Fetal Neural Tube Pathology Flashcards

1
Q

What does the ventricles contain?

A

4 connecting cavities within the cerebral hemispheres of the brain stem

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2
Q

The ventricles are continuous with what?

A

The spinal cord cavity

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3
Q

The Cavum septi pellucidi are located where in relation top the thalamus?

A

Anterior and slightly superior

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4
Q

What does the cavum septi pellucidi separate?

A

The anterior horns of the lateral ventricles

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5
Q

What is the CSF flow pattern?

A
  1. Lateral ventricles
  2. Interventricular foramen (Munro)
  3. 3rd ventricle
  4. Cerebral aqueduct
  5. 4th ventricle
  6. Two foramen, Magendie and Luschka
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6
Q

What does the cavum septi pellucidi visualization signify?

A

Normal development of the frontal midline

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7
Q

The cavum septi pellucidi is a important landmark for what measurements?

A

BPD where the cranium is measured

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8
Q

What is the criteria for ventricular measurement? 3

A
  1. Measure ventricle farthest from the transducer
  2. Measure at the level of the parietal occipital fissure
  3. Perpendicular to the cavity, inner to inner or “on to on”
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9
Q

Label the difference between the two

A

The left box is the CSP and the right box is the Fornix

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10
Q

What does the normal 3rd ventricle look like? And where is it located?

A
  1. Thin
  2. Located between the thalami and inferior to the corpus callosum
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11
Q

Where is the 4th ventricle located?

A

Anterior and inferior edge of the cerebellum

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12
Q

What is hydrocephalus?

A

Increase in CSF that results in enlargement of the ventricular system

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13
Q

Hydrocephalus is usually due to what? 2

A

Obstruction along the pathway of the CSF

  1. Intraventricular
  2. Extra ventricular
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14
Q

What is the most common cranial anomaly?

A

Hydrocephalus

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15
Q

What are causes of hydrocephalus? 2

A
  1. True hydrocephalus
  2. Ventricularmegaly
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16
Q

What is true hydrocephalus?

A

CSF obstruction

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17
Q

How would we get ventricularmegaly? 2

A
  1. Brain atrophy
  2. Small brain, ventricle have space to enlarge into
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18
Q

What are causes of true hydrocephalus? 3

A
  1. Neural tube defect
  2. Aqueduct stenosis
  3. Dandy walker malformation
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19
Q

What causes aqueduct stenosis? What does the lateral and 3rd ventricles look like? What about the 4th?

A
  1. CSF can not flow from 3rd ventricle to 4th
  2. Lateral and 3rd ventricle are enlarged
  3. 4th ventricle is normal
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20
Q

What causes intraventricular obstruction?

A

Aqueduct stenosis

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21
Q

What are some extra ventricular obstruction? 4

A
  1. Spina bifada
  2. Excess CSF
  3. Dandy walker malformation
  4. Sacral tumors
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22
Q

What is spinda bifida?

A

CSF can not flow normally through spinal canal and backs up in the ventricle of the brain

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23
Q

Which ventricles are affected by spina bifida?

A

All ventricles are affected

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24
Q

Excess secretion of CSF causing extraventricular obstruction comes from where?

A

Excessive section from a choroid plexus

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25
Q

How do we evaluate ventricular size?

A

Measure ventricular atrial diameter

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26
Q

Ventricular diameter does not change much from which dates?

A

15-35 weeks

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27
Q

What is the typical ventricle measurement ?

A

Around 7mm

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28
Q

What is the upper limit of normal for ventricular size?

A

10mm

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29
Q

What is the distance from medial ventricle wall to choroid?

A

<3mm

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30
Q

Additional anomalies occur in what percentage of cases of hydrocephalus?

A

70-80%

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31
Q

What are some things we see with posterior fossa views? 2

A
  1. Cisterna magna and cerebellum
  2. Skull deformities
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32
Q

What do we assess for in the cistern a magna and cerebellum? (What signs do we look for) 2

A
  1. Assess for obliterated cisterna magna, Cerebullum right up against the posterior skull
  2. Banana sign
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33
Q

What is dandy walker malformation? 2

A

A condition having

  1. Enlarged cisterna magna
  2. A defect in the cerebeller vermis
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34
Q

With DWM the cisterna magna communicates with the 4th ventricule how?

A

4th ventricle through the defect in the cerebellum

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35
Q

With DWM the ventricles may appear how?

A

Enlarge due to pressure in the posterior fossa

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36
Q

The DWM variant occurs when there is what?

A

Occurs when there is partial agenesis of the cerebella’s vermin’s, with smaller cisterna magna, and minimal dilation of the ventricles

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37
Q

Both DWM and DWM variant is associated with what?

