Chapter 24 fetal head and brain
Dandy-Walker malformation
*Enlargement of cisterna magna *Agenesis of cerebellar vermis *Dilation of fourth ventricle
Macrocephaly Head Shape: Associated Anomalies
*Hydrocephalus *Hydranencephaly *Intracranial tumors *Familiar inheritance *Beckwidth-Wiedemann syndrome
Microcephaly Head Shape: Associated Anomalies
*TORCH infections *Trisomy 13 *Trisomy 18 *Meckel-Gruber syndrome *Fetal alcohol syndrome
Dangling choroid plexus
A sono sign assoc w ventriculomegaly when the choroid plexus is noted hanging freely within dilated lateral ventricles
corpus callosum
A thick band of white matter that provides communication between right and left halves of the brain
Colopocephaly
Abnormal lateral ventricle shape in which there is a small frontal horn and enlarged occipital horn
omphalocele
Anterior abdominal wall defect where there is herniation of fetal bowel & other abdominal organ into base of umbilical cord
The third ventricle connects to the fourth ventricle inferiorly by a long tube called ?
Aqueduct of Sylvius or cerebral aqueduct
The BPD is obtained in an axial plane at the level of?
CSP, THALAMUS, FALX CEREBRI
Sono findings of Aqueductal stenosis
Dilation of the lateral ventricles and the third ventricle FOURTH VENTRICLE REMAINS NORMAL
Meckel-Gruber syndrome
Fetal syndrome associated with microcephaly, occipital encephalocele, polydactyly, and polycystic kidneys
Triplody
Fetus that has three of every chromosome
Exencephaly
Form of acrania in which entire cerebrum is located outside of skull
Meningocele
Herniation of the cranial or spinal meninges bc of open cranial or spinal defect
The posterior frontal is referred to as ?
Lambda
arachnoid granulations
Nodular structures located along falx cerebri that reabsorb cerebrospinal fluid into venous system
Describe communicating hydrocephalus
Obstruction lies outside the ventricular system
What is the most common cranial abnormality?
Ventriculomegaly lat vents measure >10mm
Holoprosencephaly
a group of brain abnormalities consisting of varying degrees of fusion of the lateral ventricles, absence of the midline structures, and associated facial anomalies
choroid plexus produces?
cerebrospinal fluid
Falx cerebri separates what?
two cerebral hemispheres
Anophthalmia
Absence of eyes
What is the most severe form of holoprosencephaly?
Alobar
Dolichocephaly head shape assoc anomaly
Craniosynostosis
A cephalic index of less than 75 denotes?
Dolichocephalic shale
Gastroschisis
Herniation of abdominal contents through a RIGHT SIDED PERIUMBILICAL ABDOMINAL WALL DEFECT
Dolichocephalic head shape aka scaphocephaly is?
Narrow elongated head
The cerebellum tonsils become distorted with?
Spina bifida, Arnold Chiari malformation
The germinal matrix is a group of thin walled pressure sensitive vessels located within :
Subependymal layer of the ventricles
What is the most common cause of hydrocephalus in utero?
aqueductal stenosis
What does the falx cerebri separate?
cerebral hemispheres
The thalamus should not be confused with ?
cerebral peduncles which are more inferiorly positioned in the brain.
Cebocephaly
close-set eyes (hypotelorism) and a nose with a single nostril
Cloverleaf Head Shape: Associated Anomalies
thanatophoric dysplasia
What is the most common lethal skeletal dysplasia ?
thanatophoric dysplasia characterized by cloverleaf skull w frontal bossing and hydrocephalus
Glomus
the largest part of the choroid plexus
foramen magnum
the opening at the base of the skull through which the spinal cord passes from the brain
Cerebellar vermis
the portion of the cerebellum, located within the midline of the brain, that connects its two hemispheres
Lissencephaly
"Smooth brain"; condition where there is little to no gyri within cerebral cortex
Brachycephaly Head Shape: Associated Anomalies
*Craniosynostosis *Trisomy 21 *Trisomy 18
How many cerebral lobes are there ?
6- one frontal, two temporal lobes, two parietal lobes, and occipital lobe
Porencephaly
A cyst most often caused by intraparenchymal hemorrhage communicates w a lateral ventricle
Arnold-Chiari malformation
A group of cranial abnormalities assoc w spina bifida
*WITH BOTH SEVERE VENTRICULOMEGALY AND HOLOPROSENCEPHALY THERE WILL TYPICALLY BE?
A rim of cerebral tissue maintained
Acrania is?
