Developmental Abnormalities

Question 1

Neural tube defecs are associated with low levels of ______ prior to conception

Answer 1

folate

Question 2

Neural tube defects are detected during prenatal care by elevated levels of ____________ in the amniotic fluid and maternal blood

Answer 2

alpha-fetoprotein (AFP)

Question 3

What is ancephaly?

Answer 3

Absence of the brain and skull

Question 4

What is the appearance of the fetus due to ancephaly?

Answer 4

“frog-like” appearance

Question 5

Why does maternal polyhydraminos occur in ancephaly?

Answer 5

The fetus doesnt swallow the amniotic fluid thus there is an increase in fluid volume

Question 6

What is spina bifida?

Answer 6

Failure of hte posterior vertebral arch to close, resulting in a vertebral defect (disruption of the caudal end of the neural tube)

Question 7

How does spina bifida present?

Answer 7

Presents as a dimple or patch of hair overlying the vertebral defect

Question 8

How does spina bifida clinically present?

Answer 8

Cystic protrusion of the underlying tissue through the vertebral defect

Meningocele - protrusion of meninges

Meningomyelocele - protrusion of meninges and spinal cord

Question 9

What is cerebral aqueduct stenosis?

Answer 9

Congenital stenosis of the channel that drains CSF from the 3rd ventricle into the 4th ventricle

Question 10

Describe the flow of CSF from site of production to the subarachnoid space

Answer 10

CSF is produced by the choroid plexus lining the ventricles

Flowes from the laterla ventricles –> 3rd ventricke via the interventricular foramen of Monro –> 4th ventricle via hte cerebral aqueduct –> subarachnoid space via the foramina of Magendie and Luschka

Question 11

What is the clinical presentation of cerebral aqueduct stenosis?

Answer 11

Enlarging head circumference due to dilation of the ventricles

Hydrocephalus

Question 12

What is the MCC of hydrocephalus in newborns?

Answer 12

Cerebral aqueduct stenosis

Question 13

What is Randy-Walker malformation?

Answer 13

Congenital failure of the cerebellar vermis to develop

Question 14

Clinical presentation of Randy-Walker malformation

Answer 14

Massively dilated 4th ventricle (posterior fossa) with an absent cerebellum; see image 17.2

Often accompanied by hydrocephalus

Question 15

What is Arnold-Chiari malformation (Type II)?

Answer 15

Congenital extension of cerebellar tonsils through the foramen magnum

Can cause obstruction of CSF leading to hydrocephalus

Question 16

What conditions may be associated with Arnold-Chiari malformation (Type II)?

Answer 16

Meningomyelocele

Syringomyelia