Module 11 : Fetal Neural Tube Pathology Flashcards Preview

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Flashcards in Module 11 : Fetal Neural Tube Pathology Deck (31)
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1

What produces CSF

Choroid plexus

2

Where are the choroid plexus located

- body of lat ventricle
- roof of third vent
- superior lateral walls of fourth vent

3

Flow of CSF through the brain

Choroid plexus >> lat vents >> interventricular foramen >> 3rd vent >> cerebral aqueduct >> fourth vent >> megendie ( spinal cord) and Lushka ( brain)

4

Normal fourth vent location

- anterior and inferior edge of cerebellum

5

Hydrocephalus

- increase in CSF that results in enlargement of ventricular system
- usually due to obstruction along the pathway to CSF
* MOST COMMON CRANIAL ANOMALY
- dangling choroid

6

Intraventricular obstruction hydrocephalus - aqueduct stenosis

- csf can’t flow from 3rd vent to 4th vent
- lat and 3rd bent enlarged but 4th vent normal

7

Extraventricular obstruction hydrocephalus - spine bifida

- CSF can’t flow normally through the spinal canal and back up in ventricle of brain
- ALL ventricles effects s

8

Extraventricukar obstruction hydrocephalus - excess CSF

- less common
- excess secretion from a choroid plexus papilloma (tumor)

9

Types of extraventricular obstruction hydrocephalus

- spina bifida
- excess CSF
- dandy walker malformation

10

Evaluating ventricular size

- measure ATRIAL diameter
+ size doesn’t change much 15 - 35
+ normal size 7mm
+ 10 mm upper limit of normal
- < 3mm from medial vent wall to choroid

11

Dangling choroid

- always rests in a gravitationally dependent position
- sign of hydrocephalus

12

True hydrocephalus

- either from CSF obstruction OR ventriculomegaly resulting from brain atrophy

13

Causes of true hydrocephalus

- neural tube defect NTD
- aqueductal stenosis
- dandy walker malformation

14

Ventriculomegalyt

- brain atrophy result in a smaller brain allowing ventricles more room to expand

15

Where to look when hydrocephalus is suspected

- additional anomalies tend to occur with hydrocephalus
- posterior fossa views
+ cisterna magna and cerebellum
= obliterated cisterna magna
= deformed cerebellum (banana)
= lemon sign

16

Banana sign

- indicates obliterated cisterna magna
- often ARNOLD CHIARI
-

17

Lemon sign

- resulting when cranial contents are pulled toward spine with Arnold Chiari II malformation
+ associated with spina bifida
- frontal bones caved in
- seen in second trimester
- lemon sign disappears in 3rd trimester due to resulting in hydrocephalus from enlarging ventricles of blocked CSF

18

Dandy walker malformation DWM

- enlarged cisterna magna and defect in the cerebellar VERMIS
- the cisterna magna communicates with the 4th vent through a defect in cerebellum
- ventricles can be enlarged due to pressure in the post fossa

19

Dandy walker variant

- partial agenisis of the vermis with a smaller cisterna magna and minimal dilation of the ventricles
- associated with many syndromes

20

DWM associated with

- intellectual impairment and fetal steam
- AGENISIS OF CORPUS CALLOSUM
- heart defects
- genitourinary
- polydactyly
- increase risk
+ maternal viral infection
+ alcohol consumption
+ maternal diabetes

21

Assessing DWM

- cisterna magna > 1cm abnormal
- cerebellar view must include
+ caveman septi pellucidi
+ peduncles
+ cerebellum
- measure

22

What to prove for DWM

- cisterna magna communicates with 4th vent
- cerebbellaR VERMIS absent or partially absent
- enlarged ventricles
- DDx = arachnoid cyst in posterior fossa

23

Arachnoid cysts in post fossa

- fluid collections in the layers of teh arachnoid membrane
- cysts can occur anywhere in the brain

24

Choroid plexus cysts CPC

- cysts in choroid plexus
- usually disappear in 2nd trimester
- associated with trisomy 18
+ 1 / 200 are associate with T18
- HAVE TO BE > 3MM

25

Nuchal fold

- 80% of infants with T21 have redundant skin in the posterior part of the neck
- can only be assessed between 16 and 20 weeks because of gestational diabetes

26

Gestational diabetes mellitus

- mothers with GDM the fetus can be LGA
- baby will have more fat in general making nuchal fold thick
- occurs after 20 weeks
- continuing to measure nuchal fold with make lots of false positives

27

Assessing nuchal fold

- greater than or equal to 6 mm abnormal
- measure from outer skull to outer skin surface

28

Acrania

- absent skull / cal aria

29

Anencephaly

- no or distorted cerebral cortex

30

Exenceohaly

- some cerebral cortex but abnormal
- early stage of anencephaly
- brain tissue exposed to amniotic fluid gets damages
- brain tissue in beginning (excencephaly) then by time fetus is imaged there is minimal tissue left so diagnosed anencephaly