2nd & 3rd Tri: Central Nervous System Flashcards
1
Q
When is the neural tube closed by?
A
6 menstrual weeks
pg. E 120
2
Q
What plane is best to evaluate for spina bifida?
A
transverse
pg E 120
3
Q
What should be shown in the trransverse plane of the spine?
A
location of ossification centers
musculature of back
skin line
pg. E 120
4
Q
What should be shown in the sagittal/coronal plane of the spine?
A
cervical and lumbosacral curvatures
sacral tapering
configuration of vertebral ossification centers
pg. E 120
5
Q
At what level is the BPD taken?
A
level of thalami, CSP, and anterior horns of lat ventricle
pg. E 121
6
Q
What is a normal measurement for the atrium of lateral ventricle?
A
< 10 mm
pg. E 121
7
Q
What fills in the lateral ventricles?
A
choroid plexus
pg. E 122
8
Q
What is taken at an axial section of the brain?
A
CSP thalami lateral ventricles choriod plexus BPD HC pg. E 121
9
Q
What is taken at an oblique axial section of the brain?
A
cerebellum
brain stem
cisterna magna
pg. E 123
10
Q
What is a normal measurement of the cisterna magna?
A
> 3 mm and < 10 mm
pg. E 123
11
Q
Why do neural tube defects occur?
A
when neural tube fails to close by 6 weeks
pg. E 124
12
Q
Where do neural tube defects occur at?
A
anywhere along cranium or spine
allow cerebrospinal fluid to escape into the amniotic fluid
pg. E 124
13
Q
What lab is elevated with neural tube defects?
A
MSAFP
pg. E 124
14
Q
Why would an amniocentesis be performed?
A
when MSAFP values are high and ultrasound did not detect a neural tube defect
pg. E 124
15
Q
What does an amniocentesis detect?
A
acetylcholinesterase is elevated in the amniotic fluid when there are neural tube defects
pg. E 124
16
Q
What can be done to decrease the risk of neural tube defects?
A
supplement folic acid
pg. E 124
17
Q
What is anencephaly?
A
congenital absence of the cerebral hemispheres and cranial vault
pg. E 124 O 390
18
Q
What is the most common neural tube defect?
A
Anencephaly
pg. O 390
19
Q
Why does anencephaly occur?
A
cephalic end of the neural tube fails to close by 24 days gestation
pg. E 124 O 390
20
Q
What is elevated with anencephaly?
A
AFP
pg. E 124 O 390
21
Q
What is associated with anencephaly?
A
polyhydramnios
spina bifida
pg. E 124
22
Q
What are the sonographic findings of anencephaly?
A
absent cranial vault and cerebral hemispheres
frog-like facial appearance
polyhydramnios
pg. E 124
23
Q
What is acrania?
A
cranium partially or completely absent with development of abnormal brain tissue
pg. E 125
24
Q
What is elevated with acrania?
A
MSAFP
pg. E 125
25
What are the sonographic findings of acrania?
presence of brain tissue as early as 12 weeks -16 weeks
lack of ossified cranium
pg. E 125
26
What is exencephaly?
acrania
| pg. E 125
27
What is an encephalocele?
herniation of brain and meninges or meninges and CSF through a cranial defect
pg. E 125 O 390
28
What syndrome is an encephalocele associated with?
Meckel-Gruber syndrome
| pg. E 125
29
Where are encephaloceles located?
midline
occipital (most common)
frontal or lateral
pg. E 125
30
What are the sonographic findings of encephalocele?
```
cystic extracranial mass (meningocele)
solid mass in cranium (cephalocele)
hydrocephalus
polyhydramnios
pg. E 125
```
31
What is another name for encephalocele?
cephalocele
| pg. E 125
32
What is spina bifida?
lack of closure of the vertebral column
| pg. E 126 O 390
33
Where is the most common place for spina bifida?
lumbosacral
| pg. E 126
34
What is a meningocele?
herniation of the meningese and CSF through a spinal defect
| pg. E 126
35
What is meningomyelocele?
herniation of the meninges and spinal cord through the spinal defect
pg. E 126
36
What are the transverse findings of spina bifida?
splaying of posterior elements into a U or V configuration
cystic structure extending from back
pg. E 126
37
What are the sagittal findings of spina bifida?
splaying of parallel ossification centers
soft tissue defect
pg. E 126
38
What are some intracranial findings associated with spina bifida?
