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Question 1

Lissencephaly

what is it

types

sx:

Answer 1

Smooth brain” due to incomplete neuronal migration.

This can have a few forms:

• Pachygyria: Broad, thick gyri
• Agyria: Lack of gyri
• Neuronal heterotopia: Cells in aberrant positions compared to a normal brain.

Symptoms:

Initially appears normal, but then develops seizures, mental deficiency, and spastic quadriplegia.

Question 2

Compare and contrast Arnold-Chiari Type I Malformation and Arnold-Chiari Type II Malformation.

Answer 2

Severity of Chiari Malformations has to do with how much of the cerebellum herniates, and what other brain tissues herniate with it / are effected.

• Type I: Inferior cerebellum herniates through the foramen magnum.
  
  • Usually asymptomatic.
• Type II: Cerebellar tissue and brainstem herniate through the foramen magnum, often accompanied by occipital encephalocele and/or lumbar myelomeningocele.

Question 3

Microcephaly

Answer 3

Calveria and brain are small, but the face is normally sized.

Significant mental deficiencies.

Inadequate pressure from the growing brain is what leads to the small neurocranium.

Question 4

Holoprosencephaly (HPE)

Answer 4

Telencephalic vesicles do not separate into right and left, but instead remain singular.

This is associated with facial anomalies, like cyclopia

Question 5

what is indicated in holocenphaly

Answer 5

Sonic Hedgehog (SHH) gene has been implicated.

Question 6

What are the four listed causes of microcephaly?

Answer 6

1. Infection
2. Maternal alcohol use
3. Ionizing radiation
4. Autosomal recessive primary microcephaly