft palate
partial development of the brain
meroanencephaly
most common neural tube defect
meroanencephaly
fetus without a brain
anencephaly
absence of the entire skull, including skull base; thus, only a thin layer, if any, covers the brain
acrania
abnormally shaped cephalic pole, seen in late embryonic period (before week 10), altered appearance of brain cavities; decreased fluid content
acrania
absent cranial vault, usually seen between 10-14 weeks, reduced crown rump length, exposed nueral tissue with lobulated appearance (exencephaly)
anencephaly
loss of normal head contour with orbits marking the upper limit of the fetal face in the coronal plane
anencephaly
froglike appearance
anencephaly
associated malformations with anencephaly
spina bifida
CL/CP
clubfoot
omphalocele
complete or near complete absence of the cerebral cortex
hydranencephaly
causes of third trimester brain destruction
maternal toxoplasmosis
cytomegalovirus
herpes simplex
carbon monoxide exposure
suspected when there is a large fluid collection in the head with no recognizable cerebral cortex
hydranencephaly
rim of cerebral cortex around cystic cavity and enlargement of the third ventricle
severe hydrocephalus
lack of flow in anterior and MCAs with normal posterior cerebral artery flow
hydranencephaly
describes a variety of abnormalities of the brain and embryonic forebrain
holoprosencephaly
results in a single centrally located ventricle and a missing falx
holoprosencephaly
Holoprosencephaly can be caused by _______ and ______
poorly controlled maternal diabetes
teratogens
worst kind of holoprosencephaly
alobar
3 forms of holoprosencephaly
alobar
semilobar
lobar
_____ holoprosencephaly shows no evidence of division, falx cerebri and interhemispheric fissures absent, and single common ventricle and fused thalami
alobar
_____ holoprosencephaly demonstrates a partially separated brain
semilobar
______ holoprosencephaly shows almost complete separation of the hemispheres although frontal horns of lateral ventricles are fused, as are the thalami
lobar
holoprosencephaly associations
hypotelorism
CL and CP
nasal malformation
cyclopia
embryonic connective mass between the oral cavity and the undersurface of the neural tube; thought to be responsible for both the division of the prosencephalon and the production of the nasofrontal process
prechordial mesoderm
Nasofrontal process gives rise to _____, ____, and ______ bones and to the _____ and _____/
ethmoid
nasal
premaxillary
vomer
nasal septum
most severe facial malformation, presence of a single bony median orbit with a fleshy probscis above it
cyclopia
normally placed nose with one nostril
cebocephaly
large neural commissure connecting two cerebral hemispheres
corpus callosum
The corpus callosum begins development at ___ weeks
12
The ______ originates from lamina terminalis at anterior portion of third ventricle
corpus callosum
rare congenital disorder in which there is complete or partial absence of corpus callosum
agenesis of corpus callosum
The corpus callosum completes developement at ___ weeks making early detection difficult
20
“sunburst” lesion is associated with:
agenesis of corpus callosum
refers to a continuum of abnormalities of the posterior fossa that are distinct entities themselves
Dandy-Walker malformation
3 categories of Dandy Walker malformation
Dandy walker malformation
Dandy walker variant
mega cisterna magna
What is the most severe form of DWC?
Dandy Walker malformation
rare anomaly of the posterior fossa, complete or partial agenesis of cerebellar vermis, elevated tentorium
Dandy Walker malformation
partial agenesis of vermis without a large dilated fourth ventricle
Dandy Walker variant
normal cerebellar vermis and fourth ventricle
Mega cisterna magna
a group of sporadic brain malformations that results from dysgenetic development of the roof of the rhombencephalon
DWC abnormalities
superior displacement of the fourth ventricle, displacement of cerebellar vermis, compressed cisterna becomes potential space between dilated fourth ventricle and dura mater, hypoplastic anterolaterally displaced cerebrum images anterior to large posterior fossa cyst, possible hydrocephalus
Sonographic findings of DWC
Diagnosis of DWC occur after week ___
18
DWC associations
spina bifida
CP/CL
absence of the corpus callosum
Measurement of the posterior fossa from the posterior cerebellum to the anterior, internal portion of the skull is less than __ mm in the normal fetal brain
10
cerebral development disorder that involves disordered neuronal migration; results in unilateral and bilateral clefts in cerebral hemisphere that are lined by gray material within cerebal cortex
schizencephaly
There is a strong association between absent ____ and absence of the ______ with schizencephaly.
