OB CHP. 24

The cerebellum grows at a rate of what per week between what weeks?

1 mm per week between 14 and 21 weeks

The normal lateral ventricle does not typically measure more than what at the level of the atrium?

10 mm

The biparietal diameter measurement is typically done when?

13 and 14 weeks

The corpus callosum forms late in gestation but should be completely intact between when?

18 and 20 weeks

The fourth ventricle has how many apertures?

3

The ventricular system is composed of how many ventricles? What is the function?

4, provide cushioning for the brain

By what week does the neural plate develop?

4.5 weeks

The skull consists of how many cranial bones?

8

The corpus callosum functionally provides what?

A pathway for communication between the hemispheres and is completely formed by 18 weeks

What are the sonography findings of acrania / anencephaly?

Absent cranial Vault, some cerebro tissue may be present, frog like faces or bulging eyes

What is the most severe form of holoprosencephaly?

Alobar

What are the three main types of holoprosencephaly?

Alobar, semilobar, lobar

How does the cave of septum pellucidum appear?

Anechoic box shaped structure in the axial scan plane

What are the sonography findings of choroid plexus cyst?

Anechoic round smooth walled cyst located within the choroid plexus of the lateral ventricle

The most severe form of holoprosencephaly

Anencephaly

Acrania can be further divided into what two subtypes?

Anencephaly and exencephaly

What are the most common neural tube defects?

Anencephaly and spina bifida

The absence of the eyes

Anophthalmia

cavum septum pellucidum can be identified where?

Anterior portion of the brain between the frontal horns of the lateral ventricles

The fourth ventricle is located where?

Anterior to the cerebellum within the midline of the brain

The abnormal narrowing of the cerebral aqueduct

Aqueduct stenosis

Benign cyst within the brain that do not communicate with the ventricular system

Arachnoid cyst

Arachnoid Villi AKA?

Arachnoid granulations

Nodular structures located along the falx cerebri that reabsorb cerebrospinal fluid into the venous system

Arachnoid granulations

What are responsible for the reabsorption of CSF into the venous system?

Arachnoid granulations AKA arachnoid villi

The middle layer of the meninges

Arachnoid membrane

A group of cranial abnormalities associated with spina bifida

Arnold Chiari 2 malformation

For lateral ventricle measurement where are the calipers placed?

At the level of the glomus of the choroid plexus

What is the formula used to calculate the cephalic index?

BPD /OFD x 100

A group of nuclei within the brain that function in several ways including information processing and emotional response

Basal ganglia

Where are the locations of coronal suture, sagittal suture, lambdoidal suture, squamosal suture, metopic suture?

Between the frontal and two parietal bones, between the two parietal bones, between the parietal bones and occipital bones, between the parietal bones and temporal bones, located within the frontal bone along the midline of the forehead

What could be the causes of hydranencephaly?

Bilateral occlusion of the internal carotid arteries with subsequent destruction of cerebral hemispheres

Where is the location and when does the closure of the following frontanelle: Anterior or frontal, posterior or occipital, anterolateral or sphenoidal, posterolateral or mastoid

Bordered by frontal and parietal bones by 18 months, bordered by occipital and parietal Bones by 6 months, bordered by frontal parietal and sphenoid Bones by 2 years, bordered by mastoid and occipital bones by 2 years

Where are the paired lateral ventricles located?

Both sides of the falx cerebri within the cerebal hemispheres

Where are the two lobes of the thalamus located?

Both sides of the third ventricle

The lower part of the brain composed of the pons, midbrain, medulla oblongata

Brain stem

Encephalocele will have what content of the mass?

Brain tissue only

The anterior fontanelle when completely filled with bone is referred to as what?

Bregma

Close-set eyes hypothyroidism and a nose with a single nostril

Cebocephaly

The ratio used for assessing fetal head shape

Cephalic index

What are protrusions of the inter-cranial contents through a defect in the skull?

Cephalocele

The portion of the cerebellum located within the midline of the brain that connects it's two hemispheres

Cerebellar vermis

The duct that connects the third ventricle of the brain to the fourth ventricle AKA Aqueduct of sylvius

Cerebral aqueduct

Paired structures located anterior to the cerebral aqueduct

Cerebral peduncles

The protective and nourishing fluid of the brain and spinal cord produced by the cells of the choroid plexus

Cerebrospinal fluid

The brain can be divided into what two parts?

