Chapter 24 - Neurodevelopmental disorders Flashcards
What’s the broad definition of neurodevelopmental disorders?
- Multifaceted conditions generally defined by significantly lower-than-average performance in a school subject
- Origin in abnormal brain development
- Encompasses disorders of attention, social behaviour, general cognition, learning, communication, motor skills
What are the general stages of brain development?
1) Cell birth (neurogenesis; gliogenesis)
2) Neural migration
3) Cell differentiation
4) Neural maturation (dendrite and axon growth)
5) Synaptogenesis
6) Cell death and synaptic pruning
7) Myelogenesis
Which brain development stages occur prenatally and which continue well into adulthood?
- Cell birth - cell differentiation: Prenatally
- Neural maturation - Myelogenesis: Continues well into adulthood
What important development occurs during weeks 4-6?
- The neural tube is forming, very sensitive to insults (ex. drinking)
Why are gestational weeks 6-8 weeks so important for neural development?
- Neurogenesis is in full force and new neurons are developing, and neural migration is about begin
How does dendritic growth differ from axonal extension?
- Dendritic growth - helps provide surface area for synapses with other cells; occurs very slowly (arborization)
- Axonal extension - to appropriate targets to initiate synapse formation; occurs very quickly (1000X faster)
T/F: Most intellectual disability cases are mild.
- TRUE
Which sex is more diagnosed with intellectual disabilities? What’s a major risk factor?
- Males are more commonly diagnosed
- Poverty is a risk factor
What’s Cerebral Palsy (CP)?
- Group of motor function disorders caused by brain damage or abnormalities either before, during, or after birth
- Diverse causes can include blood clots, infections, and a wide range of traumatic brain injuries
- Considered an intellectual disability
What are some of the major symptoms of CP?
- Can be mild impairments in a single limb to severe impairments which can affect the entire body
- May be accompanied by other impairments (cognitive, emotional, epilepsy etc.)
- 35-60% of cases are associated with moderate to profound intellectual impairment
Is there a difference between incidence of CP in male and females?
- No
What’s considered a risk factor for CP?
- Premature births can increase incidence by 100-fold
What’s spastic CP?
- Makes up around 50% of cases
- Characterized by hypertonia (excessive muscle tone), worse when limbs are moved quickly
What’s athetoid CP?
- Makes up around 25% of cases
- Characterized by continuous ongoing movement (uncontrolled)
- Often caused by severe oxygen deprivation at birth, basal ganglia and thalamus are affected
What’s rigid CP?
- Makes up around 10% of cases
- More continuous, uniform hypertonia, affects whole body
- More severe than spastic
- Brain regions affected: basal ganglia, brain stem, and spinal cord
What’s ataxic CP?
- Affects around 10% of cases
- Caused by cerebellum damage, may need an aid to walk on their own
- Balance and coordination and voluntary movement most affected
- The least severe form of CP
What’s hypoxia?
- Diminished oxygen flow during
- May lead to an intellectual disability
What’s hydrocephalus?
- Abnormal buildup of CSF in the ventricles
- CSF bathes entire brain (cushions, adds buoyancy, provides ions etc.)
- CSF flow is blocked
- Atrophy of surrounding brain tissue leads to ventricle enlargement
When does infant hydrocephalus develop?
- Usually develops during first 3 months
- Affects around 2/1000 babies
Where is CSF produced and where does it move to?
- Produced in the choroid plexus
- Moves downward to the fourth ventricle
Where may CSF get blocked in hydrocephalus?
- The cerebral aqueduct
- The fourth ventricle
- The foramen of Magendie
- Foramen of Luschka
- Foramen of Monro
How does CSF circulate throughout the brain?
- The subarachnoid space (found between the arachnoid membrane and the pia mater)
What’s the most common cause of hydrocephalus?
- Most are the result of inflammation of trauma
What are the treatments for hydrocephalus?
1) Endoscopic third ventriculostomy (drilling a hole in the third ventricle, allows for fluid to leak out)
2) Shunt (permanent, inserted into lateral ventricle, most common solution)
What’s Fragile-X Syndrome?
- The most common inherited cause of an intellectual disability and autism spectrum disorder
Which sex has more learning disabilities with Fragile-X syndrome?
- Most boys have learning disabilities, compared to only 1/3 of affected girls