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38 Cards in this Set

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**What is unique process post-injury happens in the brain?
Liquefactive necrosis; instead of a scar forming, the injured brain area disintegrates, leaving a cavity behind

(particular relavent re. ischemic injury)
The CNS is an ___________-derived structure.
Ectoderm
Ectoderm
Through a process of folding, the ectoderm gives rise to the _________.
neural tube
neural tube
After the neural tube is formed it elongates and differentiates anteriorly into the _______ [1]. In this ______ [2] region, the __________ [3] vesicles and _________ [4] form.
anterior, anterior, optic, diencephalon, telenencephalon mesencephalon, rhombencephalon
[1] brain
[2] anterior
[3] optic
[4] diencephalon, telenencephalon mesencephalon, rhombencephalon
During diverticulation, the ___________ are formed.
cerebral hemispheres
cerebral hemispheres
The _________ is the source of most of the neurons found in the CNS. At about 10 weeks, it gives rise to the __________, which remains until 34 weeks.
neural tube, germinal matrix
neural tube, germinal matrix
What does the germinal matrix lie adjacent to?
The caudate nucleus and other periventricular structures.
Why is the germinal matrix extremely vulnerable to hemmorhage?
1. Very metabolically active (mitotically active) and important in development so it is richly supplied with blood
2. It is a transient structure so its vascular does not have a lot of structural integrity
1. Very metabolically active (mitotically active) and important in development so it is richly supplied with blood
2. It is a transient structure so its vascular does not have a lot of structural integrity
What is the role of the germinal matrix?
It gives rise to neurons and glia that populate the cerebral cortex
The layers of the cerebral cortex are populated in _________ (descending or ascending) numerical order. Thus, the cortex develops in an inside out manner.
Descending. The primitive neurons/neuroblasts from the germinal matrix migrate out toward the pial border of the cortex then turn and travel inwards.
Descending.

The primitive neurons/neuroblasts from the germinal matrix migrate out toward the pial border of the cortex then turn and travel inwards.
As the cortex is populated with neurons and is contained within the calvaria but still needs room to expand, it undergoes ____________.
gyration
gyration
True or false: The brain is continuously building new synapses, and it continues to do so until death.
True
**True or False: Neuroprogenitor cells of the brain die shortly after birth.
False; neurons do have the capacity for renewal, but more so in certain regions than others
What are Cajal-Retzius cells (CR)?
Pioneer neurons formed at the beginning of cortical development that are restricted to the outermost layer of the cortex. During migration, the outward bound primitive neuron hit these cells before turning around and heading deeper into the cortex.
Pioneer neurons formed at the beginning of cortical development that are restricted to the outermost layer of the cortex. During migration, the outward bound primitive neuron hit these cells before turning around and heading deeper into the cortex.
How do neuroprogenitor cells play into the creation of new memories?
Continuous differentiation of neuroprogenitor cells in the hippocampus (dentate gyrus); these cells create new connections/synapses with neighboring cells--> creation of new memories
What are 3 examples of neural tube defects?
1. Anencephaly
2. Encephalocele
3. Spina Bifida
[1] When do neural tube defects generally occur in the course of pregnancy?
[2] What protein is elevated in such a defect?
[3] What nutrient supplement reduces the probability of defect?
[1] early in pregnancy
[2] alpha-fetoprotein
[3] folate/folic acid
What is anencephaly?
Neural tube defect; failure of development of brain due to lack of closure at the ANTERIOR neuropore-->complete absence of structures above the diencephalon; complete replacement of brain with fibrous tissue; 1:1000; likely environmental etiology

*note
Fatal neural tube defect
Failure of development of brain due to lack of closure at the ANTERIOR neuropore --> complete absence of structures above the diencephalon; complete replacement of brain with fibrous tissue (cerebrovasculosa)
1:1000
Likely environmental etiology

*note areas of cerebrovasculosa on following slide face
cerebrovasculosa: lots of blood vessels and fibrous tissues where brain tissue should be
What is encephalocele?
neural tube defect; Outpouching of epithelium-enclosed brain tissue through a cranial defect 