CSP
corpus callosum
rare cortical dysplasia resulting from impaired neuronal migration during the 12th and 16th weeks of gestation
lissencephaly
Depending on the point in gestation where disruption takes place in lissencephaly, three different outcomes
completely lack sulci and gyri (lissencephaly)
very few gyri (pachygyria)
very small gyri (microgyria)
Lissencephaly is associated with ____ and _____ predispositions.
environmental
genetic
Lissecephaly is diagnosed beyond ___ weeks when there is an inability to identify sulcations.
28
______ and _____ in the third trimester is an expected finding with lissencephaly.
hydramnios
IUGR
Facial dysmorphism is associated with:
prominent forehead
short nose
broad and flat nasal bridge
protuberant upper lip
Lissencephaly is associated with:
duodenal atresia
urinary tract abnormalities
congenital heart defects
cyptorchidism
inguinal hernia
clinodactyly
ear anomalies
protrusions of the meninges and frequently of brain substance through a defect in the cranium
cephaloceles
lesion containing brain tissue
encephalocele
protrusion o f meninges only through the defect
cranial meninogoceles
Occipital lesions make up __% of cephaloceles in caucasians of European descent
80
The ________ region is the most common location for cephaloceles in southeastern asia populations
frontoethmoidal
usually result from a defect in the neural tube closure; may also occur as part of a genetic or nongenetic syndrome;
cephaloceles
Cephaloceles are associated with:
amniotic band syndrome
cerebellar dysgenesis
cryptophthalmose syndrome
Meckel syndrome
paracranial mass not covered with bone
cephalocele
results when a large portion of the brain extrudes through a defect
microcephaly
develops because of impaired cerebrospinal fluid circulation; when brain tissue herniates, the result is a saclike complex mass caused by contained brain tissue
hydrocephalus
Cranial cephaloceles are very often associated with _____
ventriculomegaly
arise from the region of the neck, have multiple internal septations, and a thick wall, and are often associated with generalized soft tissue edema and hydrops
cystic hygromas
rare defect in the occiput of the cranium involving the foramen magnum with marked retroflexion of the fetal head and frequently a shortened spine
iniencephaly
Associated anomalies with ineincephaly
hydrocephalus
encephalocele
diaphragmatic hernia
omphalocele
Iniencephaly often occurs during the __ week of gestation
3rd
group of anomalies of the hindbrain prolapsing below level of foramen magnum
Arnold-chiari malformations
mild, where cerebellar tonsils displace more than 4 mm into foramen magna and posterior fossa contains fourth ventricle
Type I Arnold-Chiari malformation
congenital deformity characterized by displacement of cerebellar tonsils, parts of the cerebellum, fourth ventricle, pons, and medulla oblongata through the foramen magnum into the spinal canal
Type II Arnold-Chiari malformation
most severe form, associated with large herniation of posterior fossa contents with myelomeningocele and hydrocephalus
Type III Arnold-Chiari malformation
accompanies hypoplastic cerebellum with further herniation of brain into spinal canal
Type IV Arnold-Chiari malformation
What is the “banana sign” associated with?