Cerebrum and cerebellum

Specialized cells within the ventricular system responsible for cerebrospinal fluid production

Choroid plexus

A prominent space within the skull that contains cerebrospinal fluid, a cistern is created by the separation of the arachnoid membrane and Pia Mater

Cistern

What is the largest cistern in the head? How does it appear sonography?

Cisterna magna, anechoic fluid-filled space posterior to the cerebellum between the cerebellar vermis and the interior surface of the occipital bone may have septations

the abnormal lateral ventricle shape in which there is a small frontal horn and enlarged occipital horn

Colpocephaly

What are the two main types of hydrocephalus?

Communicating and noncommunicating

The obstruction of cerebrospinal fluid from a source outside of the ventricular system

Communicating hydrocephalus

A thick band of white matter that provides communication between right and left halves of the brain

Corpus callosum

Dolichocephaly head shape is associated with what anomaly?

Craniosynostosis

The premature close of the cranial sutures with subsequent Fusion of the cranial bones

Craniosynostosis

Brachycephaly head shape is associated with what anomaly?

Craniosynostosis, trisomy 21, 18

Fusion of the orbits

Cyclopia

A spectrum of posterior fossa abnormalities that involve the cystic dilation of the cisterna magna and fourth ventricle

Dandy-Walker complex

Congenital brain malformation in which there is an enlargement of the cisterna magna, agenesis of cerebellar vermis and dilation of fourth ventricle

Dandy-Walker malformation

A sonographic sign associated with hydrocephalus when the choroid plexus is noted hanging freely within the dilated lateral ventricle

Dangling choroid sign

What is the prognosis of hydranencephaly?

Death usually in the first year of life

What is the most common location of spina bifida?

Distal lumbosacral region

With a cephalic index of less than 75 it denotes what? More than 85 denotes what?

Dolichocephalic shape, brachialcephalic shape

Scaphocephaly AKA?

Dolichocephaly

An elongated narrow head shape AKA scaphocephaly

Doliochocephaly

A form of acrania and which the entire cerebrum is located outside of the skull

Exencephaly

A double fold of dura mater located within the midline of the brain

Falx cerebri

What are the sonography findings of hydranencephaly?

Fluid-filled Cranium, absent or partial absence of falx cerebri, maintained brainstem and basal ganglia, no identifiable cerebal cortex

A vitamin that has been shown to significantly reduce the likelihood of neural tube defects AKA folic acid

Folate

The opening in the base of the skull through which the spinal cord exits

Foramen magnum

What are the several notable changes that occur with spina bifida in the brain and skull?

Frontal bones become flattened and will yield a lemon shape, cerebellum will become displaced inferiorly and posteriorly and appear curved in a presents like banana sign, the cisterna magna is completely obliterated, lateral ventricles distorted, frontal horns will be small in slit like

What are the six cerebral lobes?

Frontal lobe, two temporal lobes, two parietal lobes, occipital lobe

Each lateral ventricle consist of what?

Frontal, temporal, occipital horn

Herniation of abdominal contents through a right-sided Periumbilical abdominal abdominal wall defect

Gastroschisis

A group of thin-walled blood vessels and cells within the subependymal layer of the fetus brain responsible for brain cell migration during fetal development

Germinal Matrix

The largest part of the choroid plexus

Glomus

What are the bilateral brain structures?

Hemispheres of cerebellum and cerebrum, lobes of the thalamus, Foreman of Monroe, lateral ventricles, choroid plexus

A group of brain abnormalities consisting of varying degrees of fusion of the lateral ventricles absence of the midline structures and Associated facial anomalies

Holoprosencephaly

Name the midline brain anatomy

Hulk cerebri, interhemispheric fissure, corpus callosum, cavum septum pellucidum, third ventricle, Aqueduct of sylvius, fourth ventricle, cerebellar vermis, cisterna magna, interthalamic adhesion

A fatal condition in which the entire cerebrum is replaced by a large sac containing cerebrospinal fluid

Hydranencephaly

An abnormal accumulation of fluid in at least two fetal body cavities

Hydrops

How do fetal sutures appear sonographically?

Hypoechoic spaces between the bone

Incomplete growth of a structure or organ

Hypoplasia

Reduced distance between the orbits

Hypotelorism

A shortage of oxygen or decreased oxygen in the blood

Hypoxia

Groove within the midline of the brain that divides the two cerebral hemispheres

Interhemispheric fissure

The falx cerebri is located within where?

