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OBGYN 2 > M5: Fetal Neuro Tube Pathology > Flashcards

M5: Fetal Neuro Tube Pathology Flashcards

(104 cards)

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1
Q

where is CSF produced

A

choroid

found on the floor of lat ventricles
roof of 3rd ventricle
post wall of 4th

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2
Q

landmarks for lat ventricles

A

CSP
antrum of ventricles
V of ambient cistern
Parietal-occipital fissure

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3
Q

How would you angle the probe from the posterior fossa view p the see the 4th ventricle

A

inferior

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4
Q

What is hydrocephalus

What commonly causes it?

A

An increase in CSF that results in enlargement of the ventricles

Usually due to obstruction long the path of the CSF

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5
Q

What is the most common cranial anomaly

A

Hydrocephalus

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6
Q

What is true hydrocephalus

A

CSF obstruction

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7
Q

What are the causes of true hydrocephalus

A

Neural tube defect
Aqueduct stenosis
Dandy walker malformations

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8
Q

What causes ventriculomegaly

A

Caused by brain atrophy which allows the ventricles more room to expand… NOT DUE TO OBSTRUCTION

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9
Q

What happens in aqueduct stenosis?

A
  • CSF can’t flow from the 3rd to the 4th ventricle
  • lateral and 3rd ventricles are enlarged
  • 4th ventricle is normal
  • larger ventricles lead to hardly any brain mantel developing
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10
Q

What is a cause of intraventricular obstruction that leads to hydrocephalus

A

Aqueduct stenosis

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11
Q

How will the choroid appear w/ aqueduct stenosis

A

Posterior choroid will be dangling

Anterior choroid will be resting on mid line

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12
Q

3 causes of extraventricular obstruction that lead to hydrocephalus

A

Spinal bifida
Excess CSF
Dandy walker malformation

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13
Q

How can spinal bifida cause extracellular obstruction hydrocephalus

Which ventricles does it effect

A

CSF can’t flow normally through the spinal canal and backs up into the ventricles

Effects all ventricles

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14
Q

Where do we measure the ventricles

What is the upper limit of normal

A

At the atria or parietal occipital fissure

Upper is 10mm

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15
Q

What should the measurement from the medial ventricle wall to the choriod be?

A

<3mm

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16
Q

If you see hydrocephalus, which view of the brain should you assess

A

The posterior fossa view

Look at cisterna magna and cerebellum to assess for:

  • obliterated cisterna magna
  • deformed cerebellum (banana)
  • lemon sign
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17
Q

When would the lemon sign be seen

A

2nd trimester

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18
Q

When does the lemon sign occur

A

Results when cranial contents are pulled towards the spine w/ Arnold chiari II malformations

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19
Q

How does the lemon sign appear of US

A

Frontal bones caved in

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20
Q

When does the lemon sign disappear

A

In 3rd trimester due to the resulting hydrocephalus from the enlarging ventricles of the blocked CSF

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21
Q

What type of Arnold chiari do we see on ultrasound

A

Type 2… other types are so lethal that fetus will die very early on

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22
Q

what is the banana sign

A

cerebellum in the shape of a banana and no cisterna magna

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23
Q

Describe dandy walker malformation. What characteristics should you look for

A
  • enlarged cisterna magna and absent cerebellar vermis
  • cisterna magna communicates w/ the 4th ventricle through the defect in the cerebellum (absent vermis)
  • ventricles can be enlarged due to pressure in the posterior fossa
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24
Q

What is a dandy walker variant

A

Partial agenesis of the vermis w/ smaller cisterna magna and minimal dilation of the ventricles