Type II Arnold Chiari malformation
“lemon sign”
scalloping of frontal bones in axial section of head
abnormalities associated with Type II Arnold-Chiari malformation:
callosal dysgenesis
small third ventricle
enlarged interthalamic adhesions
a “beaked” tectum
polmicrogyria
hetertopias
skull deformities
colpocephaly
ventriculomegaly
abnormal increase in the volume of cerebral ventricles
ventriculomegaly
Ventriculomegaly may be caused by:
intraventricular and/or extraventricular obstruction
relative decrease in the amount of brain substance
increases in cerebrospinal fluid production
describes ventriculomegaly with increased intracranial pressure and head size; frequently associated with spina bifida
hydrocephalus
enlargement of the ventricles and cerebrospinal fluid displacement of choroid plexus
dangling Choroid plexus
Normal ventricle measurement
less than 10 mm
Mild ventriculomegaly measurement
10-15 mm
Severe ventriculomegaly measurement
more than 15 mm
Severe ventriculomegaly is often associated with ______ malformation
intracranial
congenital obstruction to flow of cerebrospinal fluid through aqueduct of Sylvius connecting the third and fourth ventricle
Aquaductal stenosis
round sonolucent areas in substance of choroid plexus of lateral ventricles; usually transient and without clinical significance resolving before end of 2nd trimester
choriod plexus cysts
Choroid plexus cysts are associated with:
trisomy 18 and other karyotypic abnormalities
Cysts that demonstrate internal septations and echogenic thick walls
choroid plexus cysts
destructive lesion of the brain that appears as one or several hypoechoic, cystic areas in the cerebral cortex, usually communicating with the ventricles
porencephaly
areas of prior ICH or tissue necrosis resorption, bilateral symmetric process, usually only occur in third trimester,
Porencephalic cysts
Porencephalic cysts are often associated with:
microcephaly
Causes of porencephaly
congenital infections
intrauterine narrowing
ICA and MCA occlusion
bleeding anywhere in the fetal cranium
intracranial hemorrhage
most common hemmorhage seen in the fetus; usually 48-72 hours after birth
intracranial hemorrhage
Intracranial hemorrhage may occur antenatally as a result of:
coagulopathy
amniocentesis
drug use
trauma
hyperechogenic mass in the region of the germinal matrix or within lateral ventricles
typical antenatal hemmorhage
3 types of cerebral AVMs
isolated AVM
AVM with vein of Galen Ectasia
varix of vein
elongated cystic structure at level of cistern of vein of Galen in third trimester represents the dilated, end-to-end arteries and veins without intervening capillaries
Aneurysm
cardiac overload seen with aneurysm of the Vein of Galen associations:
cardiomegaly
hepatosplenomegaly
soft tissue edema
polyhydramnios
nonimmune hydrops
The neural tube segments that become the brain are the _______, _______, and _______
prosencephalon
mesencephalon
rhombencephalon
The BPD level anatomy includes axial images of the :
thalami
third ventricle
smooth calvarial wall
brain/calvarium symmetry
_______ is a small head in proportion o the fetal face
Microcephaly
A large fetal head is ______
macrocephaly
The MCA carries __% of flow to the brain structures
80
Axial measurements of the cerebellum correlate to gestational age on a ___ to ___ ratio
one
one
A measurement of greater than __ mm of the ventricles obtained at the level of the atrium would be considered abnormal
10
________ exists with holoprosencephaly, cephaloceles, craniosynostosis, median cleft syndrome, and trisomy 18
hypertelorism
A tongue extending beyond the maxilla
macroglossia
Macroglossia has been found with _____ and ______
trisomy 21
Beckwith-Weidemann syndrome
hypoplastic mandible
micrognathia
Micrognathia is associated with _____, ______, ______, and ______ syndroms.
Pierre Robin syndrome
trisomy 18
trisomy 13
musculoskeletal
_____ are the most common facial abnormality
clefts
absence of the skull and cerebral hemispheres
meroenancephaly and anencephaly
demonstrates bulging fetal orbits with a froglike appearance on the imgage
meroenencephaly
Polyhydramnios, facial bones, and increased fetal activity are seen within the ______ fetus
meranencephalic
absence of the skull and may or may not have coexisting brain tissue
acrania
a destructive lesion of the brain resulting in a large anechoic area within the cranial vault surrounded by midbrain and basal ganglia
hydranencephaly
_______, seen with trisomy 13, is an abnormal development of the fetal brain
Holoprosencephaly
failure of all or part of the corpus callosum to develop
agenesis of the corpus callosum
demonstrates a large cisterna magna, with an enlarged fourth ventricle and flattened cerebellar hemispheres
DWC
Abnormal clefting of the brain
schizencephaly
A smooth brain
lissencephaly
_______ syndrome results in lack of sacral development
Caudal regression
The herniation of intracranial contents through a cranial defect
cephalocele
the displacement of the posterior fossa brain structures through the foramen magna into the cervical canal
Arnold-Chiari malformations
Large ventricles, ______, are the result of multiple causes and are often called _______
ventriculomegaly
hydrocephalus
The choroid plexus:
a. invaginates into the ventricles
b. is hyperechoic
c. is positioned in the anterior ventricle
d. initially takes up approximately 1/3 of the cerebral hemisphere
a
The metecephalon and myelencephalon are part of the:
a. myelencephalon
b. prosencephalon
c. rhombencephalon
d. mesencephalon
c
The corpus callosum, cerebellar vermis, sulci, gyri, migration of the germinal matrix, and myelination, develop after:
15 weeks gestation
BPD is measured at the level of the ______ and columns of fornix
thalami
What is the alternative measurement to BPD?