A

Many syndromes

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38
Q

DWM is associated with what conditions? 6

A
  1. Agenesis of the corpus callosum
  2. Heart defects
  3. Genitourinary anomalies
  4. Polydactyly
  5. Intellectual impairment is common
  6. Fetal death is common
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39
Q

What risk factors increase the incidence of DWM? 3

A
  1. Maternal viral infection
  2. Alcohol consumption
  3. Diabetes
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40
Q

In terms of DWM, how big does the cisterna magna have to be to be abnormal?

A

> 1cm is abnormal

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41
Q

The cerebeller view of DWM must include what? 3

A
  1. Cavum septi pellucidi
  2. Peduncles
  3. Cerebellum
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42
Q

When assessing DWM what do we try to prove? 3

A
  1. Is the cisterna magna communicating with the 4th ventricle
  2. Is the cerebeller vermis absent or partially absent
  3. Are the ventricles enlarged?
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43
Q

What is the DDX for DWM? 2

A
  1. Arachnoid cyst in posterior fossa
    fluid collections in the layers of the arachnoid membrane
    These cysts can occur anywhere in the brain
  2. Mega cisterna magna
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44
Q

What are Choroid plexus cysts?

A

Cysts in the choroid plexus

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45
Q

When does CPCs disappear?

A

2nd trimester

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46
Q

What is CPC associated with?

A

Trisomy 18

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47
Q

What is the variation of incidence with T18 for CPC?

A

1 in 200 CPCs are associated with trisomy 18

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48
Q

One cause for Dolichocephaly is what?

A

Breech baby

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49
Q

What is the calculation for Cephalic index?

A

BPD / OFD and should be <75

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50
Q

What are craniosynotoses?

A

Bizarre fusion of the cranial sutures

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51
Q

What does craniosynostoses look like? Why?

A

Cloverleaf - all sutures fuse before the brain is finished growing

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52
Q

If the view of the brain is especially clear, you should consider what? 2

A
  1. Conditions which have poor mineralization
  2. Also, can the brain be compressed with slight pressure?
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53
Q

In osteogenesis imperfect and hypophosphatasia, the cranial bones are what?

A

Not ossified and the brain can easily be compressed

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54
Q

What is a acrania? How many children are affected?

A
  1. Absent cranium
  2. 1/1000 births
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55
Q

What is anencephaly?

A

No cerebral cortex - absent or destroyed

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56
Q

What is exencephaly? 3

A
  1. Some cerebral cortex, but is abnormal
  2. Brain tissue exposed to amniotic fluid damages the brain tissue
  3. May be early stage of anencephaly
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57
Q

On ultrasound, what does anencephaly look like? 3

A
  1. The facial structures and orbits are present
  2. No skull above the orbits
  3. Frog look
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58
Q

When can anencephaly be diagnosed? (weeks)

A

12-13 weeks

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59
Q

What is the prognosis of anencephaly?

A

Fatal

60
Q

What are some DDX for anencephaly? 2

A
  1. Amniotic band syndrome
  2. Large encephalocele
61
Q

What do we look for with amniotic band syndrome? 3

A
  1. Look for other amputations
  2. Waving membrane
  3. Watch to see if fetus seems stuck to side wall
62
Q

What would we look for with encephalocele?

A

Any sign of cranial bones

63
Q

What is an encephalocele?

A

Herniation of intracranial structures through a defect in the cranium

64
Q

What may encephaloceles contain? 2

A
  1. Only meninges
  2. Brain tissue also
65
Q

Most encephaloceles occurs where?

A

In the midline of the occiput, but can occur anywhere.

66
Q

If encephaloceles occur in the nasal area what might happen?

A

It might be difficult to see

67
Q

What lab value is affected by encephaloceles?

A

AFP is increased

68
Q

Can encephaloceles be isolated?

A

Yes

69
Q

What is Meckel- Gruber syndrome? (how lethal and if it a dominant or recessive condition)

A

An autosomal recessive lethal condition

70
Q

Encephalocele is often seen with what syndrome? What are signs? 3

A

Meckel- Bruner syndrome

Signs include
1. encephalocele
2. Cystic renal dysplasia
3. Polydactyly

71
Q

What does this image demonstrate?

A

Meckel-Gruber syndrome

72
Q

What is the sonographic appearance of encephalocele if only meninges protruding? 2

A
  1. Cystic structure with thin membrane
  2. Cranial defect present
73
Q

What does encephaloceles look like if the brain is protruding? 2

A
  1. Encapsulated echogenic mass, with cystic areas
  2. Cranial defect Present
74
Q

In terms of encephalocele, hydrocephalus occur due to what?

