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How much does the brain weigh?
@ 5 months
@ 9 months
@ 20 years
- 50 g
- 500 g
- 1500 g
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When does the cerebellum develop?
- in the first 2 years of life, very small for infants
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What are three primary neural tube closure defects?
- Anencephaly
- craniorachischisis
- Myelomeningocele
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What are 3 primary axialmesodermal defects?
- encephalocele (herniation of neural tissue)
- Meningocele (herniation of neural tissue)
- Split cord (closed defect)
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What are 3 tail bud defects?
- spina bifida occulta
- split cord (low)
- hydromyelia
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Anencephaly
definition/characteristics
time period
indicators
risk factors
- Definition/Characteristics: failure of closure of the anterior neural tube which causes area cerebrovasculosa which is frog-like facies, underdeveloped hypothalamus, and adrenal cortical hyperplasia
- Time period: 28 days of gestation
- Indicators: high alpha-fetoprotein in amniotic fluid and maternal blood
- Risk Factors: low folate in diet
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Occipital Encephalocele
Characteristics
- Characteristics: Malformed brain tissue extending through a defect in the cranium (occipital and/or posterior fossa)
- "Brain in a Bag"
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Spina Bifida
types
- Spina Bifida Occulta: missing part of vertebral arch and accompanied with a tuft of hair
- Meningocele: the leptomeniges extends out but not the spinal cord
- Myelomenigocele: spinal cord extends out, can be open (more common) or closed, and usually associated with Chiari malformation and hydrocephalus, lumbar level most common
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Chiari II Malformation
Characteristics
- Cerebellar tonsillar herniation
- small posterior fossa
- extension of medulla below foramen magnum
- kinking of medulla
- Hydrocephalus is associated with it due to stenosis/atresia of the cerebral aqueduct
- Myelomeningoceles are associated with it
- Beaked collicular plate
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Dandy-Walker Malformation
Characteristics
- Agenesis of cerebellar vermis causing cystic dilation of 4th ventricle and enlargement of posterior fossa
- Have arrestment of cerebellar development prior to 3rd month of gestation
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Holoprosencephaly
Characteristics
Causes
Classifications
- Characterized by failure of cerebral hemispheres to separate, cyclopia, proboscis, agnathia (jaw development problems), cleft lip/palate
- Caused by defects in SHG (Sonic Hedgehog Gene) syndromic or trisomsy 13 non-syndromic
- Classifications: Alobar, Semilobar, Lobar, Arrhinencephaly
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Agenesis of Corpus Callosum
Characteristics
Categories
- Characterized by:
- abnormal cingulate gyrus with radiating gyral pattern
- Bat wing shaped lateral ventricles
- Bundle of Probst
- Can be clinically silent
- Categories include:
- Sporadic or syndromic: Aicardi (infantile spasms, polymicrogyria) Andermann (sensorimotor neuropathy, dysmorphic features), Meckel-Gruber (occipital encephalocele, liver/kidney abnormalities)
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Cavum Septi Pellucidi
Characteristics
- Unfused leaflets of septum pellucidum
- recall septum pellucidum is first grey matter
- increased incidence in boxers (cause or effect though?)
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Cortical Dysplasia: Polymicrogyria
Characteristics
- Multiple small cerebral gyri
- fusion of molecular layer
- four or fewer cortical layers
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Cortical Dysplasia: Lissencephaly
Characteristics
Cause
- Smooth brain surface with fe cerebral gyri (Aguria or pachygyria)
- Miller-Dieker syndrome due to LIS1 gene deletion
- caused by contiguous gene deletion
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Hydranencephaly
Causes
- Intrauterine bilateral coratid artery region infarct after 20 weeks gestation
- Resorption of infarcted brain; replacement by fluid filled sac
- Head Transilluminates (remember North Dakota story)
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Kernicterus
Characteristics
Cause
Clinical Symptoms
- Characterized by deposition (gross yellow staining) in BG, thalamus, hippocampus, inferior olivary nuclei, subthalamic nuclei, dentate nuclei, and most cranial nerve nuclei producing neuronal death and reactive glial scarring
- Caused by bilirubin deposition due to passsage of unconjugated bilirubin through immature BBB compromised by hypoxia and acidosis
- Clinical Symptoms: if survived then deafness and choreoathetoid cerebral palsy
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