Fetal Central Nervous System Part 2

Question 1

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.

Answer 1

Ventriculomegaly/hydrocephalus

Question 2

What are the three classifications of hydrocephalus?

Answer 2

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

Question 3

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

Answer 3

Obstructive or non communicating

Question 4

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.

Answer 4

Communicating

Question 5

What is seen sonographically with ventriculomegaly/hydrocephalus?

Answer 5

• 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.

Question 6

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

Answer 6

polyhydramnios

Question 7

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

Answer 7

Holoprosencephaly

Question 8

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

Answer 8

Holoprosencephaly

Question 9

What does “the face predicts the brain” mean?

Answer 9

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

Question 10

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.

Answer 10

cyclopia

hypotelorism

Question 11

What are the 3 types of Holoprosencephaly?

Answer 11

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

Question 12

Which type of holoprosencephaly is described below:

• more severe form
• monoventricle
• fused thalami
• absence of the falx

Answer 12

Alobar holoprosencephaly

Question 13

Which type of holoprosencephaly is described below:

• partial separation of ventricles and hemispheres with occipital lobe present
• incompletely fused thalami

Answer 13

Semi-lobar holoprosencephaly

Question 14

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)

Answer 14

Lobar holoprosencephaly

Question 15

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)

Answer 15

Hydranencephaly

Question 16

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

Answer 16

falx cerebri

Question 17

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.

Answer 17

hydranencephaly

Question 18

What is the key difference between hydranencephaly and massive hydrocephalus?

Answer 18

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

Question 19

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

Answer 19

Dandy-Walker malformation

Question 20

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

Answer 20

cerebellar vermis

Question 21

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

Answer 21

hydrocephalus

Question 22

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

Answer 22

Dandy-Walker malformation

Question 23

What are the sonographic findings of Dandy-walker malformation?

Answer 23

• 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

Question 24

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

Answer 24

20

Question 25

________ 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.

Answer 25

Agenesis of Corpus Callosum

Question 26

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)

Answer 26

absent cavum septum pellucidum

Question 27

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.

Answer 27

Vein of Galen Aneurysm

Question 28

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

Answer 28

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.

Question 29

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

Answer 29

trisomy 18

Question 30

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?

Answer 30

Intracranial tumors

Question 31

What will you see sonographically in Intracranial tumors?

Answer 31

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

Question 32

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.

Answer 32

Lissencephaly

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

Question 33

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.

Answer 33

Schizencephaly

Question 34

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.

Answer 34

Porencephaly

Question 35

_____________ 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.

Answer 35

Microcephaly

Question 36

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

Answer 36

Sacrococcygeal teratoma

Question 37

What are the three grades of sacrococcygeal teratoma?

Answer 37

1. Benign or mature
2. Immature
3. Malignant

Question 38

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

Answer 38

vascular

cystic

Question 39

What are the sonographic findings of a sacrococcygeal teratoma?

Answer 39

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

Question 40

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.

Answer 40

Caudal Regression Syndrome

Question 41

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

Answer 41

16%; diabetes mellitus

Question 42

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.

Answer 42

Scoliosis and Kyphosis