Ch. Fetal Central Nervous System

Question 1

The neural tube should be closed by how many weeks?

Answer 1

6 menstrual weeks

Question 2

Which imaging plane is best to detect spina bifida?

Answer 2

The transverse plane

Question 3

The sagittal and or coronal plane is used to assess what aspects of the spine?

Answer 3

Cervical and lumbosacral curvatures
sacral caudal tapering
configuration of vertebral ossification centers

Question 3

The sagittal and or coronal plane is used to assess what aspects of the spine?

Answer 3

Cervical and lumbosacral curvatures
sacral caudal tapering
configuration of vertebral ossification centers

Question 4

What is the normal limit of the lateral ventricles throughout all of the gestational age?

Answer 4

<10 mm

Question 5

What is the normal range of measurements for the cisterna magna throughout all of gestational age?

Answer 5

> 3mm and <10mm

Question 6

What kind of defects occur when there is a failure of the neural tube to completely close by 6 weeks?

Answer 6

Neural tube defects (NTDs)

Question 7

What is known to decrease a patient’s risk of NTDs?

Answer 7

Folic acid

Question 8

The most common NTD, occurring more common in females and multiple gestations, it is the congenital absence of the cerebral hemispheres and cranial vault

Answer 8

Anencephaly

Question 9

Sonographic appearance of anencephaly

Answer 9

“Frog face” sign
absence of the cerebral hemispheres and cranial vault
face and orbits are present
fetal cranium should be present by 12 weeks (15 weeks at the latest)
POLYHYDRAMNIOS (due to ineffective swallowing)

Question 10

Developmental abnormality in which the cranium is partially or completely absent with the development of abnormal brain tissue, will have elevated levels of MSAFP.

Answer 10

Acrania aka exencephaly

Question 11

Sono finds of acrania/ exencephaly

Answer 11

Break in the skull with the presence of large amount of brain tissue
reliably demonstrated by 16 weeks as lack of ossified cranium

Question 12

The herniation of brain and meninges or meninges and CSF (meningocele) through a cranial defect

Answer 12

Encephalocele aka Cephalocele

Question 13

Where are encephaloceles usually located

Answer 13

Midline, most commonly occipital, may be frontal or lateral

Question 14

Encephaloceles are associated with what syndrome

Answer 14

Meckel-Gruber syndrome

Question 15

Sono finds of encephalocele

Answer 15

purely cystic extracranial mass (meningocele)
solid mass contiguous with the cranium (cephalocele)
often associated with hydrocephalus and polyhydramnios
Break in the skull??

Question 16

Term for lack of closure of the vertebral column, usually occurring in the lumbosacral region

Answer 16

Spina bifida

Question 17

Herniation of the meninges and CSF through a spinal defect

Answer 17

meningocele

Question 18

herniation of the meninges AND neural elements (spinal cord) through the spinal defect

Answer 18

Meningomyelocele

Question 19

Transverse sono finds of spina bifida

Answer 19

Splaying of the posterior elements into a “U” or “V” configuration
when sac is intact, cystic structure may be seen extending from the back

Question 20

Sagittal sono finds of spina bifida

Answer 20

Splaying of the parallel ossification centers
soft tissue defect or discontinuity or skin and muscle of posterior back
(be aware of normal widening of the spine in the cervical and lumbar regions)

Question 21

Associated findings in spina bifida are secondary to the —— (what syndrome or condition)

Answer 21

Arnold-Chiari II M=malformation

Question 22

Intracranial signs of spina bifida

Answer 22

“Lemon” sign - flattening of the temporal/frontal bones due to decreased intracranial pressure
“Banana” sign - obliteration of cisterna magna by abnormal configuration of the cerebellum
hydrocephalus - Lat vent > 10 mm

Question 23

Rare malformation in which the occiput is fused to the cervical region.

Answer 23

Iniencephaly

Question 24

Sono finds of Iniencephaly

Answer 24

occipital encephalocele cervical spina bifida marked head and neck hyperextension

Question 25

Associated intracranial findings in spina bifida are secondary to what malformation?

Answer 25

Arnold-Chiari II Malformation

Question 26

Describe the flow of CSF starting with the 1st and 2nd ventricles

Answer 26

1) lateral ventricles 2) Foramen of Monro aka Intraventricular foramen 3) Third ventricle 4) Aqueduct of Sylvius aka Cerebral Aqueduct 5) Fourth ventricle 6) fluid will drain into either the Foramen of Luschka or the Foramen of Magendie

Question 27

Dilatation of the ventricular system secondary to an increase in the volume of CSF OR the decrease in absorption

Answer 27

Ventriculomegaly aka Hydrocephalus

Question 28

What is the most common cause of OBSTRUCTIVE or NONCOMMUNICATING hydrocephalus?

