Congenital Malformations

Question 1

Describe Anencephaly

Answer 1

Failure of anterior neuropore to close
Brain does not develop
Incompatible with life
Increased AFP during pregnancy and AChE

Question 2

Describe Spina bifida occulta

Answer 2

Failure to induce bone growth around the spinal cord
Mildest form
Vertebrae fail to form around spinal cord
No increase in AFP
Asymptomatic; tuft of hair over defect.

Question 3

Describe Spina bifida with

meningocele

Answer 3

Meninges protrude through vertebral defect

Increase in AFP

Question 4

Describe Spina bifida with

meningomyelocele

Answer 4

Meninges and spinal cord protrude through vertebral defect; seen with
Arnold-Chiari Type II
Increase in AFP

Question 5

Describe Spina bifida with

myeloschisis

Answer 5

Most severe
Spinal cord can be seen externally
Increase in AFP and AChE

Question 6

Describe Type I Arnold-Chiari

malformation

Answer 6

Most common
Mostly asymptomatic in children
Downward displacement of cerebellar tonsils through foramen magnum
Frequent association with syringomyelia

Question 7

Describe Type II Arnold-Chiari

malformation

Answer 7

More often symptomatic
Downward displacement of cerebellar vermis
Compression of IV ventricle → obstructive hydrocephaly
Frequent lumbar meningomyelocele

Question 8

Describe Dandy-Walker

malformation

Answer 8

Failure of foramina of Luschka and Magendie to open → dilation of IV ventricle
Agenesis of cerebellar vermis and splenium of the corpus callosum

Question 9

Describe Hydrocephalus

Answer 9

Most often caused by stenosis of cerebral aqueduct
CSF accumulates in ventricles and subarachnoid space
Increased head circumference

Question 10

Describe Holoprosencephaly

Answer 10

Incomplete separation of cerebral hemispheres
One ventricle in telencephalon
Seen in trisomy 13 (Patau)