-associated w/ many syndromes

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25
What is DWM associated w/
-Intellectual impairment and fetal death - agenesis or corpus callosum - heart defects - genitourinary defects - polydactyly
26
The risk of DWM increases w/ what 3 things?
viral infection Alcohol Type 1 diabetes
27
What’s the differential diagnosis for DWM and how does it appear
Arachnoid cyst in posterior fossa -fluid collection in the layers of the arachnoid membrane
28
norm value for cisterna magna
<10mm
29
cerebellar view must include what
CSP peduncles cerebellum
30
what should you try to prove w/ DWM
cisterna magna communicating w/ 4th ventricle partial or full absence of vermis enlarged ventricles
31
when does the corpus callosum start to develop, when is development complete how does it develop/grow
12 wks, not complete until 20 wks anterior to posterior
32
can the absence of corpus callosum be partial or complete
yes
33
2 causes for an absent corpus callosum
developmental: interruption in formation acquired: damage that causes atropy of the CC
34
an absent corpus callosum is associated w/ what other abnormalities
- absent CSP (first clue) - other CNS abnormalities - DWM and gyral dysplasia (no folds/grooves on the brain due to lack of development) - `anomalies of the face. limbs and genitourinary sys
35
how will the anterior horns look w/ an absent corpus callosum occipital horns?
pointed enlarged (colpocephaly) all other ventricles are norm
36
when do CPCs usually disappear
2nd trimester
37
CPCs are associate w/ what chromosomal abnormality
T18 (must see open hands, if not, T18 suspected)
38
at what size are CPCs significant
>/= 3 mm
39
What is acrania
Absent skull
40
What is Anencephaly
No or destroyed cerebral cortex | this is the more commonly used term
41
What is exencephaly
Some cerebral cortex but it’s abnormal May be an early stage of anencephaly (brain exposure to amnitic fluid destroys brain tissue)
42
What does acranial lead to?
Leads to exencephaly and then anencephaly
43
What are the US features of anencephaly
``` Facial structures and orbits are present No skull above the orbits Polyhydramnios (baby can’t swallow) Active fetus Frog like face ```
44
Exencephaly can’t be diagnosed before how many wks prognosis?
12-13 wks fatal
45
DDX for anencephaly
anmiotic band syndrome - look for other amputations, waving memebrane or fetus stuck to the uterus large encephalocele - (herniation of brain and meningies outside of the skull)
46
What is hydraencephaly
Variable absence of the cerebrum and destruction of brain tissue Essentially a stroke in utereo
47
Which structures are intact w/ hydraencephaly
Cranial vault and meninges
48
Most severe form of porencephaly
hydraencephaly
49
What causes hydraencephaly
Occlusion of ICA Infection or hemorrhage Destruction and resorption of brain matter
50
Is hydraencephaly rare?
Yes
51
What causes the hemorrhage that leads to hydraencephaly
Lack of 02
52
How do you remember which artery is typically occluded and causes hydraencephaly
ICA has an A, and so does hydraencephaly
53
Us appearance of hydraencephaly
Intact thalami which are never fused May see brain stem Falx cerebri may or may not be present Irregular brain matter
54
Ddx for hydraencephaly
``` Severe hydro (smooth along the periphery of the cranium) Alobar holoprosencephaly (would have fused thalami) ```
55
Prognosis of hydraencephaly
Fatal
56
When do porencephalic cysts occur
When the brain tissue is destroyed by hemorrhage or infarct
57
Us appearance of porencephalic cysts
- Destroyed brain tissue that had become cystic - Usually seen close to the lateral ventricle - Cysts May or may not communicate with the ventricles
58
Ddx of porencephalic cysts
DWM Arachnoid cyst Hydrocephaly if cysts communicate w/ the ventricles
59
Prognosis of porencephalic cysts
Depends on degree of brain destruction
60
what are arachnoid cysts where do they occur
fluid filled collections in the layers of the arachnoid membrane can occur anywhere in the brain
61
are arachnoid cysts associated w/ any conditions
no
62
us appearance of arachnoid cysts
well defined cysts in the brain that may show the mass effect
63
DDX of arachnoid cysts
DWM variant in the posterior fossa | porencephalic cyst
64
prognosis for arachnoid cysts
good if the cysts dont destroy too much brain matter or block the ventricles
65
what is encephalocele what tissue can it contain
herniation of intracranial structures through a defect in the cranium only meninges or brain tissue also
66
where do most encephaloceles occur
midline of the occiput, but they can occur anywhere | if in the nasal area it can be hard to see