Interhemispheric fissure

The mass of tissue located in the third ventricle within the midline of the brain which connects the two lobes of the thalamus AKA Massa intermedia

Interthalamic adhesion

The posterior fontanelle is referred to as what when completely filled with bone?

Lambda

Flow of CSF through ventricles

Lateral ventricles -> interventricular foramen -> third ventricle -> aqueduct of the midbrain -> fourth ventricle -> lateral apertures (Lushka) or median aperture (Magendie) -> subarachnoid space of brain and spinal cord

What are the sonographic findings of Arnold Chiari malformation?

Lemon sign, banana son, obliteration cisterna magna, Colpocephaly, enlarged Massa intermedia, hydrocephalus, open spinal defect

An enlarged head circumference

Macrocephaly

what is the most common risk factor for fetal intrauterine intracranial hemorrhage?

Maternal platelet disorders

A subdivision within the midline of the lip

Medial cleft lip

Measurement more than 10 mm of the cisterna magna is consistent with what? Less than 2 millimeters is worrisome for what?

Mega cisterna magna and Dandy-Walker complex,, Arnold Chiari 2 malformation

The coverings of the brain and spinal cord

Meninges

Meningocele will have what content of the mass?

Meninges only

Meninges herniation of the cranial or spinal meninges due to an open cranial or spinal defect

Meningocele

Meningocele the primary brain vesicle AKA midbrain, becomes the cerebral peduncles,quadrigeminal plate and cerebral aqueduct

Mesencephalon

Normal head shape

Mesocephalic

Small head

Microcephaly

Doppler of what artery has been shown effective at evaluating for hypoxia?

Middle cerebral artery

The early embryologic structure that develops into the central nervous system

Neural plate

Embryologic formation that results from the fusion of the two folded ends of the neural plate

Neural tube

Neural tube defects occur when what?

Neural tube fails to close

The neural plate will give rise to what?

Neural tube which will become the spine and brain

When is anencephaly considered?

No cerebral hemispheres present

The obstruction of cerebrospinal fluid from a source within the ventricular system

Non communicating hydrocephalus

When is exencephaly considered?

Normal amount of cerebral tissue

Arnold Chiari 2 malformation will have a sonographic finding of what as this is a posterior fossa abnormality?

Obliterated cisterna magna, banana shaped cerebellum, lemon shape skull

The most common location for a cephalocele is where?

Occipital region

Head circumference can be obtained by measuring the what diameter?

Occipitofrontal diameter

And anterior abdominal wall defect where there is a herniation of the fetal bowel and other abdominal organ into the base of the umbilical cord

Omphalocele

What are the sonography findings of cephalocele?

Open cranial defect, small or obliterated cisterna magna, complex Mass protruding from the cranium

The functional part of an organ

Parenchyma

What are the sonographic findings of agenesis of the corpus callosum and cavum septum pellucidum?

Partial or complete absence of the corpus callosum and absence of the cavum septum pellucidum after 18 weeks, Sunburst sign radial arrangement of the sulci, Colpocephaly small frontal horns and a large occipital horns, elevated and dilated third ventricle

A chromosomal aberration in which there is a third chromosome 13 AKA Trisomy 13

Patau syndrome

The innermost layer of meninges

Pia Mater

The primary brain vesicle AKA for brain becomes the lateral ventricles, cerebral hemispheres, third ventricle, thalamus, hypothalamus , pineal gland, pituitary gland

Prosencephalon

Initially the brain is separated into what three primary vesicles?

Prosencephalon, mesencephalon, rhombencephalon

The primary vein bicycle AKA hindbrain becomes the cerebellum, pons, medulla oblongata, fourth ventricle

Rhombencephalon

The cerebrum can be further divided into what?

Right and left hemisphere

A group of neural tube defects that describe some manifestation of incomplete closure of the spine

Spinal dysraphism

The normal cerebrum contains multiple what?

Sulci and gyri

The most common intracranial tumor found in utero is what?

Teratoma

a brain structure that allows communication between the senses as well as performing many other functions

Thalamus

The most common lethal skeletal dysplasia characterized by a Cloverleaf skull with frontal bossing and hydrocephalus

Thanatophoric dysplasia

The point at which the body, temporal horn, occipital horn meet is called what?