Answer 28

Aqueductal stenosis

Question 29

Define communicating hydrocephalus

Answer 29

There is dilation of all ventricles and the subarachnoid space caused by faulty absorption of CSF or increased CSF production. NOT CAUSED BY AN OBSTRUCTION

Question 30

Describe sonographic findings of hydrocephalus

Answer 30

the presence of excess fluid in the lateral ventricles causing them to measure >10 mm "DANGLING" choroid plexus

Question 31

Measurements of ventriculomegaly/ hydrocephalus

Answer 31

Mild ventriculomegaly - 10-12 mm Moderate Ventriculomegaly - 12.1-15 mm Severe ventriculomegaly/ Hydrocephalus >15 mm

Question 32

A spectrum of disorders resulting from absent or incomplete diverticulation (division) of the prosencephalon (forebrain) into the cerebral hemispheres and lat vents

Answer 32

Holoprosencephaly

Question 33

Which trisomy is associated mostly with holoprosencephaly

Answer 33

Trisomy 13 aka Patau syndrome

Question 34

What type of facial anomalies are seen with holoprosencephaly

Answer 34

Cyclopsia (single orbit) Proboscis Hyportelorism Facial clefts

Question 35

Type of holopros that is the least severe, associated with normal separation of the thalami, hemispheres, and ventricles. There is an absent CSP and olfactory tracts

Answer 35

Lobar holoprosencephaly

Question 36

Type of holopros that is associated with partial separation of ventricles and hemispheres with occipital lobe present. There is an incomplete fused thalami

Answer 36

Semi-lobar holoprosencephaly

Question 37

The most severe form of holopros in which there is a MONOVENTRICLE, fused thalami, and absence of the falx cerebri

Answer 37

Alobar holoprosencephaly

Question 38

T or F, in the presence of holoprosencephaly, the cerebellum and posterior fossa will be normal

Answer 38

True. It is the prosencephalon (forebrain) that is affected by holopros, not the posterior portion of the brain

Question 39

CNS disorder that is characterized by near total lack of the cerebral hemispheres with intact and normally developed meninges and skull

Answer 39

Hydranencephaly

Question 40

What is hydranencephaly thought to be caused by

Answer 40

Bilateral internal carotid artery occlusion or malformation

Question 41

Sono finds of hydranencephaly

Answer 41

Macrocephaly absent cerebral tissue (cortical mantle) Falx cerebri is present Normal midbrain and basal ganglia Polyhydramnios

Question 42

CNS disorder that is defined as the complete or partial absence of the cerebellar vermis and posterior fossa cystic dilatation communicating with the 4th ventricle

Answer 42

Dandy walker malformation (DWM)

Question 43

List things that DWM has been associated with

Answer 43

Autosomal recessive syndromes maternal infection Diabetes exposure to alcohol

Question 44

Sono finds of dandy walker malformation

Answer 44

complete or partial agenesis of the vermis with flattened cerebellar hemispheres large midline cystic structure in posterior fossa associated with ventriculomegaly and poly diff from subarachnoid cysts by contiguity with 4th vent

Question 45

Development of the corpus callosum should be complete at

Answer 45

20 weeks

Question 46

Sono finds of agenesis of the corpus callosum

Answer 46

ABSENT CSP elevated dilated third ventricle "TEAR DROPPED" shaped ventricles Moosehead appearance on MRI

Question 47

Well defined cystic structure superior and posterior to the thalamus with turbulent and or arterial flow

Answer 47

Vein of Galen aneurysm

Question 48

Choroid plexus cysts are associated with which trisomy

Answer 48

Trisomy 18 aka Edwards syndrome

Question 49

What brain tumors are the most common

Answer 49

teratomas

Question 50

Condition in which the brain lacks sulci and gyri resulting in an overall smooth apperance

Answer 50

Lissencephaly

Question 51

Condition characterized by clefts in the cerebral hemispheres in the region of the primary fissures

Answer 51

Schizencephaly ( the brain will appear split into anterior and posterior parts)

Question 52

Simple cystic structures WITHIN brain parenchyma that communicate with the ventricular system

Answer 52

Porencephaly

Question 53

A rare tumor arising from the embryonic cells of the sacrum/coccyx, they may be external, intrapelvic, and or intra-abdominal

Answer 53

Sacrococcygeal teratoma

Question 54

Sono finds of sacrococcygeal teratomas

Answer 54

an internal or external complex large mass poly increased AFP possible hydrops fetalis

Question 55

What maternal condition is associated 16% with caudal regression syndrome

Answer 55

Diabetes mellitus

Question 56

What is caudal regression syndrome

Answer 56

Includes a spectrum of skeletal anomalies of the lower spine and lower limbs such as sacral agenesis, lumbar spine, or even lower thoracic agenesis. THE ABSENCE OF THE SPINE, it just stops forming

Question 57

Abnormal curvature of the spine may involve any segment but is most frequently found in which region

Answer 57

Thoracolumbar region