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OBGYN 2 > M5: Fetal Neuro Tube Pathology > Flashcards

M5: Fetal Neuro Tube Pathology Flashcards

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
Q

What is DWM associated w/

A

-Intellectual impairment and fetal death

  • agenesis or corpus callosum
  • heart defects
  • genitourinary defects
  • polydactyly
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26
Q

The risk of DWM increases w/ what 3 things?

A

viral infection
Alcohol
Type 1 diabetes

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27
Q

What’s the differential diagnosis for DWM and how does it appear

A

Arachnoid cyst in posterior fossa

-fluid collection in the layers of the arachnoid membrane

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28
Q

norm value for cisterna magna

A

<10mm

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29
Q

cerebellar view must include what

A

CSP
peduncles
cerebellum

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30
Q

what should you try to prove w/ DWM

A

cisterna magna communicating w/ 4th ventricle
partial or full absence of vermis
enlarged ventricles

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31
Q

when does the corpus callosum start to develop, when is development complete

how does it develop/grow

A

12 wks, not complete until 20 wks

anterior to posterior

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32
Q

can the absence of corpus callosum be partial or complete

A

yes

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33
Q

2 causes for an absent corpus callosum

A

developmental: interruption in formation
acquired: damage that causes atropy of the CC

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34
Q

an absent corpus callosum is associated w/ what other abnormalities

A
  • 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
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35
Q

how will the anterior horns look w/ an absent corpus callosum

occipital horns?

A

pointed

enlarged (colpocephaly)

all other ventricles are norm

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36
Q

when do CPCs usually disappear

A

2nd trimester

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37
Q

CPCs are associate w/ what chromosomal abnormality

A

T18 (must see open hands, if not, T18 suspected)

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38
Q

at what size are CPCs significant

A

> /= 3 mm

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39
Q

What is acrania

A

Absent skull

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40
Q

What is Anencephaly

A

No or destroyed cerebral cortex

this is the more commonly used term

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41
Q

What is exencephaly

A

Some cerebral cortex but it’s abnormal
May be an early stage of anencephaly
(brain exposure to amnitic fluid destroys brain tissue)

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42
Q

What does acranial lead to?

A

Leads to exencephaly and then anencephaly

43
Q

What are the US features of anencephaly

A 
Facial structures and orbits are present
No skull above the orbits
Polyhydramnios  (baby can’t swallow)
Active fetus
Frog like face
44
Q

Exencephaly can’t be diagnosed before how many wks

prognosis?

A

12-13 wks

fatal

45
Q

DDX for anencephaly

A

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
Q

What is hydraencephaly

A

Variable absence of the cerebrum and destruction of brain tissue
Essentially a stroke in utereo

47
Q

Which structures are intact w/ hydraencephaly

A

Cranial vault and meninges

48
Q

Most severe form of porencephaly

A

hydraencephaly

49
Q

What causes hydraencephaly

A

Occlusion of ICA
Infection or hemorrhage
Destruction and resorption of brain matter

50
Q

Is hydraencephaly rare?

A

Yes

51
Q

What causes the hemorrhage that leads to hydraencephaly

A

Lack of 02

52
Q

How do you remember which artery is typically occluded and causes hydraencephaly

A

ICA has an A, and so does hydraencephaly

53
Q

Us appearance of hydraencephaly

A

Intact thalami which are never fused
May see brain stem
Falx cerebri may or may not be present
Irregular brain matter

54
Q

Ddx for hydraencephaly

A 
Severe hydro (smooth along the periphery of the cranium)
Alobar holoprosencephaly (would have fused thalami)
55
Q

Prognosis of hydraencephaly

A

Fatal

56
Q

When do porencephalic cysts occur

A

When the brain tissue is destroyed by hemorrhage or infarct

57
Q

Us appearance of porencephalic cysts

A
  • Destroyed brain tissue that had become cystic
  • Usually seen close to the lateral ventricle
  • Cysts May or may not communicate with the ventricles
58
Q

Ddx of porencephalic cysts

A

DWM
Arachnoid cyst
Hydrocephaly if cysts communicate w/ the ventricles

59
Q

Prognosis of porencephalic cysts

A

Depends on degree of brain destruction

60
Q

what are arachnoid cysts

where do they occur

A

fluid filled collections in the layers of the arachnoid membrane

can occur anywhere in the brain

61
Q

are arachnoid cysts associated w/ any conditions

A

no

62
Q

us appearance of arachnoid cysts

A

well defined cysts in the brain that may show the mass effect

63
Q

DDX of arachnoid cysts

A

DWM variant in the posterior fossa

porencephalic cyst

64
Q

prognosis for arachnoid cysts

A

good if the cysts dont destroy too much brain matter or block the ventricles

65
Q

what is encephalocele

what tissue can it contain

A

herniation of intracranial structures through a defect in the cranium

only meninges or brain tissue also

66
Q

where do most encephaloceles occur

A

midline of the occiput, but they can occur anywhere

if in the nasal area it can be hard to see

67
Q

what lab value will be increased w/ encephalocele

A

AFP

68
Q

encephalocele associations

A

isolated

Meckel Gruber syndrome

69
Q

what is Meckel Gruber syndrome

A

an autosomal recessive lethal condition characterized by:

