CNS: Developmental Anomalies

Question 1

Neural plate forms what

Answer 1

neural tube

Question 2

Along what axis does the neural tube run

Answer 2

cranial-caudal axis of embryo

Question 3

what does the wall of the neural rube form

Answer 3

central nervous system tissue

Question 4

The hollow lumen of the neural tube forms what

Answer 4

ventricles and spinal cord canal

Question 5

What does the neural crest form

Answer 5

peripheral nervous system

Question 6

Neural tube defects arise from what

Answer 6

• incomplete closure of neural tube

- low folate levels prior to conception

Question 7

How are neural tube defects detected

Answer 7

• during prenatal care

- elevated alpha-fetoprotein (AFP) in amniotic fluid and maternal blood

Question 8

What is anencephaly

Answer 8

absence of skull and brain

-disruption of cranial end of neural tube

Question 9

What does an anencephaly child look like

Answer 9

‘frog-like’ appearance

Question 10

What gets disrupted during pregnancy in anencephaly

Answer 10

• maternal polyhydramnios

- fetal swallowing of amniotic fluid is impaired

Question 11

What is spina bifida

Answer 11

failure of the posterior vertebral arch to close

• vertebral defect
• disruption of caudal end of neural tube

Question 12

How does spina bifida occulta present clinically

Answer 12

dimple or patch of hair overlying the vertebral defect

Question 13

Meningocele

Answer 13

protrusion of meninges

Question 14

Meningomyelocele

Answer 14

protrusion of meninges and spinal cord

Question 15

What is the most common cause of hydrocephalus in newborns

Answer 15

cerebral aqueduct stenosis

Question 16

What is cerebral aqueduct stenosis

Answer 16

• congenital stenosis of channel that drains cerebrospinal fluid from 3rd ventricle into 4th ventricle
• accumulation of CSF in ventricular space

Question 17

Where is CSF produced

Answer 17

choroid plexus lining the ventricles

Question 18

what is the flow of CSF fluid

Answer 18

• lateral ventricles to 3rd ventricle via interventricular foramen of Monro
• 3rd ventricle into 4th ventricle via cerebral aqueduct
• 4th ventricle into subarachnoid space via foramina of Magendie and Luschka

Question 19

clinical presentation for cerebral aqueduct stenosis

Answer 19

enlarging head circumference due to dilation of ventricles

- cranial suture lines are not fused

Question 20

Dandy Walker Malformation

Answer 20

• congenital failure of cerebellar vermis to develop

- dilated 4th ventricle (posterior fossa) with an absent cerebellum

Question 21

What other abnormality does Dandy Walker Malformation usually accompany

Answer 21

hydrocephalus

Question 22

What is Arnold-Chiari Malformation (Type II)

Answer 22

Congenital downward displacement of cerebellar vermis and tonsil through the foramen magnum

Question 23

Obstruction of CSF flow commonly results in what for Arnold-Chiari malformation (Type II)

Answer 23

hydrocephalus

- occlusion of 4th ventricle

Question 24

Arnold-Chiari malformation (Type II) is associated with what

Answer 24

• Meningomyelocele

- Syringomyelia