Chapter 23: Sonographic Assessment of the Fetal Head Flashcards by Billie Harney

congenital absence of one or both eyes

anophthalmia

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short broad head because of premature suture fusion

brachycephaly

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congenital anomalies of the head caused by teratogens or development disruptions of the nervous system

cebocephaly

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congenital brain anomaly resulting from a migrational defect of the occipital horns of the lateral ventricles leading to ventricular enlargement

colpocephaly

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long narrow head

doliocephaly

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abnormally formed organs

dysgenesis

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malformation of an organ or structure

dysmorphic

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dilatation or distention of a hollow structure

ectasia

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nostrils

nares

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either the rostral or caudal end of the neural tube

neuropore

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graph

nomogram

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disease characteristic

pathognomonic

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posterior displacement of the maxilla and mandible

retrognathia

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toward the cephalic or head end

rostral

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substance that interferes with embryonic development

teratogen

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central portion of the cerebellum between the hemispheres

vermis

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axial biparietal diameter of brain

thalami
third ventricle
cavum septum pellucidi

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axial cerebellum

cerebellum
cisterna magna
vermis

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axial ventricles

ventricles
choroid plexus

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coronal face

soft tissues of the nose, lips, chiin

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sagittal profile

confirm correct symmetry of forehead, nose, lips, chin

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Sonographic features of cleft lip/palate in axial view

linear defect through the maxilla/lip

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Sonographic features of cleft lip/palate in coronal view

linear defect from nose to oral rim

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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

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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.

Development of the corpus callosum completes approx at ______ weeks

18-20

The brain sulci and gyri image by ___ weeks

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

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

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

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 ____

By the end of the first month the optic cups positioned at end of an ______

optic stalk

By __ days the eye is an eye

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

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

"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 ___

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

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.

______ 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

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

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

________ 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

The metecephalon and myelencephalon are part of the: a. myelencephalon b. prosencephalon c. rhombencephalon d. mesencephalon

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?

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 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

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

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 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

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

A measurement of the lateral ventricular atrium should not exceed: a. 1 cm b. 1 mm c. 8 m d. 2 cm

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.

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

Chapter 23: Sonographic Assessment of the Fetal Head Flashcards

(286 cards)