Lecture Week Three: Neurodevelopment & degeneration Flashcards
What are the 3 key steps in Primary Neurulation?
- Neural Plate forms (approx 18 days of development)
- Subsequent formation of the neural groove and neural fold
- Connection of the neural folds forms the neural tube
In what week does the neural tube close?
4th week of development
What does the Neural Tube develop into?
The Central Nervous System
What happens during the 3rd week of development? (1)
Folding of the neural tube
What happens during the 4th week of development? (1)
Neural tube closes
What happens during the 5th week of development? (2)
- Neural tube folds
- Separate CNS areas are emerging
What happens during the 6-7th week of development? (2)
- Telencephalon (lobes of the brain) start to enlarge
- CNS structures continue to develop
What happens during the 8-12th week of development? (3)
- Neurons proliferate and migrate
- Cerebral cortex begins to form
- Cerebellar cortex begins to form
What happens during the 12-16th week of development? (2)
- Neurons proliferate and migrate
- Areas of the CNS develop more intricately
What happens during the 16-40th week of development? (3)
- Neuronal migration
- Myelination Begins
- Synapse formation
What malformations can occur in the 3rd week of development? (1)
Neural tube defects
What malformations can occur in the 4th week of development? (2)
- Neural tube defects
- Holoprosencephaly ( L/R hemispheres don’t divide)
What malformations can occur in the 5th week of development? (2)
- Holoprosencephaly ( L/R hemispheres don’t divide)
- Sacral cord abnormalities
What malformations can occur in the 6-7th week of development?
No major malformations should occur during this period
What malformations can occur in the 8-12th week of development? (1)
- Migration/proliferation abnormalities (e.g. abnormal gyri)
What malformations can occur in the 12-16th week of development? (1)
- Migration/proliferation abnormalities (e.g. abnormal gyri)
What malformations can occur in the 16-40th week of development? (1)
Haemorrhage (ruptured blood vessel) or other destructive events
What does congenital mean?
Congenital means an illness or abnormality that is present before and/or at birth
What is one of the most common congenital CNS malformations?
Spina Bifida (Meningomyelocele)
- occurs from incomplete folding of the neural tube, leaving the spinal cord exposed
- Symptoms vary depending on extent and location of opening
- effects 5000 people in Australia
- 85-90% also have hydrocephalus (accumulation of cerebrospinal fluid in the brain)
What is a Chiari Malformation and how does it link to Spina Bifida (Myelomeningocele)?
Chiari Malformation is when the base/back of the brain is forced down through the skull into the top of the spinal canal. Occurs because Spina Bifida can cause Hydrocephalus (Accumulation of CSF) which presses on the brain pushing it down and out through the base of the skull.
What are some symptoms of Spina Bifida Meningomyelocele?
- Incontinence (involuntary evacuation of bowel and bladder)
- Motor impairments including paraplegia
- Cognitive impairments (difficulties with language, memory, attention, executive function)
In terms of Spina Bifida, the outcomes and symptoms experienced depend on 3 things. What are they?
- Extent of CNS malformation
- Complications such as shunt revisions (needing to re-do a surgery to fix a non-functional shunt [tube placed in brain to drain excess CSF]) or infection
- Environmental enrichments and SES
What is considered low birth weight?
Less than <2,500 g
What is considered very low birth weight?>
Less than <1,500g
What is considered extremely low birth weight?
Less than <750 g
How many weeks is considered Preterm birth
Less than <37 weeks gestational age
How many weeks is considered Very Preterm birth?
Less than <32 weeks gestational age
How many weeks is considered Extremely Preterm birth?
Less than <29 weeks gestational age
What is normal weight and term for birth?
Normal weight = over > 2,500 g
Normal Term = around 40 weeks (no less than 37)
Babies with congenital neurological conditions (e.g. cerebral palsy) are often born ____term and/or have ____ birth weight
Preterm and low birth weight
What are the survival rates (%) for babies born in the following weight ranges?
- 501-750g
- 751-1,000g
- 1,001 -1,250g
- 1,251-1,500g
- 501-750g = 55%
- 751-1,000g = 88%
- 1,001 -1,250g = 94%
- 1,251-1,500g = 96%
Between 1960 and 1983, how many times greater (x) were the survival rates of infants born with low birth weight?
x70 times greater
What are the 3 causes of CNS damage in infants with very low birth weight and very preterm births?
- Infection
- Insult (sudden disturbance in cerebral blood flow)
- Disruption to normal neurodevelopmental processes
What are the three main neuropathological changes that occur in VLBW VPTB babies with CNS damage?
- Enlarged ventricles
- Reduced white and gray matter
- Cortical malformations
What are the 4 factors that effect the LONG TERM outcomes of people born VLBW/VPTB?
- Birth weight and gestational age
- Medical complications
- Family environment
- Sex
Cognitive outcomes for Children with VLBW/VPTB are evident from early/middle/late life?
Early life
VLBW/VPTB effects the development of which three categories?
- Motor development
- Language
- Attention
Cognitive outcomes for children with VLBW/VPTB are most severe in those who also have _____ complications
Neonatal complications: complications that develop after or during the birthing process
Do children with VLBW/VPTB have difficulties that persist throughout adulthood, or just childhood?
Through adulthood as well.
What were IQ ranges like for children born in these 3 weight categories?
- <750g
- 750-1,499 g
- Full-term (1,500 +)
- <750g had the highest rate of IQ scores for both the 70-84 range and <70 range (compared to other weight classes)
- Full Term babies had the highest % in the 100-114 IQ range
- 750-1,499g group peaked at IQ range of 85-99, but were also the only group to have children in the >130 IQ range as well
What two neuropsychological factors are most impacted on by VLBW of <750g?
- Executive functioning (significantly impacted)
2. Visual-motor (majorly impacted, but less so than EF)