CNS malformations

Question 1

What are Neural tube defects?

Answer 1

• congenital
• abnormal development of brain and/or spinal cord
• failure of embryonic neural tube to close
• mom folate deficiency
• supplement mom with folic acid to reduce NTD by 70%
• common, 1 in 1000 preg./year
• foetal death
• reduces prevalence of neural defects at birth

Question 2

What are the types of Neural tube defects?

Answer 2

• Anencephaly
• Encephalocele
• Spina bifida
  -occulta
  -meningocele
  -myelomeningocele

Question 3

List cranial deformities

Answer 3

• acrania
• craniosynostosis
• microcephaly
• congenital hydrocephalus

Question 4

What is acrania?

Answer 4

cranial vault nearly completely absent

Question 5

What is craniosynostosis?

Answer 5

premature closure of one or more of the cranial sutures

Question 6

What is microcephaly?

Answer 6

significant decrease in size of brain and skull

Question 7

What is congenital hydrocephalus?

Answer 7

increase in CSF volume (from many causes)

Question 8

What is hydrocephalus?

Answer 8

• excess fluid in cranial vault, or subarachnoid space
• caused by anything that: decreases reabsorption of CSF, increases CSF production, obstruction in ventricular system
• congenital (aqueduct stenosis, insults in utero) or acquired (infection, neoplasms, trauma)

Question 9

Compare non-communicating to communicating hydrocephalus ?

Answer 9

Non-communicating: obstruction in ventricular system

Communicating: impaired absorption of CSF

Question 10

What is Arnold-Chiari Type 1? *just know basics

Answer 10

• herniation of elongated segment of inferior cerebellar vermis and paranormal folia through foramen magnum
• asymptomatic or complication -> death
• hydrocephalus

Question 11

What is Arnold Chiari Type 11? *just know basics

Answer 11

• posterior cranial fossa abnormal shallow
• caudal herniation of medulla and part of cerebellar vermis through foramen magnum
• hydrocephalus if complication

Question 12

What is the pathophysiology of hydrocephalus (in an adult) ?

Answer 12

• obstruction to CSF flow (in ventricular system, or arachnoid vili)

• > increase volume CSF
• > dilation of ventricular system proximal to obstruction
• > increased pressure on brain
• > atrophy of cerebral cortex and degeneration of white matter
• > increase ICP
• > features of high ICP and

Question 13

What is the pathophysiology of hydrocephalus in a child?

Answer 13

• increases pressure on brain

• > enlargement of head
• > fontanelles enlarge, full, bulging (scalp skin thin and shiny, prominent surface veins, frontal bossing)
• > ICP increases
• > features of high ICP

Question 14

What is the flow of CSF?

Answer 14

Lat. ventricle choroid plexus

• > interventricular foramen
• > 3rd ventricle (+ CSF from plexus)
• > aqueduct -> 4th ventricle (+ CSF from plexus)
• > lateral median aperture
• > subarachnoid space
• > arachnoid vili of dural venous sinuses
• > venous blood