Fetal Central Nervous System Part 2 Flashcards Preview

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Flashcards in Fetal Central Nervous System Part 2 Deck (42):

An intracranial abnormality that is dilation of the ventricular system, because of an increase in CSF. It may indicate a blockage somewhere. This abnormality is called when the transverse dimension of the ventricular atrium exceeds 10mm.



What are the three classifications of hydrocephalus?

1. Obstructive or non communicating
2. Communicating
3. Idiopathic (unknown cause)


Which classification of hydrocephalus is caused by obstruction of CSF flow due to Aqueductal Stenosis, a cerebral abnormality like spina bifida, or tumor.

Obstructive or non communicating


Which classification of hydrocephalus is a dilation of all ventricles and the subarachnoid space caused by an obstruction of CSF flow outside of the ventricular system, usually caused by a faulty absorption of CSF or increase CSF production.



What is seen sonographically with ventriculomegaly/hydrocephalus?

- normal ventricular configuration with ventricular size greater than 10mm
- Sometimes choroid plexus, dangling within the enlarged ventricular system
- Associated findings include polyhydraminos, meningomyelocele, encephalocele, intracranial tumor, Dandy-Walker malformation.


If there is a brain abnormality, the fetus will not swallow the fluid normally and the result is _____________.



This is a whole spectrum of disorders resulting from absent or incomplete division of the forebrain (prosencephalon) into the cerebral hemispheres and lateral ventricles.



____________ can be sporadic, due to chromosomal abnormailities (especially Trisomy 13) or maternal infection



What does "the face predicts the brain" mean?

The more severe the facial abnormality, the more severe the intracranial or brain abnormality.


Facial anomalies may range from __________ (one single orbit) with a proboscis (a large structure that looks like a nose), to __________ (close-set eyes) to facial clefts.



What are the 3 types of Holoprosencephaly?

1. Alobar holoprosencephaly
2. Semi-lobar holoprosencephaly
3. Lobar holoprosencephaly


Which type of holoprosencephaly is described below:
- more severe form
- monoventricle
- fused thalami
- absence of the falx

Alobar holoprosencephaly


Which type of holoprosencephaly is described below:
- partial separation of ventricles and hemispheres with occipital lobe present
- incompletely fused thalami

Semi-lobar holoprosencephaly


Which type of holoprosencephaly is described below:
- least severe form
- normal separation of the paired thalami, hemispheres and ventricles
- cavum septum pellucidum will be absent **
- also absence of the olfactory tracks (we never see these on ultrasound)

Lobar holoprosencephaly


A destructive disorder due to bilateral internal carotid artery occlusion or malformation in fetal life. The cerebral hemispheres will not form but have in tact and normally developed skull and meninges or coverings of the brain. (a giant water head with no cortex)



***The key difference between hydranencephaly and holoprosencephaly is that the _______ _______ is intact.

falx cerebri


Sonographic findings for ___________ include: large fluid filled cranium, intact falx, normal midbrain and basal ganglia. Therefore the paired thalami are intact. Polyhyramnios will also be present.



What is the key difference between hydranencephaly and massive hydrocephalus?

With massive hydrocephalus there will be a thin rim of cortex remaining.


A complete or partial absence of the cerebellar vermis and posterior fossa cystic dilation of the fourth ventricle.

Dandy-Walker malformation


The ______ ______ is the midline portion of the cerebellum which is the center for all balance in human beings.

cerebellar vermis


80% of fetuses with dandy-walker malformation have _________.



What malformation is associated with autosomal recessive syndromes, maternal infection, maternal diabetes, and exposure to alcohol and coumadin.

Dandy-Walker malformation


What are the sonographic findings of Dandy-walker malformation?

- complete or partial agenesis of the midline cerebellar vermis with flattened cerebellar hemispheres
- large midline cystic structure in the posterior fossa
- large ventricles, greater than 10mm
- polyhydramnios
- differentiated from subarachnoid cyst by contiguity with 4th ventricle


Development of the corpus callosum should be complete by ____ weeks of gestation.



________ occurs in 1-3 per 1000 live births and it's due to a chromosomal abnormality or chromosomal translocation. It is frequently associated with other anomalies and syndromes.

Agenesis of Corpus Callosum


Of these sonographic findings for Agenesis of Corpus callosum which is the main point?
- Absent cavum septum pellucidum
- elevated and enlarged third ventricle
- widely seperated frontal horns of the lateral ventricles with enlarged occipital horns
- teardrop shaped ventricles, displaced upward and outward (called colpocephaly)

absent cavum septum pellucidum


A rare arteriovenous malformation which causes increased blood flow through the vein of galen. Sonographically, there is a well-defined midline vascular structure superior and posterior to the thalamus with turbulent blood flow within.

Vein of Galen Aneurysm


What are choroid plexus cysts? When is a follow up recommended?

Small cyst within the choroid plexus and are very common. They can be unilateral or bilateral, multiple or single, and large or small. Without associated abnormalities, these can be considered normal variant. Follow up is recommended if a cyst is found in a patient that has not had prior genetic workup.


With Choroid plexus cysts there is an infrequent association with _________.

trisomy 18


Congenital brain tumors are very rare. Teratoma's are the most common lesions but other tumor types include germinomas, epidermoids, glioblastomas, and craniopharyngiomas. Prognosis is terrible.
This all describes what?

Intracranial tumors


What will you see sonographically in Intracranial tumors?

a space occupying lesions or a mass which changes the normal anatomic structures.


A condition where the brain lacks normal sulci and gyri, and therefore appears smooth.This diagnosis cannot be made until 3rd trimester and is usually associated with enlarged ventricles and possibly an abnormal corpus callosum.


**most important is brain appears smooth (no bumps)


A rare malformation which is characterized by a large, open cleft in the cerebral hemisphere in the region of the primary fissures. The clefts are usually bilateral and symmetric, but not always. The brain appears "split" into anterior and posterior parts.



The presence of cystic areas within the brain parenchyma itself. The cysts can vary in size and location and may communicate with the cerebral ventricles. This is thought to be caused by intracranial hemorrhage or encephalomalacia.



_____________ is defined as decreased head size, more than 3 standard deviations below the mean. This is a symptom of several causative factors. Causes include craniosynostosis (abnormal fusion of the cranial structures), chromosomal abnormalities, and exposure to teratogens.



What is a rare tumor which arises from embryonic cells of the sacrum and coccyx? These may be external, intrapelvic, and/or intra-abdominal.

Sacrococcygeal teratoma


What are the three grades of sacrococcygeal teratoma?

1. Benign or mature
2. Immature
3. Malignant


Tumors are frequently very __________ and have both _________ and solid components.



What are the sonographic findings of a sacrococcygeal teratoma?

- a large complex mass
- Polyhydramnios
- Maternal increased alpha-fetoprotein levels


This syndrome includes a whole spectrum of skeletal abnormalities of the lower spine and lower limbs such as sacral agenesis, lumbar spine or even lower thoracic agenesis. There are also abnormalities of the G.I. and GU tracts, Cerebral and heart abnormalities.

Caudal Regression Syndrome


While most cases are sporadic, up to _______ of Caudal Regression Syndrome cases are associated with ________ _________.

16%; diabetes mellitus


An abnormal curvature of the spine, possibly involving any segment of the spine but most frequently the thoracolumbar region. Association with structrrual defects, most commonly CNS and VATER. Severe curves are associated with lethal abnormalities such as anencephaly, limb-body wall complex, and amniotic band syndrome.

Scoliosis and Kyphosis