"lemon sign" - head shape
"banana sign" - cerebellum shape
hydrocephalus
pg. E 127
39
What is associated with spina bifida?
Arnold-Chiari II malformation
| pg. E 127
40
What is spina bifida aperta?
defect exposed completely
elevated AFP level
associated w/ cleft lip, cardiac defects, encephalocele, GI anomalies, and clubfoot
pg. O 390
41
What is spina bifida occulta?
defect is covered by soft tissue
normal AFP level
not as easily diagnosed w/ US
pg. O 390
42
What is iniencephaly?
rare malformation where the occiput is fused to the cervical spine
pg. E 127
43
What are the sonographic findings of iniencephaly?
hyperextended neck and head
occipital encephalocele/cervical spina bifida
pg. E 127
44
How does cerebrospinal fluid flow through the ventricles?
lateral ventricles -->3rd ventricle --> 4th ventricle
| pg. E 128
45
What is ventriculomegaly?
dilatation of the ventricular system due to increase in volume of CSF
pg. E 128
46
When is ventriculomegaly considered hydrocephalus?
head enlarges and CSF spreads
can cause brain damage
pg. E 128
47
What is obstructive hydrocephalus?
aka non-communicating;
obstruction of CSF flow due to aqueductal stenosis, CNS anomaly, or tumor
E 129
48
What is aqueductal stenosis?
narrowing of the aqueduct of Sylvius due to inflammation or developmental process
pg. E 129
49
What is communicating hydrocephalus?
dilatation of all ventricles and subarachnoid space caused by an obstruction to CSF flow outside of the ventricular system
pg. E 129
50
What are the sonographic findings of hydrocephalus?
dilated ventricles > 10mm
dangling choroid plexus
brain echogenicity
pg. E 129
51
What are some other associated findings with hydrocephaly?
```
polyhydramnios
abnormal fetal lie
fetal ascites
hepatomegaly
meningomyelocele
Dandy Walker Malformation
encephalocele
intracranial tumor
pg. E 129
```
52
What is holoprosencephaly?
absent or incomplete division of the forebrain (prosencephalon) into the cerebral hemispheres and lateral ventricles
pg. E 130
53
What are the types of holoprosencephaly?
alobar
semi-lobar
lobar
pg. E 130
54
What is the most severe form of holoprosencephaly?
Alobar
| pg. E 130
55
What are the sonographic findings of alobar holoprosencephaly?
1 ventricle
fused thalami
absence of falx cerebri
pg. E 130
56
What are the sonographic findings of semi-lobar holoprosencephaly?
partial separation of the ventricles and hemispheres
occipital lobe present
incompletely fused thalami
pg. E 130
57
What are the sonographic findings of lobar holoprosencephaly?
least severe
normal separation of the thalami, hemispheres, and ventricles
absent CSP and olfactory tracts
pg. E 130
58
What reasons can holoprosencephaly be caused by?
Sporadic - chromosomal abnormalities
maternal infection
pg. E 130
59
What are some associated findings with holoprosencephaly?
facial anomalies- cyclopia w/ proboscis
hypotelorism
facial clefts
pg. E 130
60
What is hydranencephaly caused by?
ICA occlusion or malformation
| pg. E 131
61
What is hydranencephaly?
near total lack of cerebral hemispheres with normally developed meninges and skull
brain is replaced w/ CSF
pg. E 131 O 389
62
What anomalies are associated with hydranencephaly?
no associated anomalies or risk
| pg. E 131
63
What are the sonographic findings of hydranencephaly?
```
macrocephaly
fluid filled cranium
absent cerebral tissue
necrosis
polyhydramnios
pg. E 131
```
64
What is Dandy-Walker Malformation (DWM)?
complete or partial absence of cerebellar vermis and posterior fossa cystic dilatation
pg. E 131 O 389
65
What can cause DWM?
```
autosomal recessive syndromes
maternal infection
diabetes
alcohol use
Coumadin use
pg. E 131 O 389
```
66
What are the sonographic findings of DWM?
```
enlarged posterior fossa
complete or partial agenesis of the cerebellar vermis
cisterna magna > 1.0 cm
ventriculomegaly
polyhydramnios
pg. E 131 O 389
```
67
What do 80% of DWM fetuses have?
hydrocephalus
| pg. E 131
68
When should the corpus callosum be developed by?
