The Fetal Head and Brain - Penny

lissencephaly

"smooth brain" there are no sulci or gyri in the cerebral cortex

agenesis of the corpus callosum and CSP

"spoke wheel" pattern (sunburst sign)

corrected BPD

The OFD and BPD is shape corrected and equivalent to the HC, independent of the shape of the skull

porencephaly

a cyst communicated with the ventricular system, common after the fetus has experienced hemorrhage within one of both of the cerebral hemispheres

falx cerebri

a double fold of dura mater that is located within the inter hemispheric fissure which separates the cerebral hemispheres, echogenic linear formation coursing through the midline of the fetal brain

cerebellum

a dumbbell-shaped or figure eight-shaped structure noted in the posterior cranium of the fetus

proboscis

a false nose situated above the orbits, associated with holoprosencephaly

hydraencephaly

a fatal condition in which the entire cerebrum is replaced by a large sac of CSF, there is no cerebral cortex identified

Arnold-Chiari II Malformation

a group of cranial abnormalities associated with the NTD spina bifida.

brachiocephalic head

a head that is considered round or short and wide

cephalic index

a tool used for indicating the shape of the fetal head =BPD/OFD x 100 <75 denoted a dolichocephalic head >85 denoted a brachiocephalic head

cisterna magna

an anechoic fluid filled space posterior to the cerebellum , between the cerebellar vermis and the interior surface of the occipital bone

dolichocephalic head (scaphocephaly)

an elongated, narrow head shape

cave septum pellucidum

anechoic box shaped structure in the axial scan plane, does not communicate with the ventricular system and its absence is associated with multiple cerebral malformations including genesis of the corpus callosum

trisomy 18 ( edwards syndrome)

choroid plexus cysts often regress, although there is a slight association with:

Thanatophoric dysplasia

cloverleaf-skull

the ventricular system

composed of four ventricles who's purpose to to provide cushioning for the brain

corpus callosum

connects the cerebral hemispheres and allows communication between the two lobes, echogenic band of tissue within the midline of the brain.

thalamus

consist of two lobes located on either side of the third ventricle

Apert syndrome

craniosynostosis, midline facial hypoplasia, and syndactyly

arachnoid cysts

cysts that do not communicate with the ventricular system

hydrocephalus

dilatation of the ventricular system caused by increased volume of CSF

MSAFP

elevated ___ is associated with anencephaly

Dandy- Walker malformation

enlarged cisterna magna >10mm, the cerebellar vermis is absent and the 4th ventricle is enlarged

ventriculomegaly

enlargement of the lateral ventricle beyond 10mm

schizencephaly

fluid filled clefts within the cerebrum agenesis od che CSP and corpus callosum (50% of the time) ventriculomegaly

lateral ventricles

house the choroid plexus

AFP

lab value found in association with neural tube defects by exiting the fetus through the opening in the neural tube and allowing for a greater amount to pass into the maternal circulation

spina bifida

may result in a mass that protrudes from the spine meningocele- herniation of the meninges myelomeningocele - herniation of meninges and spinal cord

Arnold-Chiari II malformation

measurement of the cisterna magna less than 2mm is consistent with

mega cisterna magna and Dandy-Walker complex

measurement of the cisterna magna more than 10mm is consistent with

choroid plexus

mostly located within the atria of the lateral ventricles, is responsible for producing CSF

mesocephalic

normal to medium sized skull

occipitofrontal diameter

obtained at the same level as the BPD and HC, one caliper id placed in the anterior midline in the middle of the frontal bone and the other is placed in the middle of the occipital bone

biparietal diameter

obtained in the avail plane at the level of the CSP, thalmus, and falx, This is the same level as the third ventricle, which may be seen between the two lobes of the thalmus

cyclopia

orbits are fused and contain a single eye, associated with holoprosencephaly

craniosynostosis

premature fusion of the sutures: flexible structures that connect the cranial bones which remain slightly mobile until delivery to facilitate the passage of the skull through the birth canal

Trisomy 13 (patau syndrome)

present in 50-70% of fetuses diagnosed with holoprosencephaly

cephaloceles

protrusions of intracranial contents through a defect in the skull, the most common location is in the occipital region, possible elevation of MSAFP

Lemon sign - lemon shaped head Banana sign - banana shaped cerebellum obliterated cisterna magna

signs associated with Arnold-Chiari II Malformation

colpocephaly

small frontal horns and enlarged occipital horns (teardrop shaped lateral ventricles) associated with ageneiss of the corpus callosum and CSP, and arnold-chiari II

fontanelles or "soft spots"

spaces that exist between the forming fetal bones that are used as sonographic windows during neurosonographic exams on newborns

trisomy 18 (edwards syndrome)

strawberry shaped skull

head circumference

taken at the same time and same level of the cranium as the BPD, a measurement around the entire cranium

between the two lobes of the thalmus

the 3rd ventricle is located:

anterior to the cerebellar vermis

the 4th ventricle is located:

acrania

the absence of the cranial vault above the bony orbits

metopic suture

the fetal suture located within the frontal bone along the midline of the forehead

third ventricle

the inter thalamic adhesion (mass intermedia) passes through the

cerebrum

the largest part of the brain

HC

the most accurate measurement for estimating gestional age is

aqueductal stenosis

the most common cause of hydrocephalus in utero

teratoma

the most common intracranial tumor found in utero is the

alobar holoprosencephaly

the most severe form, often resulting in neonatal death, the cortex can take on three shapes resembling a "pancake", "cup", or "ball" there will be evidence of a horseshoe-shaped monoventricle, and the lobes of the thalmus may be fused and echogenic in appearance

10mm

the normal lateral ventricle does not measure more than _____ a the level of the atrium

foramen magnum

the opening at the base of the cranium through which the spinal cord travels

ventriculomegaly

the sonographic finding of the "dangling choroid" sign describes and echogenic choroid plexus, hanging limp, and surrounded by CSF, this finding is exceedingly specific for:

calcifications around the ventricles and ventriculomegaly

the sonographic intracranial findings consistent with intrauterine infections are___

aqueduct of Sylvius or the cerebral aqueduct

the third ventricle connects to the fourth ventricle inferiorly by means of a long, tubelike structure called:

cerebrum and cerebellum

the two main parts of the brain

exencephaly

type of acrania when a normal amount of cerebral tissue is present

anencephaly

type of acrania when there is no cerebral hemispheres present

holoprosencephaly

what cerebral abnormality are atypical facial features most commonly associated with

the resistance pattern of the MCA should be greater than that of the umbilical artery

when fetal shunting is suspected the sonographer should look at the ___

communicating hydrocephalus

when the obstruction causing excess CSF lies outside of the ventricular system

noncommunicating hydrocephalus

when the obstruction causing excess CSF lies within the ventricular system

fourth ventricle

with what structure does the posterior fossa cyst associated with DWM communicate