Absence of the cranial vault above the bony orbits
Sono findings for Acrania/ Anencephaly
Absent cranial vault Some cerebral tissue may be present Frog like bulging eyes
What is the most common neural tube defect ?
Acrania
The "sunburst" of the cerebral sulk is a sonographic finding of:
Agenesis of the corpus callosum
corpus callosum connects the cerebral hemispheres and ?
Allows communication between the two lobes
What is the most severe form of holopronsencephaly ? And results in neonatal death
Alobar
Sono findings for Vein of Galen Aneurysm
Anechoic mass within midline of brain that has TURBULENT ARTERIAL AND VENOUS FLOW w color and pulsed Doppler Fetal hydrops Cardiomegaly
What are the most common neural tube defects occurring in 1 per 1,000 pregnancies?
Anencephaly and Spina bifida
The fourth ventricle is located:t
Anterior to the cerebellum within midline
What genetic disorder includes craniosynostosis, midline facial hypoplasia, and syndactlyly?
Apert dyn
What genetic disorder that includes craniosynostosis, midline facial hypoplasia, and syndactyly?
Apert syndrome
The third ventricle communicates with the fourth ventricle at the
Aqueduct of Sylvius
The third ventricle communicates w the fourth ventricle at the ?
Aqueduct of sylvius
What is responsible for the reabsorption of CSF into the venous system ?
Arachnoid granulations aka arachnoid villi
A cisterna magna less than 2mm is consistent with?
Arnold chiara ll malformation
Arachnoid cyts
Benign cyst that within brain rat hat do not communicate with ventricular system
Encephalomeningocele
Both meninges and brain tissue
A cephalic index more than 85 denotes ?
Brachiocephalic shape
Holopronsencephaly is a midline brain anomaly that is assoc w ?
Brain aberrations but also atypical facial structures
encephalocele
Brain tissue only
The anterior frontal when completely filled w bone is referred to as ?
Bregma
Enlargement of the frontal horns and narrowing of the occipital horns is?
COLPOCEPHALY
Choroid plexus is responsible for producing?
CSF CEREBRAL SPINAL FLUID
What is also typically absent w agensis of the corpus callosum?
CSP
The sono intracranial findings consistent w intrauterine infections are?
Calcifications around the ventriculomegaly and ventricles
What structure is located between the two lobes of the cerebellum
Cerebellum vermis
Mesencephalon turns into ?
Cerebral peduncles quadrigeminal plate and cerebral aqueduct
A lemon head shape is associated with what anomaly?
Chiara ll malformation
What should be suspected if cisterna magna is not visualized?
Chiari ll malformation
Enlargement of the frontal horns and narrowing of the occipital horn is :
Colpocephaly
What condition describes frontal horns small and occipital horns enlarged
Colpocephaly
corpus callosum functionally provides a pathway for?
Commutation between the hemispheres and is completely formed by 18 weeks
With dandy walker complex the cerebellar vermis is either ?
Completely absent or hypoplastic
With spina bifida the cerebellum being displaced makes the cisterna magna ?
Completely obliterated
Clinical findings of Vein of Galen Aneurysm (Neonatal)
Congestive heart failure
Then Vein of Galen Aneurysm is assoc w ?
Congestive heart failure in newborns
Choroid plexus cyst
Cyst located within the choroid plexus of the lateral ventricles
Dandy-Walker complex is a spectrum of Posterior fossa abnormalities that involve ?
Cystic dilation of the cisterna magna and fourth ventricle
Sono findings for Porencephaly
Cystic mass that communicates w lateral ventricles Mostly Unilateral
What cerebral malformation is as a result of agenesis or hypoplasia of the cerebellar vermis?
DWM
If cerebellar vermis is absent and fourth ventricle is enlarged then what must be suspected?
Dandy walker malformation
dura mater
Dense fibrous Outermost layer of the meninges
Schizencephaly is assoc w :
Development of fluid filled clefts within the cerebrum
The dense outermost layer of the menings is?
Dura matter
The sosmo findings of the dangling choroid sign describes ?
Echogenic choroid plexus, hanging limp, and surrounded by CSF within the dilated lateral ventricle
Trismoy 18 aka
Edwards syndrome
Clinical findings for Acrania/ Anencephaly
Elevated MSAFP
With spina bifida the frontal lobes become?
Flattened and will yield a lemon shape to the cranium referred to as lemon sign
Sono findings of Schizenecphaly
Fluid filled clefts within cerebrum Agensis of the CSP and corpus callusom 50% of the time Ventriculomegaly
Sono findings for hydraencephaly
Fluid filled cranium Absent or partial absence of falx cerebri Maintained brain stem, basal ganaglia, and perhaps the thalamus No identifiable cerebral cortex
With what structure does the posterior fossa cyst assoc w DWM communicates?
