fetal head and brain Chapter 24

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subdivision within the middle of the lip

(median) cleft lip

what are the 3 main types of holoprosencephaly?

-alobar -semilobar -lobar

2 main subtypes of acrania:

-anencephaly -exencephaly

Alobar holoprosencephaly is diagnosed when there is absence of the:

-corpus callosum -cavum septum pellucidum -third ventricle -interhemispheric fissure -falx cerebri

In the presence of spina bifida, there are several notable changes that occur within the brain and skull.

-lemon sign -banana sign

anencephaly and spina bifida occur ___ per ________ pregnancies

1 out of 1,000

(ventriculomegaly) atrial diameter measures greater than ___ mm

10

Present when only the cisterna magna is enlarged, measuring more than ______ in depth.

10mm

Pathway for communication between the hemispheres and is completely formed by

18 weeks

choroid plexus cysts regress by the?

3rd trimester

___of folic acid significantly reduces the chances of a neural tube defect

4mg

Their nonexistence has been linked to as many as 50 to 200 different syndromes and anomalies

AGENESIS OF THE CORPUS CALLOSUM AND CAVUM SEPTUM PELLUCIDUM

There can be partial or complete absence of the corpus callosum

AGENESIS OF THE CORPUS CALLOSUM AND CAVUM SEPTUM PELLUCIDUM

absence of one or both eyes

Anophthalmia

Usually caused by narrowing of the cerebral aqueduct (AKA Aqueduct of Sylvius), between 3rd & 4th ventricle.

Aqueductal stenosis

is the most common cause of hydrocephalus in utero.

Aqueductal stenosis

_______________ is a group of cranial abnormalities associated with the neural tube defect spina bifida.

Arnold-Chiari 2 or Chiari 2 malformation

Most often, if the corpus callosum is absent, the _______ will be absent as well.

CSP

small frontal horns and enlarged occipital horns (teardrop-shaped lateral ventricles.)

Colpocephaly

Sono findings: -Enlargement of the cisterna magna greater than 10mm in the AP dimension -Communication of the enlarged cisterna magna with a dilated fourth ventricle -Agenesis or hypoplasia of the cerebellar vermis -Varying degrees of ventriculomegaly.

DWM

_____ is thought to be caused by a developmental abnormality in the roof of the fourth ventricle.

DWM

acrania aka

Exencephaly -anenecephaly

A fatal condition where the entire cerebrum is replaced by a large sac containing CSF.

Hydranencephaly

The brainstem and basal ganglia are maintained and surrounded by CSF

Hydranencephaly

The falx cerebri may be partially or completely absent.

Hydranencephaly

There will be NO cerebral cortex identified

Hydranencephaly

severe cases of ventriculomegaly caused by an obstruction of CSF.

Hydrocephalus

SONO FINDINGS: -Enlargement of the cisterna magna greater than 10mm in the AP dimension -Normal cerebellum and fourth ventricle

Mega Cisterna Magna

A rare condition in which a cyst communicates with the ventricular system.

PORENCEPHALY

is associated with the development of fluid-filled clefts within the cerebrum.

Schizencephaly

radial arrangement of the sulci.

Sunburst sign

maternal serum is screening for?

TORCH

sono findings: calcifications around ventricles

TORCH

TORCH infections

Toxoplasmosis Other Rubella Cytomegalovirus Herpes

SONO APPEARANCE: Atrium of lat ventricle >10mm >15mm moderate/marked Dangling choroid sign

VENTRICULOMEGALY/ HYDROCEPHALUS

_____________ has been cited as the most common cranial abnormality.

Ventriculomegaly

the abnormal enlargement of the ventricles.

Ventriculomegaly

Defined as the absence of the cranial vault above the bony orbits

acrania

Elevated and dilated third ventricle.

agenesis of the CC and CSP

Partial or complete absence of the corpus callosum & absence of the CSP (after 18 weeks)

agenesis of the CC and CSP

most severe holoprosencephaly, often results in neonatal death

alobar

Sono Appearance: -Horseshoe-shaped monoventricle -Fused echogenic thalami -Absence of cavum septum pellucidum, interhemispheric fissure, falx cerebri, corpus callosum, & third ventricle -Normal cerebellum and brainstem

alobar holoprosencephaly

There will be evidence of a horseshoe-shaped monoventricle and the lobes of the thalamus will be fused and echogenic in appearance.

alobar holoprosencephaly

there are no cerebral hemispheres present.

anencephaly

what are the most common neural tube defects?

anencephaly and spina bifida

_______________ will not communicate with the ventricular system

arachnoid cysts

cerebellum will become displaced inferiorly and posteriorly and appear curved

banana sign

the cisterna magna is completely obliterated with which sign of spina bifida?

banana sign

the _________ located inferior to the corpus callosum, and the corpus callosum develop at the same time.