A

CSF blockage

75
Q

What does this image demonstrate?

A

Encephalocele

76
Q

What does this image demonstrate?

A

Encephalocele

77
Q

What does this image demonstrate?

A

Large encephalocele

78
Q

What is the DDX for a encephalocele? 2

A
  1. Cystic hygroma
  2. Teratoma
79
Q

In terms of a cystic hygroma, what should we see in a encephalocele?

A

Should see septations in cystic area with hygromas

80
Q

What does the prognosis for encephaloceles depend on? 3

A

Depends on
1. Size of the defect
2. Amount of the brain tissue involve d
3. Whether or not it is associated with Meckel-Bruner syndrome

81
Q

What are arachnoid cysts?

A

Are fluid filled collections in the layers of the arachnoid membrane

82
Q

Where can arachnoid cysts occur?

A

Anywhere in the cranium

83
Q

Arachnoid cysts are associated with what?

A

Nothing

84
Q

On u/s we see what in terms of arachnoid cysts? What might it demonstrate? 2

A
  1. Well defined cyst in brain
  2. May demonstrate mass affect
85
Q

What does this demonstrate?

A

Arachnoid cyst

86
Q

What is the DDX for arachnoid cysts? 2

A
  1. Dandy walker variant if in posterior fossa
  2. Porencephalic cysts
87
Q

What is the prognosis for arachnoid cysts?

A

Is good as long as the cyst does not destroy too much brain tissue or block ventricles

88
Q

When does porencephalic cysts occur?

A

When brain tissue is destroyed by hemorrhage or an infarct

89
Q

What are some things we see with porencephalic cysts look on U/S? 3

A
  1. Destroyed brain tissue becomes cystic
  2. Periventricular halo (close to lateral ventricles)
  3. May or May to communicate with ventricles
90
Q

What is the DDX for porencephalic cysts in a neonate? 3

A
  1. Dandywalker malformation
  2. Arachnoid cyst
  3. Hydrocephaly if it communicates
91
Q

What is the prognosis for porencephalic cysts in a neonate?

A

Depends on the degree of brain destruction

92
Q

What is hydranencephaly? What is still intact?

A
  1. Variable absence of cerebellum, or destruction of brain tissue
  2. Intact cranial vault and meninges
93
Q

What is the most severe form of porencephalic?

A

Hydranencephaly

94
Q

What causes hydranencephaly? 3

A
  1. Occlusion of ICA
  2. Infection or hemorrhage
  3. Destruction and resorption of brain matter
95
Q

How common is hydranencephaly?

A

Rare

96
Q

What does hydranencephaly look like sonographically? 3

A
  1. Intact thalami which are never fused and brain stem
  2. May or may not have intact Falx cerebri
  3. Irregular brain matter at periphery
97
Q

What is the DDX for Hydranencephaly? 2

A
  1. Severe hydrocephalus (smooth along periphery of cranium)
  2. Alobar holoprosecencephaly (would have fused thalami)
98
Q

Wha this the prognosis for Hydranencephaly?

A

Fatal

99
Q

What is schizencephaly? 2

A
  1. Symmetrical clefts in the parietal or temporal lobes that extend from the ventricles to the cortical surface
  2. Brain is split into anterior and posterior segments of the brain
100
Q

What is a lissencephaly? 2

A
  1. Smooth brain
  2. No sulcus or gyro due to abnormal migration of neurons from the germinal matrix
101
Q

When can we do a DX for lissencephaly?

A

Not possible until 3rd trimester

102
Q

What is Microcephaly?

A

Disproportionally small head compared to the gestation age and abdominal circumference

103
Q

What would classify the head as below 5th%

A

> 3 standard deviations below the mean head

104
Q

When would microscephaly be seen?

A

Late pregnancy

105
Q

What does Microcephaly implies?

A

Failure of brain development

106
Q

In terms of Microcephaly, ventriculomegaly occurs due to what?

A

Less brain tissue

107
Q

The profile of Microcephaly demonstrates what?

A

Sloping forehead

108
Q

What is Microcephaly associated with?

A

Many other developmental abnormalities

109
Q

Microcephaly results from what? 5

A
  1. Asphyxia - low oxygen
  2. Infections
  3. Drugs
  4. Alcohol
  5. Irradiation
110
Q

The corpus callosum starts to develop at how many weeks? And is not complete until when?

A
  1. 12 weeks
  2. 20 weeks
111
Q

What is the corpus callosum?

A

A bridge of white matter nerve fibres that connects the right and left cerebral hemispheres

112
Q

How does the corpus callosum develop?

A

From anterior to posterior

113
Q

Abscess of the corpus callosum may be complete or partial? Is it developmental or acquired?