In the East, mostly anterior encephalocele, in the West, mostly occipital encephalocele

(think: ENcephalocele, ENclosure of brain tissue)
Neural tube defect
Outpouching of epithelium-enclosed brain tissue through a cranial defect

In the East, mostly anterior encephalocele
In the West, mostly occipital encephalocele (occipital also most common at 75%)

(think: ENcephalocele, ENclosure of brain tissue)
[1] What is spina bifida?
[2] What are the 4 subtypes?
neural tube defect; Failure of closure at the POSTERIOR neuropore
3 subtypes: spinal bifida occulta, meningocele, meningomyelocele, (rachischisis, craniorachisichisis totalis)
[1]
- Neural tube defect
- Failure of closure at the POSTERIOR neuropore
[2]
- 4 subtypes:
-- Spinal bifida occulta
--- Bony defect in vertebral column with no dura involvement, can be marked by tuft of hair
-- Meningocele
--- Herniation of dura (only) through bony defect
-- Meningomyelocele
--- Herniation of dura and tissue through bony defect
-- Rachischisis
--- Most severe, spinal cord completely open to air with no overlying meninges or connective tissue
--- Can extend further up the spine to the skull (craniorachisichisis totalis) and these cases are associated with anencephaly
What are two types of lesions of the posterior fossa?
1. Chiari malformations (Arnold-Chiari most common)
2. Dandy-Walker malformation
1. Chiari malformations (Arnold-Chiari [Type II Chiari] most common)
2. Dandy-Walker malformation
What is a Arnold-Chiari malformation? (e.g., How is it formed? What are the results?)
posterior fossa lesion; Arnold-Chiari malformation is formed by a herniation of the cerebellar tonsils into the foramen magnum. The results are: 1. pseudomicropolygyria, 2. noncommunicating hydrocephalus, 3. tonsillar gliosis, 4. flattening of the pons 5.
Posterior fossa lesion
Arnold-Chiari malformation is formed by a herniation of the cerebellar tonsils into the foramen magnum
The results are:
1. pseudomicropolygyria - cortex maintains organization but gyri and convolutions appear smaller
2. noncommunicating hydrocephalus
3. tonsillar gliosis
4. flattening of the pons
5. breaking of the tectum
6. abnormalities of the basicranial bones
7. lumbar meningomyelocele
8. c-spine takes an "S" appearance
What is a Dandy-Walker malformation?
What is the general treatment?
posterior fossa lesion; Vermal hypoplasia (ie, missing vermis in cerebellum)--> enlarged posterior cranial fossa and outpouching of the fourth ventricle (hydrocephalus)

treatment: shunt insertion
Posterior fossa lesion
Vermal hypoplasia (usually missing vermis in cerebellum) --> enlarged posterior cranial fossa and outpouching of the fourth ventricle (hydrocephalus)

Treatment: shunt insertion
What are two types of forebrain abnormalities?
1. Holoprosencephaly
2. Agenesis of the corpus callosum

failure of midline fusion
1. Holoprosencephaly
2. Agenesis of the corpus callosum

Failure of midline fusion
What is agenesis of the corpus callosum?
forebrain abnormality; No corpus callosum; can be the cause of mental retardation or personality problems but can also be asymptomatic
Forebrain abnormality
No corpus callosum
Can be the cause of mental retardation or personality problems but can also be asymptomatic
What is holoprosencephaly?
forebrain abnormality; midline structures of brain do not fuse; often correlates of failures of fusion of midline facial structures (cyclopia) (also associated with arrhinencephaly, kallman's syndrome, trisomy 13)
partial: lobar holoprosencephaly
Forebrain abnormality
Midline structures of brain do not fuse and can result in fused ventricles (giant midline cystic spaces); often correlates of failures of fusion of midline facial structures (cyclopia, single nostril)
Associated with:
- arrhinencephaly and anosmia
- Kallman Syndrome and hypogonadism
- Trisomy 13
Partial: lobar holoprosencephaly
[1] What causes migration disorders?
[2] What are 3 types (in the order of when they would occur during development)?
Neuronal migration disorders occur because of inappropriate or defective migration of neurons formed in the germinal matrix. Different disorders occur depending on when during development/migration they occur.