cavum septum pellucidum

close-set eyes w/ one single nostril within the nose

cebocephaly

__________ are common findings in Meckel-Gruber syndrome and a have varying sonographic appearances based on their content?

cephaloceles

are protrusions of intracranial contents through a defect in the skull

cephaloceles

______________ are cysts located within the choroid plexus of the lateral ventricles

choroid plexus

Sono Findings: -Anechoic, round, smooth-walled cyst located within the choroid plexus of the lateral ventricle. -Measure greater than 2mm

choroid plexus cysts

Found within the choroid plexus and increases the production of cerebrospinal fluid?

choroid plexus papillomas

leads to ventriculomegaly

choroid plexus papillomas

Frontal horns will be small and slitlike, while the occipital horns will be enlarged, a condition known as?

colpocephaly

obstruction lies outside the ventricular system.

communicating

2 Types of Hydrocephalus:

communicating and non-communicating

is a bridge of tissue located within the midline of the brain that connects the two cerebral hemispheres.

corpus callosum

-will appear as a solid echogenic mass -may also be present with agenesis of the corpus callosum

corpus callosum lipomas

orbits are fused containing a single eye

cyclopia

___________________ involves posterior fossa abnormalities that involve the cystic dilatation of the cistern magna and fourth ventricle.

dandy-walker complex

mega cisterna magna may be confused with?

dandy-walker malformation

______________ is actually a type of classification of dandy-walker complex

dandy-walker malformation (DWM)

the most common location of spina bifida is within the?

distal lumbosacral region

involves a normal amount of cerebral tissue

exencephaly

holoprosencephaly may be detected with EV as early as the?

first trimester

___________ is normal with mega cisterna magna and enlarged with DWM.

fourth ventricle

The lateral ventricle _______________ from the transducer will be the easiest to visualize.

furthest away

A midline brain anomaly that is associated with brain aberrations (not normal) and atypical facial structures.

holoprosencephaly

Trisomy 13, or Patau syndrome, is present in 50 to 70% of fetuses diagnosed with

holoprosencephaly

Bilateral occlusion of the ICA's causing destruction of the cerebral hemispheres can cause?

hydranencephaly

Brain may have a normal appearance in 1st trimester, then reflect this condition in the 2nd or 3rd trimester.

hydranencephaly

Intrauterine infections such as cytomegalovirus and toxoplasmosis can cause?

hydranencephaly

Sono Findings: -Fluid-filled cranium -Absent or partial absence of the falx cerebri -Maintained brain stem and basal ganglia -No identifiable cerebral cortex

hydranencephaly

___________ is typically a fatal condition, with death occurring in the first year of life.

hydranencephaly

Prevents the CSF flow from the 3rd to 4th ventricle.

hydrocephalus

With ___________________ (usually caused by aqueductal stenosis)...dilation of all of ventricular system EXCEPT 4th ventricular remains normal

hydrocephalus

Reduced distance between the orbits

hypotelorism

frontal bones become flattened and will yield a lemon shape to the cranium

lemon sign

Agyria + the absence of sulci within the brain is not typically diagnosed until the third trimester or postnatally and almost always carries a poor prognosis.

lissencephaly

SONO FINDINGS: Lack of sulci and gyri within the cerebrum

lissencephaly

means smooth brain

lissencephaly

there are no gyri within the cerebral cortex

lissencephaly

consistent with life holoprosencephaly

lobar

the enlargement of the cisterna magna without the involvement of the fourth ventricle

mega cisterna magna

protrusion of meninges

meningocele

Hydrocephalus can be described as:

mild, moderate, or severe.

protrusion of meninges and spinal cord

myelomeningocele

________ occur when the embryonic neural tube fails to close.

neural tube defects

the obstruction level is within the ventricular system.

non-communicating

the most common location of a cephalocele?

occipital region

Arachnoid cysts can be confused with __________?

porencephaly

SONO FINDINGS: -Cystic mass that communicates with the lateral ventricle -Most often unilateral

porencephaly

They can occur after the fetus has experienced hemorrhage within one or both of the cerebral hemispheres.

porencephaly

a false nose situated above the orbits

proboscis

Sono Appearance: A cerebrum containing clefts filled with anechoic, cerebrospinal fluid.

schizencephaly

Screening for neural tube defects is achieved by a combination of

sonography, amniocentesis, and/or maternal serum screening.

___________ may result in a mass that protrudes from the spine

spina bifida

lateral venrtricles will also be distorted in shape with what condition?

spina bifida

________ contains tissues such as hair, sebum, and fat

teratoma

appear as complex masses that distort the normal brain structures

teratoma

the most common intracranial tumor?

teratoma

choroid plexus cyst they are associated with an increased risk of?

trisomy 18

Schizencephaly etiology?

unknown

With _________________...any part of ventricular system can be dilated

ventriculomegaly


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