20 weeks
| pg. E 132
69
Why does the corpus callosum not develop?
chromosomal abnormality or translocation
failure of callosal fibers to form
pg. E 132
70
What are the sonographic findings of agenesis of the corpus callosum?
```
no CSP
dilatation of the 3rd ventricle
widely separated frontal horns of lateral ventricles with enlarged occipital horn
teardrop shaped ventricles
Colpocephaly
"Sunburst sign"
pg. E 132 O 388
```
71
What is a vein of Galen aneurysm?
rare arteriovenous malformation causing increased flow through the vein of Galen.
pg. E 132
72
What are the songoraphic findings of a vein of Galen aneurysm?
midline vascular structure superior and posterior to thalamus with turbulent arterial flow
pg. E 132
73
What is a choroid plexus cyst?
```
unilateral or bilateral
single or multiple
large or small
cysts in ventricle
pg. E 133
```
74
Are choroid plexus cysts common?
yes
| pg. E 133
75
Are choroid plexus cysts associated with other anomalies?
normally isolated finding, but can be associated with aneuploidy (Trisomy 18 specifically)
pg. E 133
76
What would be the most common intracranial lesion?
teratomas
| pg. E 133
77
What is lissencephaly?
brain lacks sulci and gyri, which make the brain appear smooth
pg. E 133
78
What is lissencephaly associated with?
ventriculomegaly
abnormal corpus callosum
pg. E 133
79
When can lissencephaly be diagnosed?
3rd trimester
| pg. E 133
80
What is schizencephaly?
rare malformation with clefts in the cerebral hemispheres
| pg. E 134
81
What is the sonographic appearance of schizencephaly?
typically bilateral and symmetric
brain appears split into anterior/posterior parts
pg. E 134
82
What is porencephaly?
presence of cysts within the cerebral parenchyma due to intracranial hemorrhage
pg. E 134
83
What is the sonographic appearance of porencephaly?
simple cystic structures within cerebral parenchyma
| pg. E 134
84
What is microcephaly?
```
decreased head size (3 SD below mean)
due to several etiologic disturbances:
chromosomal
craniosynostosis
teratogens
pg. E 134
```
85
What is a sacrococcygeal teratoma?
rare tumor arising from the embryonic cells of the sacrum/coccyx
pg. E 135
86
What are the sonographic findings of sacrococcygeal teratomas?
```
large complex mass
external or internal
polyhydramnios
hydrops fetalis
increased AFP
pg. E 135
```
87
What is caudal regression syndrome?
spectrum of skeletal anomalies of the caudal end of the neural tube
pg. E 135 O 390
88
What is caudal regression syndrome associated with?
diabetes mellitus
sporadic
pg. E 135 O 390
89
What anomalies are associated with caudal regression syndrome?
```
sacral, lumbar or thoracic agenesis
GI tract
GU tract
CNS
heart
pg. E 135
```
90
What is scoliosis?
abnormal curvature of spine
| pg. E 135
91
What are the possibilities if the skull is not present?
anencephaly
acrania (exencephaly)
pg. E 136
92
What are the possibilities if the skull is not intact?
encephalocele
Meckel-Gruber
pg. E 136
93
What are the possibities if there is no falx cerebri present?
holoprosencephaly
| pg. E 136
94
What are the possibilities if the thalami are not separate?
holoprosencephaly
| pg. E 136
95
What are the possibilities if the lateral ventricles measure > 10 mm?
```
ventriculomegaly
hydrocephalus
Spina bifida
DWM
pg. E 136
```
96
What are the possibilities if the choroid plexus is not identified or normal?
hydranencephaly
choroid plexus cyst
Trisomy 18
pg. E 136
97
What settings should you use to evaluate for a vein of Galen aneurysm?
color Doppler
| pg. E 136
98
If a fetus is positioned face up, what could you do to optimize visualization of the spine?
Lower frequency to increase the penetration
| URR exam
99
At what age should a normal cranium be identified?
15 weeks
100
When is a head considered macrocephaly?
BPD and HC are 2+ SD above average
101
What might an asymmetric encephalocele raise suspicion for?
Limb-body wall complex