Trigon or atrium of the lateral ventricle

Chromosomal aberration in which there is a third chromosome 13 AKA patau syndrome often associated with holoprosencephaly

Trisomy 13

Choroid plexus cysts are associated with a risk of what?

Trisomy 18

Chromosomal aberration in which there is a third chromosome 21 AKA Down syndrome

Trisomy 21

The cerebellum consists of how many hemispheres? Where are they located? What do they look like?

Two hemispheres, right and left, located under surface of cerebellum is the cerebellar tonsils, normal shape is dumbbell shape or Figure 8

the structure located between the two lobes of the cerebellum is the:

a. cerebellar vermis

the interthalamic adhesion (massa intermedia) passes through the:

a. third ventricle

dangling choroid sign is associated with:

a. ventriculormegaly

a lemon-shaped skull is related to:

b. Arnold-Chiari II malformation

which of the following will also typically be absent with agenesis of the corpus callosum? a. cerebellar vermis b. CSP (cavum septum pellucidum) c. third ventricle d. fourth ventricle

b. CSP

the "sunburst" of the cerebral sulci is a sonographic finding of:

b. agenesis of the corpus callosum

the most severe form of holoprosencephaly is:

b. alobar

the band of tissue that allows communication between the right and left cerebral hemispheres is the:

b. corpus callosum

which of the following should not be included in the correct level for an HC measurement? a. falx cerebri b. fourth ventricle c. thalamus d. CSP

b. fourth ventricle

which of the following would not be normally located within the midline of the fetal brain? a. CSP b. lobes of the thalamus c. third ventricle d. falx cerebri

b. lobes of the thalamus

Round skull shape

brachycephaly

absence of the skull is:

c. acrania

the fourth ventricle is located:

c. anterior to the cerebellar vermis

the third ventricle is located: a. anterior to the thalamus b. anterior to the cerebellar vermis c. between the two lobes of the thalamus d. superior to the corpus callosum

c. between the two lobes of the thalamus

enlargement of the frontal horns and narrowing of the occipital horns is termed:

c. colpocephaly

which of the following is located on both sides of the midline? a. interhemispheric fissures b. third and fourth ventricles c. lateral ventricles d. third ventricle and cerebral aqueduct

c. lateral ventricles

a cisterna magna that measures 15mm and a normal appearing cerebellum is most likely:

c. mega cisterna magna

a normal shaped skull is termed:

c. mesocephaly

what chromosomal aberration is most often associated with holoprosencephaly?

c. trisomy 13

a strawberry-shaped skull is commonly associated with:

c. trisomy 18

A normal midline brain structure identified in the anterior portion of the brain between the frontal horns of the lateral ventricles

cavum septum pellucidum

the anechoic midline brain structure located between the frontal horns of the lateral ventricles is the:

cavum septum pellucidum

the ______ is the largest part of the brain

cerebrum

the largest cistern in the skull; located in the posterior portion of the skull

cisterna magna

the cerebellum is measured in transverse at the same level as the

cisterna magna and thalamus

the cisterna magna should not exceed ______ in the transcerebellar plane

d. 10mm

the third ventricle communicates with the fourth ventricle at the:

d. aqueduct of Sylvius

the double fold of dura mater that divides the cerebral hemispheres is the:

d. falx cerebri

what fetal suture is located within the frontal bone along the midline of the forehead?

d. metopic suture

all of the following are sonographic findings of Arnold-Chiari II malformation except: a. enlarged massa intermedia b. hydrocephalus c. obliteration of the cisterna magna d. strawberry sign

d. strawberry sign

a cloverleaf-shaped skull is related to:

d. thanatophoric dysplasia

the choroid plexus cyst could be associated with an increased risk of:

d. trisomy 18

cranial bones:

ethmoid, frontal, occipital, parietal, sphenoid, and temporal

biparietal diameter (BPD)

fetal transverse cranial diameter at the level of the thalamus and cavum septum pellucidum

BPD is measured from

outer and inner

the cerebellum is located in the ______ ______ of the cranium

posterior fossa

Initially the brain is separated into three primary vesicles termed the

prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain)

BPD and HC are taken at the level of the

thalami and cave septum pellucidum and third ventricle

the ______ ventricle runs straight through the thalamus

third