Pathoma: Developmental [Neural] Anomalies

Question 1

The walls of the neural tube go on to develop into the _____________.

Answer 1

CNS

Question 2

Neural-tube defects are correlated with _____________.

Answer 2

low folate levels prior to conception

Question 3

Neural-tube defects can be detected by ________ in maternal blood.

Answer 3

elevated alpha-feto protein

Question 4

A fetus with anencephaly will have prominent __________.

Answer 4

eyes (leading to an often-cited “frog-like appearance”)

Question 5

Anencephaly can result from ____________.

Answer 5

incomplete closure of the cranial side of the neural tube

Question 6

Why does anencephaly lead to polyhydramnios?

Answer 6

Because the fetus normally swallows and reabsorbs some of the amniotic fluid. Without the brain, however, the swallowing reflex does not occur and amniotic fluid builds up.

Question 7

What causes spina bifida?

Answer 7

Failure of the posterior vertebral arch to close

Question 8

Trace the path of CSF from its origin to the cerebral sinuses.

Answer 8

CSF is created by the choroid plexus in the lateral ventricles; passes through the foramen of Monro (aka interventricular foramen) into the third ventricle; passes through the cerebral aqueduct into the fourth ventricle; from the fourth ventricle it passes through three openings to the subarachnoid space; form the subarachnoid space it passes through the arachnoid granulations to the various cerebral sinuses.

Question 9

Describe the pathophysiology of Dandy-Walker malformations.

Answer 9

The cerebellar vermis – which divides the hemispheres of the cerebellum – fails to develop, leading to a failure of the cerebellum to develop and consequent hydrocephalus due to blocked cerebral aqueduct.

Question 10

What is Arnold-Chiari malformation?

Answer 10

When the cerebellar tonsils stick through the foramen magnum, leading to blockage of CSF flow.