Fourth ventricle
Most often the origin of intracranial hemorrhage aka intraventricular hemorrhage is within ?
Germinal matrix
What is the most accurate measurement for estimating gestational age?
HC
The normal cerebral circulation yields a ?
High impedance Doppler w continuous forward flow throughout cardiac cycle
What cerebral abnormality are atypical facial features most commonly associated with?
Holoprosencephaly
sono finding With alobar holopronsencephaly
Horseshoe shaped mono ventricle Normal cerebellum and brain stem Fused echogenic thalami
What would most likely be the fetal cranial finding w TORCH infections?
Intracranial calcifications
What happens to the cerebellum in the presence of spina bifida?
It will become displaced inferiorly and posteriorly and appear curved referred to as Banana sign
Sono findings of Ventriculomegaly ?
Lateral ventricle measures >10mm Atrial measurement >15mm Dangling choroid sign Dilation of any part of the ventricular system
Sono findings for Arnold Chiari ll malformation
Lemon sign- Flattened frontal bone Banana sign Obliterated cisterna magna Colpocephaly Enlarged massa intermedia Hydrocephalus Open spinal defect
What is the least severe form of holoprosencephly?
Lobar
What may be confused w dandy walker complex ?
Mega cisterna magna
A measurement of more than 10mm of cisterna magna is consistent with?
Mega cisterna magna and Dandy walker complex
Meningocele
Meninges ONLY
Encephalomeningocystocele
Meninges, brain tissue, & lateral ventricle
With lobar holopronsencephaly infants may experience severe ?
Mental retardation
Normal head shape is
Mesocephaly
What artery has been shown effective at evaluating for potential hypoexia in fetuses that are small for dates?
Middle cerebral artery MCA
With hydraencephaly there is ?
NO CEREBRAL MANTEL PRESENT
Elevated levels of AFP are found with?
Omphalcoele, gastroschisis, multiple gestations, fetal demise, incorrect gestational dating
Sono findings for Cephaloceles
Open cranial defect- typically posterior Small or obliterated cisterna magna Complex or simple appearing mass protruding from cranium
With alobar holopronsencephaly the cortex can take on three basic shapes?
Pancake, cup or ball
Sono findings of agensis of CSP corpus callosum
Partial or complete absence of corpus callosum and CSP after 18 weeks Sunburst sign- radial arrangement of the sulci which produces spoke wheel pattern *COLPOCEPHALY- SMALL FRONTAL HORNS ENLARGED OCCIPITAL HORNS Elevated and dilated third ventricle
With hydraencephaly the falx cerebri may be ?
Partially or completely absent where as brain stem and basal ganglia are marinated and surrounded by CSF
Trismoy 13 aka
Patau syndrome assoc w holoprosecephaly
What chromosomal aberration is most often associated w holopronsencephaly?
Patu syndrome 13
With agensis of the corpus callosum the sulic tend to have a more ?
Perpendicular or radial arrangement spoke wheel pattern
What is the inner most layer of menings?
Pia matter
Following an intracranial hemorrhage a cyst is noted within the cerebrum that communicates with the lateral ventricles this is:
Porencephaly
Craniosynostosis
Premature closure of cranial sutures with subsequent fusion of cranial bones
What are Cephaloceles?
Protrusions of intracranial contents through a defect in the skull
Describe porencephaly
Rare condition in which a cyst communicates w the ventricular system
Arachnoid granulations/ arachnoid villi are responsible for ?
Reabsorption of CSF into venous system
Brachycephalic head shape is one that is considered?
Round, short and wide
The development of fluid-filled cleft within the cerebrum is consistent with:
Schizencephaly
Important sono finding of AGENIS OF THE CORPUS CALLUSOM AND CSP
Sunburst sign - radial arrangement of the sulci which produces a spoke wheel pattern
The most common intracranial tumor found in utero is?
Teratoma
What are the six cerebral lobes?
The frontal lobe, two temporal lobes, two parietal lobes, and the occipital lobe
Non-communicating hydrocephalus
The obstruction level is located within the ventricular system
The foremen magnum is:
The opening in the base of the cranium through which spinal cord travels
Teratomas contain?
Tissues such as hair, sebum, fat most often appear as complex masses that distort the normal architecture of the brain
What chromosomal abnormalities is asssoc w holopronsencephaly?
Trismoy 13 Patau
What syndrome is assoc w 50-70% of holopronsencephaly?