A
  1. Complete or partial
  2. Developmental or acquired
114
Q

What would development mean in terms of corpus callosum?

A

Interruption of formation

115
Q

What does an acquired abscess mean in terms of corpus callosum?

A

Insults which cause secondary atrophy of previously devoted parts

116
Q

Can agenesis of the corpus callosum be isolated?

A

Yes

117
Q

What is agenesis of the corpus callosum often associated with? 2

A

Other CNS abnormalities such as

  1. Gerald dysplasia
  2. Dandy walker malformation

also associated with anomalies of the face limbs and genitourinary system

118
Q

What does agenesis of corpus callosum look like sonographically? 2

A
  1. Absence of CSP is your first clue
  2. Colpocephaly
119
Q

What is colpocephaly? 2

A

Lateral ventricles are teardrop shaped
1. Pointed anterior horns
2. Enlargement of the occipital horns only

120
Q

If ACC is suspected what do we do? 2

A
  1. Profile image, try to image from the top of the head in the midline sagittal plane
  2. Try EV if fetal head is low in pelvis
121
Q

Where does the Corpus callosum sit?

A

Superior to the cavum septi pellucidi

122
Q

If ACC is suspected, and if the CSP is absent the 3rd vent will be what?

A

Elevated or high riding in the head

123
Q

What is the prognosis of ACC? 2 (agenesis of the corpus callosum)

A
  1. If isolated and partial, it may not affect function at all
  2. Severity of decreased intellect depends on associated CNS abnormalities
124
Q

What does TORCH stand for?

A
  1. Toxoplasmosis
  2. Rubella
  3. Cytomegalovirus (CMV)
  4. Herpes simplex virus
125
Q

TORCH can cross the placenta and cause what? Followed by what? 3

A

Encephalitis followed by
1. Microcephaly
2. Ventriculomegaly
3. Calcifications

126
Q

What is toxoplasmosis due to? 2

A
  1. Contact with raw meat
  2. Cats, especially kitty litter
127
Q

CMV is common in what situations?

A

Large populations

128
Q

Herpes can be transplacentally acquired but more commonly due to what?

A

Vaginal delivery with herpes infection

129
Q

What is the sonographic appearance of TORCH? 6

A
  1. Look for signs of heart failure (enlarged heart)
  2. Pleural effusions
  3. Ascites
  4. Hepatosplenomegaly
  5. Hepatic calcifications
  6. Echogenic (calcified) Bowel
130
Q

What is the vein of Galen aneurysm?

A

A variety of Arteriovenous (AV) malformations drain into the vein of Galen and result in its distension as a single dilated midline fluid collection

131
Q

Vein of Galen aneurysm dilation does not occur until which trimester?

A

The 3rd trimester

132
Q

What does the vein of Galen look like sonographically? How does the neck vessels appear? What does the heart show?

A
  1. Dilated midline collection posterior to the thalamus and mid brain, between the posterior horns of the lateral ventricles
  2. Neck vessels may appear prominent
  3. Signs of heart failure (cardiomyopathy due to shifting)
133
Q

How can we easily DX Vein of Galen?

A

Colour doppler

134
Q

What is the DDX for vein of Galen? 2

A
  1. Arachnoid cysts
  2. Porencephalic cyst
135
Q

What is the prognosis of vein of Galen?

A

Poor unless all anastomoses can be cauterize

136
Q

Congenital brain tumors are how common?

A

Rare

137
Q

What is the most common lesion of the brain?

A

Teratoma

138
Q

What are Teratomas?

A

Large echogenic masses with cystic spaces and occasional calcifications

139
Q

What is the prognosis for tumours in the brain?

A

Dismal

140
Q

What is holoprosencephaly? 2

A
  1. Severe abnormality of the forebrain cleavage (cerebrum or prosencephalon)
  2. Fusion of the cerebral hemispheres and thalami
141
Q

What is holoprosencephaly associated with?

A

T13

142
Q

What are the three classifications of holoprosencephaly?

A
  1. Lobar - mild
  2. Semilobar
  3. Alobar - severe
143
Q

What is a lobar holoprosencepahly?

A
  1. Fused anterior horns that are squared off
  2. Incomplete Falx but 3rd ventricle may be seen
144
Q

What is the semilobar version of holoprosencephaly? 2

A
  1. Single horseshoe shaped ventricle with brain mantle
  2. No 3rd ventricle of Falx
145
Q

What is the Alobar version of Holoprosencephaly? 3

A
  1. Little or no corticosteroids mantle
  2. Single horseshoe shaped ventricle
  3. Fused thalami and no 3rd ventricle or Falx