67
what lab value will be increased w/ encephalocele
AFP
68
encephalocele associations
isolated | Meckel Gruber syndrome
69
what is Meckel Gruber syndrome
an autosomal recessive lethal condition characterized by: encephalocele cystic renal dysplasia (lrg echogenid kidneys) polydactyly
70
Us appearance of encephalocele if only the meninges are protruding
cystic structure w/ thin membrane cranial defects hydrocephalus due to CSF blockage
71
Us appearance of encephalocele if brain matter is protruding
encapsulated echogenic mass w/ cystic areas cranial defects hydrocephalus due to CSF blockage
72
DDX for encephalocele
cystic hygroma - would see septations in the cystic area | teratoma
73
prognosis for encephalocele
depends on size, amount of brain tissue involved, and if there's an association w/ meckel gruber syndrome
74
what is schizencephaly
symmetrical clefts in the parietal or temporal lobes that extend from the ventricles to the cortical surface the brain is split into anterior and posterior segments of the brain
75
what is lissencephaly
smooth brain... no sluci or gyri develope due to abnorm migration of neurons from the germinal matrix
76
when is lissencephaly diagnosed
not until 3rd trimester
77
what is microcephaly when is it seen
disproportionately sm head compared to gestational age and AC... there is faliure of brain development late preg
78
US appearance of microcephaly
sloping forehead | ventriculomegaly due to less brain tissue being present
79
microcephaly is associated w/ which type of abnormalities
developmental
80
causes of microcephaly
``` asphyxia infection drugs alcohol irradiation ```
81
what is a vein of galen aneurysm
a variety of AV malformations that drain into the vein of galen which leads to its distention
82
when does a vein of galen aneurysm occur
3rd trimester
83
US appearance of vein of galen aneurysm
single dilated, midline fluid structure posterior to the thalamus (mid brain) found b/w the posterior horns of the lateral ventricles may have prominent neck vessels signs of heart faliure (CMO due to AV shunting)
84
can you diagnose vein of galen aneurysm w/ colour doppler
yes
85
DDx for vein of galen aneurysm
arachnoid cyst | porencephalic cyst
86
prognosis for vein of galen aneurysm
poor unless the anastomoses can be cauterized
87
are congenital brain tumors rare
yes
88
most common type of congenital brain tumor
teratomas - lrg echogenic masses w/ cystic spaces, sometimes calcifications
89
prognosis for congenital brain tumors
poor
90
what is craniosynostoses
bizarre fusion of the cranial sutures
91
what is cloverleaf
type of craniosynostoses where fusion of all the cranial sutures occur before the brain is finished growing
92
what is doligocephay
narrow head, baby's CI is < 75 percentile causes are breech or oligohydramnious
93
what is bradycephaly
wide head, baby's CI is > 85 percentile
94
what is poor cranial mineralization
skull bones arent ossified properly, brain structures will appear very easy to see
95
can the brain be compressed w/ slight pressure w/ poor cranial mineralization
yes
96
which 2 conditions have poor cranial mineralization and allow the brain to be compressed easily
osteogenesis imperfecta | hypophosphatasia
97
what are the 3 classifications of holoprosencephaly which type is the most common
1. Lobar - mild 2. Semilobar 3. Alobar - severe alobar
98
describe alobar holoprosencephaly
- little to no cortical mantle - single horseshoe ventricle - fused thalami and no 3rd ventricle or falx - no hemispheres
99
describe semilobar holoprosencephaly
- single horseshoe shaped ventricle w/ brain mantle | - no 3rd ventricle or falx
100
describe lobar holoprosencephaly
- fused anterior horns that appear square - incomplete falx - 3rd ventricle present, absent cavum septum pellucidi
101
describe the flow of CSF
- Lateral ventricles - foramen of monro/interventricular foramen - 3rd ventricle - aqueduct of Sylvius/cerebral aqueduct - 4th ventricle - foramen of magendie - (1, medial) - to spinal cord - foramen of luschka - (2, lateral) - to brain
102
what should you try to image if you suspect the corpus callosum is absent (ACC)
``` profile picture (hypo strucutre that sites superior to the CSP) 3rd ventricle evelated in the head ```
103
prognosis of ACC
-if isolated or partial, it may not effect function at all severity of decreased intellect depends on associated CNS abnormalities
104
Which ‘sign’ will you see in the fetal head if there’s agenesis of the corpus callosum
Equal sign and not the box

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