Trismoy 13 Patau syndrome
Choroid plexus cyst often regress although there is an asssoc w?
Trismoy 18 EDWARDS SYNDROME
Strawberry shaped skull is assoc w ?
Trismoy 18 Edwards syndrome
The choroid plexus cyst is assoc w ;
Trismoy 18 Edwards syndrome
Strawberry head shape is associated with?
Trisomy 18
Strawberry Head Shape: Associated Anomalies
Trisomy 18 (Edwards syndrome)
The CSP does not communicate with?
Ventricular system
dangling choroid sign is assoc w
Ventriculomegaly
Trismoy 8 aka
Warkany syndrome 2
Arachnoid cysts can be confused w Porencephaly but it is important to know that arachnoid cyst ____
Will NOT communicate w the ventricular system
Where is the most common location of spina bifida ?
Within the distal lumbosacral region
Dandy-Walker complex
a spectrum of posterior fossa abnormalities that involve the cystic dilatation of the cisterna magna and fourth ventricle
The fourth ventricle is located
anterior to the cerebellar vermis
Most common cause of hydrocephalus in utero is
aqueductal stenosis
The middle layer of the meninges is called the __________.
arachnoid mater
The third ventricle is located :
between the two lobes of the thalamus
The third ventricle is located?
between the two lobes of the thalamus
The anechoic midline brain structure located between the frontal horns and the lateral ventricles is the:
cavum septum pellucidum
Hypotelorism
condition in which the orbits are close together
What does the corpus callosum do?
connects cerebral hemispheres and allows communication between the two lobes
hydrocephalus
dilation of cerebral ventricles accompanied by the accumulation of cerebrospinal fluid within the skull
Dolichocephaly
elongated, narrow head shape aka scaphocephaly
Gyri
folds in the cerebral cortex
Cyclopia
fusion of the orbits
Apert Syndrome
genetic disorder that includes craniosynostosis, midline facial hypoplasia, and syndactyly
The resistance pattern of the MCA should be lesser or greater than that of umbilical artery?
greater
hypoplasia
incomplete development
The third ventricle connects to the fourth ventricle:
inferiorly by aqueduct of sylvius
Hypoxia
lack of oxygen in blood
What is located on both sides of the midline ?
lateral ventricles
A normal shaped skull is termed:
mesocephaly
arachnoid membrane
middle layer of the meninges
The most common location for a Cephalocele?
occipital region
cerebral peduncles
paired structures located anterior to the cerebral aqueduct
Inner most layer of meninges
pia mater
interhemispheric fissure
separates the two cerebral hemispheres
Lissencephaly
smooth brain
Vein of Galen Aneurysm
-A arteriovenous malformation that occurs within the fetal brain and is associated with congestive heart failure
The MCA/ umbilical artery resistive index is normally above __ whereas an index lower is considered abnormal
1.0
OFD can also be added to the BPD and multiplied by ?
1.62 obtain the HC
The depth of the cisterna magna should not measure greater than: or less than in a transcerebellar plane ?
10 mm 2mm
The cisterna magna should not exceed ___ in transcerebellar plane ?
10mm
corpus callosum forms later in gestation but should be completely intact between?
18 - 20 wks
The cerebellum grows at ?
1mm per week between 14 and 21 weeks
Alobar holopronsencephaly is diagnosed when there is an absence of ?
Corpus callusom, CSP, third ventricle, interhemispheric fissure, and falx cerebri
Two of the most disturbing findings w holopronsencephaly?
Cyclopia: orbits are fused contain a single eye Proboscis: false nose situated above the orbits
Hydraencephaly
FATAL condition in which the entire cerebrum is replaced by a large sac containing cerebrospinal fluid
What is the double fold of dura matter that divides the cerebral hemispheres?
Falx cerebri
Hydranencephaly prognosis
Fatal
Hydrops
Fatal abnormal accumulation of fluid in at least TWO fetal body cavities
Hydraencephaly sono appearance
Fluid filled cranium with absence of cerebral tissue
AFP exists the fetus through an opening in the neural tube if one is present allowing ?
For greater amount to be passed into maternal circulation
What is the largest part of the brain?
cerebrum
What fetal suture is located within the frontal bone along the midline of the forehead?
metopic suture
brain stem consists of
midbrain, pons, medulla oblongata
Cloverleaf skull is Associated with
thanatophoric dysplasia
cisterna magna
the largest cistern in the skull; located in the posterior portion of the skull
The interthalamic adhesion (massa intermedia) passes through the?
third ventricle
The interthalamic adhesion massa intermedia passes through:
third ventricle