HC
The most studied artery in the fetal brain is the:
MCA
A normal cisterna magna measurement is less than:
1cm
The most frequent anomaly noted with a cleft palate or cleft lip is:
clubfoot
Fetuses with hypoplastic mandible anomalies are at risk of acute neonatal:
respiratory distress
Sonographic features of meroanencephaly include:
a. frog-like appearance
b. CL
c. hydranencephaly
d. acrania
a
A fetal brain with no recognizable cerebral cortex and defined thalami and cerebellum is:
hydranencephaly
Agenesis of the corpus callosum reveals all except:
a. wide high third ventricle
b. laterally displaced ventricles
c. absent cavum septi pellucidi
d. hypertelorism
d
Dandy-Walker malformation consists of:
a. hypertrophy of the third ventricle
b. marked cystic dilation of the fourth ventricle
c. marked cystic dilation of the lateral ventricles
d. enlargement of the anterior horns
b
Lissencephaly is an absence or paucity of gyri resulting in the characteristic appearance of:
a. a smooth cerebral surface after 20 weeks
b. absent sulci after 20 weeks
c. an enlarged CM
d. a decreased lateral ventricular measurement
a
A markedly retroflexed neck is an indication of:
iniencephaly
A correct measurement of the BPD involves placing two cursors at the:
a. inner margins of the cranium
b. outer margins of the cranium
c. outer edge of the proximal skull to the inner edge of the distal skull
d. inner edge of the parietal bones
c
A long narrow head is:
dolichocephaly
Enlargement of the ventricles and cerebrospinal fluid displacement of the choroid plexus results in a condition called:
dangling choroid plexus
Bleeding anywhere in the fetal cranium is known as all except:
a. intraparenchymal hemorrhage
b. subdural hematoma
c. germinal matrix hemorrhage
d. petechial hemorrhage
d
A measurement of the lateral ventricular atrium should not exceed:
a. 1 cm
b. 1 mm
c. 8 m
d. 2 cm
a
The forebrain is also known as the:
prosencephalon
Many brain structures develop between week __________, resulting in this time frame being identified as the critical period of brain developemtn
3
16
The great cerebral vein is also called:
The vein of Gallen
The third ventricle is positioned between the _____ and the frontal horns of the lateral ventricles
thalami
A microcephalic fetus may demonstrate ______ ventricles.
enlarged
The best angle of insonation to obtain peak velocity of the MCA is less than ____ degrees.
15
A decreased interorbital distance
hypotelorism
Between _____ weeks of gestation, te transverse cerebellar diameter measured in millimeters correlates 1:1 with gestation age
16
24
Holoprosencephaly is divided into _____, _______, and ______ varieties, defined by the degree of separation of the cerebral hemispheres
alobar
semilobar
lobar
_______ is a cerebral developmental disorder that involves disordered neuronal migration
schizencephaly
Protrusions of the meninges and frequently of brain substance through a defect in the cranium is ______
cephaloceles
The term for small head is
microcephaly
To obtain the MCA peak velocity, image the fetal head in a ______ plane.
transverse
The presence of a single median bony orbit with a fleshy proboscis above it is ______
cyclopia
Arnold-chiari malformations often have accompanying _______.
spina bifida
The BPD maintains its closest correlation with gestational age in the ____ and _______ trimester.
first
early second
________ is an abnormal increases in the volume of the cerebral ventricles
ventriculomegaly
A sonolucent area in the choroid plexus is known as ______
choroid plexus cysts
Macrocephaly is defined as a head circumference _____ standard deviations ______ the mean for gestational age and sex.
2-3
above
The tongue extending beyond the teeth or alveolar ridge is
macroglossia
