Neuro 17.1: Developmental Abnormalities Flashcards
Spina bifida leads to _______.
meningocele or meningomyelocele
What is anencephaly?
failure of closure of the neural tube at the cranial end
What is a herniation of the spinal cord + meninges called?
meningomyelocele
_______ leads to meningocele or meningomyelocele.
Spina bifida
What is a failure of closure of the neural tube at the cranial end called?
anencephaly
What does the wall of the neural tube go on to develop?
the CNS
What does the lumen of the neural tube go on to develop?
- the ventricles
- spinal cord canal
Dx?
- a congenital extension of the cerebellar tonsils thru the foramen magnum hydrocephalus
Arnold-Chiari malformation
Dx?
- a congenital stenosis of the channel that drains the CSF from the 3rd and 4th ventricles enlarging head circumference
cerebral aqueduct stenosis
What is a herniation of only the meninges called?
meningocele
What is spina bifida?
failure of closure of the posterior vertebral arch at the caudal end
Why does hydrocephalus occur in Arnold-Chiari malformation?
CSF flow is obstructed
What causes a neural tube defect? When?
- incomplete closure of the neural tube
- due to low folate levels prior to conception
How does a Dandy-Walker malformation present?
- massively dilated 4th ventricle
- absent cerebellum
- hydrocephalus
What are the s/s of a Type 2 Arnold-Chiari malformation?
CSF flow obstruction –> hydrocephalus
The neural plate invaginates to create a ______.
neural tube
How are folate levels detected in prenatal screenings?
low = elevated AFP in amniotic fluid and maternal blood
Describe the flow of CSF, starting with the lateral ventricles.
lateral ventricles –> foramen of Monroe –> 3rd ventricle –> cerebral aqueduct –> 4th ventricle
_____ leads to a dimple or patch of hair overlying the vertebral defect.
Spina bifida occulta
Dx?
- a congenital failure of the cerebellar vermis to develop
Dandy-Walker malformation
How does cerebral aqueduct stenosis present?
an enlarging head circumference
What does cerebral aqueduct stenosis cause?
accumulation of CSF in the ventricles
An Arnold-Chiari malformation may occur in association with _______ and _______.
- meningomyelocele
- syringomyelia
Why is polyhydramnios seen in anencephaly?
- no brain = baby can’t swallow
- no swallow = increased amniotic fluid = polyhydramnios
What does anencephaly look like clinically in the baby and the mother?
- absence of the skull and brain
- frog-like appearance of the fetus (prominent eyes)
- maternal polyhydramnios
What is cerebral aqueduct stenosis?
a congenital stenosis of the channel that drains the CSF from the 3rd and 4th ventricles
What is a meningocele?
a herniation of only the meninges
What is a Dandy-Walker malformation?
a congenital failure of the cerebellar vermis to develop
Dx?
- absence of the skull and brain
- frog-like appearance of the fetus
anencephaly
What do the neural crests go on to develop?
the PNS
What is a failure of closure of the neural tube at the caudal end called?
spina bifida (failure of posterior vertebral arch closure)
Dx?
- massively dilated 4th ventricle
- absent cerebellum
- hydrocephalus
Dandy-Walker malformation
What makes CSF?
the choroid plexus
What is the cerebellar vermis?
a separation of the 2 sides of the cerebelllum
What is a meningomyelocele?
spinal cord + meninges
Spina bifida occulta leads to _______.
a dimple or patch of hair overlying the vertebral defect
lateral ventricles –> ______ –> 3rd ventricle –> cerebral aqueduct –> 4th ventricle
foramen of Monroe
Where can a neural tube defect occur?
at the head or the tail of the spinal cord
What is an Arnold-Chiari malformation?
a congenital extension of the cerebellar tonsils thru the foramen magnum
What are the s/s of a Type I Arnold-Chiari malformation?
none
What is the medical term for enlargement of the brain ventricles?
hydrocephalus