encephalocele
cystic renal dysplasia (lrg echogenid kidneys)
polydactyly

70
Q

Us appearance of encephalocele if only the meninges are protruding

A

cystic structure w/ thin membrane
cranial defects
hydrocephalus due to CSF blockage

71
Q

Us appearance of encephalocele if brain matter is protruding

A

encapsulated echogenic mass w/ cystic areas
cranial defects
hydrocephalus due to CSF blockage

72
Q

DDX for encephalocele

A

cystic hygroma - would see septations in the cystic area

teratoma

73
Q

prognosis for encephalocele

A

depends on size, amount of brain tissue involved, and if there’s an association w/ meckel gruber syndrome

74
Q

what is schizencephaly

A

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
Q

what is lissencephaly

A

smooth brain… no sluci or gyri develope due to abnorm migration of neurons from the germinal matrix

76
Q

when is lissencephaly diagnosed

A

not until 3rd trimester

77
Q

what is microcephaly

when is it seen

A

disproportionately sm head compared to gestational age and AC… there is faliure of brain development

late preg

78
Q

US appearance of microcephaly

A

sloping forehead

ventriculomegaly due to less brain tissue being present

79
Q

microcephaly is associated w/ which type of abnormalities

A

developmental

80
Q

causes of microcephaly

A 
asphyxia
infection
drugs
alcohol
irradiation
81
Q

what is a vein of galen aneurysm

A

a variety of AV malformations that drain into the vein of galen which leads to its distention

82
Q

when does a vein of galen aneurysm occur

A

3rd trimester

83
Q

US appearance of vein of galen aneurysm

A

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
Q

can you diagnose vein of galen aneurysm w/ colour doppler

A

yes

85
Q

DDx for vein of galen aneurysm

A

arachnoid cyst

porencephalic cyst

86
Q

prognosis for vein of galen aneurysm

A

poor unless the anastomoses can be cauterized

87
Q

are congenital brain tumors rare

A

yes

88
Q

most common type of congenital brain tumor

A

teratomas - lrg echogenic masses w/ cystic spaces, sometimes calcifications

89
Q

prognosis for congenital brain tumors

A

poor

90
Q

what is craniosynostoses

A

bizarre fusion of the cranial sutures

91
Q

what is cloverleaf

A

type of craniosynostoses where fusion of all the cranial sutures occur before the brain is finished growing

92
Q

what is doligocephay

A

narrow head, baby’s CI is < 75 percentile

causes are breech or oligohydramnious

93
Q

what is bradycephaly

A

wide head, baby’s CI is > 85 percentile

94
Q

what is poor cranial mineralization

A

skull bones arent ossified properly, brain structures will appear very easy to see

95
Q

can the brain be compressed w/ slight pressure w/ poor cranial mineralization

A

yes

96
Q

which 2 conditions have poor cranial mineralization and allow the brain to be compressed easily

A

osteogenesis imperfecta

hypophosphatasia

97
Q

what are the 3 classifications of holoprosencephaly

which type is the most common

A
  1. Lobar - mild
  2. Semilobar
  3. Alobar - severe

alobar

98
Q

describe alobar holoprosencephaly

A
  • little to no cortical mantle
  • single horseshoe ventricle
  • fused thalami and no 3rd ventricle or falx
  • no hemispheres
99
Q

describe semilobar holoprosencephaly

A
  • single horseshoe shaped ventricle w/ brain mantle

- no 3rd ventricle or falx

100
Q

describe lobar holoprosencephaly

A
  • fused anterior horns that appear square
  • incomplete falx
  • 3rd ventricle present, absent cavum septum pellucidi
101
Q

describe the flow of CSF

A
  • 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
Q

what should you try to image if you suspect the corpus callosum is absent (ACC)

A 
profile picture (hypo strucutre that sites superior to the CSP)
3rd ventricle evelated in the head
103
Q

prognosis of ACC

A

-if isolated or partial, it may not effect function at all

severity of decreased intellect depends on associated CNS abnormalities

104
Q

Which ‘sign’ will you see in the fetal head if there’s agenesis of the corpus callosum

A

Equal sign and not the box

OBGYN 2 (15 decks)

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