Fetal Abnormalities

Question 1

In what three stages can fetal abnormalities occur?

Answer 1

1. Dysraphism (Disorders of Primary Neuralation)
2. Disorders fo Prosencephalization
3. Cortical Development Disorder

Question 2

What two problems can arise from disorders of corticol development?

Answer 2

1. cellular proliferation
   - microencephaly
   - hemimegaencephaly
2. cellular migration

• gray matter heteropia
• lissencephaly
• schizencephaly

Question 3

what four syndromes can arise from disorders of primary neuralization (dysraphia)?

Answer 3

1. Ancephaly
2. Encephaly
3. Spina Bifida
4. Arnold Chiari Malformation Type II

Question 4

Meningoencephalocele aka an encephalocele is a cystic structure herniating through a __ defect.
This causes developmental delays.
Encephaloceles can be divided into:

1. __ __ - only involves skin, skull and meninges. Easy to fix and does not carry much morbidity. An example is a nasal meningocele (second most common)
2. ___ - Meninges, CSF, and brain herniate out through skull defect. A common one is the occipital encephalocele (Most common)
3. ___ - Meninges, CSF, brain, dura, and part of ventricles bulge out. Very difficult to fix

Why do these happen? What deficiency can cause this? What two drugs can cause these?

Answer 4

Meningoencephalocele aka an encephalocele is a cystic structure herniating through a skull defect.
This causes developmental delays.
Encephaloceles can be divided into:

1. encephalocele - only involves skin, skull and meninges. Easy to fix and does not carry much morbidity. An example is a nasal meningocele (second most common)
2. meningoencephalocele - Meninges, CSF, and brain herniate out through skull defect. A common one is the occipital encephalocele (Most common)
3. meningohydroencephalocele - Meninges, CSF, brain, dura, and part of ventricles bulge out. Very difficult to fix

It is from a primary neuralation disorder (dysraphia). It can happen from a folic acid deficiency, and from drugs like – Valproic acid, Carbamazepine

Question 5

___ ___ AKA Myeloschisis is a type of dysraphism.

These can be:

1. ___ (closed) - a defect in the vertebrae but the skin and meninges are intact. Not a big deal clinically

or they can be:

2. ___ (open). Under this category, pts can have a
3. ___ which is more mild. ___ bulges out, but nerves are still intact (pt presents with no neurological deficits)

or a 2. ____ which is more severe. Part of spinal cord and nerve roots bulge out (pt will have neurological deficits).

Clinical Presentation of these:

Below the level of meningocele/meningomyocele, pt will have: ___ness, ___ loss , loss of ___/___ control and loss of ____ function

Answer 5

Spina bifida AKA Myeloschisis is a type of dysraphism.

These can be:

1. oculta (closed) - a defect in the vertebrae but the skin and meninges are intact. Not a big deal clinically

or they can be:

2. aperta (open). Under this category, pts can have a
3. meningocele which is more mild. meninges bulges out, but nerves are still intact (pt presents with no neurological deficits)

or a 2. meningomylocele which is more severe. Part of spinal cord and nerve roots bulge out (pt will have neurological deficits).

Clinical Presentation of these:

Below the level of meningocele/meningomyocele, pt will have: weakness, sensory loss , loss of bowel/bladder control and loss of sexual function

Question 6

Arnold Chiari Malformation Type II Causes:

Herniation of ____ and cerebellar ___ below level of ___ ___. This is prone to cause ___, because it restricts outflow of ___ from the ventricles.

Types of hydrocephalus - build up of CSF in brain is called ____ hydrocephalus. There is still communication among ventricles, but there is no ___ of CSF.

__-___ ____ - Obstruction of outflow. This is what happens in CHIARI TYPE II.

Clinical presentation from hydrocephalus is:

Progressive enlargement of ___, __ing, death if not shunted.

Why does Arnold Chiari Type II happen?

Answer 6

Arnold Chiari Malformation Type II Causes:

Herniation of medulla and cerebellar tonsils below level of foramen magnum. This is prone to cause hydrocephalus, because it restricts outflow of CSF from the ventricles.

Types of hydrocephalus - build up of CSF in brain is called communicating hydrocephalus. There is still communication among ventricles, but there is no outflow of CSF.

Non-Communicating Hydrocephalus - Obstruction of outflow. This is what happens in CHIARI TYPE II.

Clinical presentation from hydrocephalus is:

Progressive enlargement of head, vomiting, death if not shunted.

Why does Arnold Chiari Type II happen?

- it occurs because of dysraphia, a disorder in primary neuralation. it is one of the four possible outcomes of this disorder.

Question 7

What are two possible sydromes from prosencephalization?

When does this happen and what causes this?

Answer 7

1. holoprosencephaly
2. septo-optic dysplasia

Disorders of prosencephalization occurs during the 4th and 5th week.

Causes: - Genetic (eg trisomy 13 and 18)

• Alcohol
• Maternal diabetes
• TORCHH infections (Toxoplasma, Rubella, CMV, Herpes, HIV)

Question 8

What are the syndromes associated with prosencephalization disroders?

_____

1. Lobar (most mild) 2. Semilobar 3. Alobar (most severe)
2. Lobar - the frontal lobes are distinct but not completely separated.
3. Semilobar HP - the frontal lobes are fused, but the occipital lobe isn’t;
4. Alobar HP - most severe, because there is no division into separate hemispheres at all.

__-__ ___

1. Absence of septum pellucidum
2. Absence or hypoplasia of __ __ - Blindness/visual impairment
3. ____ of pituitary - Pituitary insufficiency

Answer 8

What are the syndromes associated with prosencephalization disroders?

Holoprosencephaly

1. Lobar (most mild) 2. Semilobar 3. Alobar (most severe)
2. Lobar - the frontal lobes are distinct but not completely separated.
3. Semilobar HP - the frontal lobes are fused, but the occipital lobe isn’t;
4. Alobar HP - most severe, because there is no division into separate hemispheres at all.

Septo-optic Dysplasa

1. Absence of septum pellucidum
2. Absence or hypoplasia of optic nerve - Blindness/visual impairment
3. Hypoplasia of pituitary - Pituitary insufficiency

Question 9

__ __ disorder Occurs During Week __ to __.

Causes: Immature neurons are formed in germinal matrix (ventricular zone).

Waves of these neurons migrate along radial glia to surface of brain “__-__” pattern, with___ layers formed first, ___layers last.

These disorders cause 2 different syndromes. What are they?

• *1. __ __ disorders
  2. __ __disorders

what categories do these split up into?**

Answer 9

Cortical Development Disorder Occurs During Week 4-28

Causes: Immature neurons are formed in germinal matrix (ventricular zone).

Waves of these neurons migrate along radial glia to surface of brain “Inside-out” pattern, with inner layers formed first, outer layers last.

_Two disorders:
CELL PROLIFERATION DISORDERS_

1. Microencephaly:

- Primary - Genetic; structure of brain looks superficially normal

- Secondary - Due to injury, infection, drugs after initially normal cortical development

2. Hemi-megalencephaly

• A very rare condition - Cells go to the right place, but too many cells are formed.
• PTs are prone to UMN problems (spasticity), developmental problems and seizures

NEURONAL MIGRATION DISORDERS

1. Heterotopia
2. Lissencephaly
3. Schizencephaly
   - closed lip (does not cross to ventricles) or open lip