1. Lissencephaly
2. Pachygyria
3. Micropolygyria
What is lissencephaly? (when does it occur? what does it look like?)
A migration disorder; happens early in development; complete absence of gyri in the brain--> smooth contours
(associated with Miller-Dieker syndrome)
Migration disorder in early development
Complete absence of gyri in the brain--> smooth contours
(associated with Miller-Dieker syndrome [LIS1 mutation on Chr17])
What is pachygyria? (when does it occur? what does it look like?)
A migration disorders; occurs when migration is already underway; results in flattened and enlargened ("pachy") gyri; 4 cortical layers instead of 6
Migration disorders that occurs during migration
Results in flattened and enlargened ("pachy") gyri
4 cortical layers instead of 6 from migration impairment
What is micropolygyria? (when does it occur? what does it look like?)
A migration disorder; occurs late in migration (after when pachygyria would occur); four layer cerebral cortex with small gyri are seen
A migration disorder; occurs late in migration (after when pachygyria would occur);
Four layer cerebral cortex with small gyri are seen (instead of six)
What are 6 types of perinatal vascular injury?
What can result from these injuries?
1. Multicystic encephalopathy
2. Hydranencephaly
3. Ulegyria
4. Status Marmoratus
5. Periventricular Leukomalacia (PVL)
6. Syringomyelia

Cerebral palsy
What is multicystic encephalopathy?
perinatal vascular injury; Accumulation of small infarcts because of multiple ischemic insults in developing brain--> liquefactive necrosis-->cysts and holes throughout brain parenchyma
Perinatal vascular injury
Accumulation of small infarcts because of multiple ischemic insults in developing brain --> liquefactive necrosis --> cysts and holes throughout brain parenchyma
What is hydrancephaly? (What causes it? what does it look like?)
perinatal vascular injury; Caused by a complete occlusion of carotid arteries (usually internal). No brain tissue grows because there is no blood supply--> where the brain would be is a watery sac
Perinatal vascular injury
Caused by a complete occlusion of carotid arteries (usually internal). No brain tissue grows because there is no blood supply --> where the brain would be is a watery sac
What is ulegyria?
perinatal vascular injury; thinned out and gliotic gyria
Perinatal vascular injury
Thinned out and (often) gliotic gyria, from a variety of reasons, usually ischemia
What is status marmoratus?
perinatal vascular injury; excessive myelination of gray matter structures of basal ganglia (normally because of death in basal ganglia nuclei)
Perinatal vascular injury
Excessive myelination of gray matter structures of basal ganglia <-- normally because of ischemia with corresponding death in basal ganglia nuclei
What is periventricular leukomalacia (PVL)? What causes it?
perinatal vascular injury; atrophy and necrosis of white matter in and around ventricles; hypothesized to be caused by impaired perfusion at boundary zone between ventriculopetal and ventriculofugal arteries were metabolic requirements are high (cause of
Perinatal vascular injury
Atrophy and necrosis of white matter in and around ventricles, sometimes accompanied by hemorrhage
Hypothesized to be caused by impaired perfusion at boundary zone between ventriculopetal and ventriculofugal arteries where metabolic requirements are high
Cause of cerebral palsy in long-term survivors
What is syringomyelia?
perinatal vascular injury; liquefactive necrosis/hole in the spinal cord that can be either developmental (arnold chiari) or post-traumatic

can travel up and become syringobulbia
Perinatal vascular injury
Liquefactive necrosis/hole in the spinal cord that can be either developmental (Arnold Chiari) or post-traumatic

Can travel up and become syringobulbia (involving the brainstem)
What is syringobulbia? What is a particular concern in this defect?
perinatal vascular injury; liquefactive necrosis/hole within the brainstem; a particular concern is sudden death due to depression of the cardiorespiratory centers in the medulla
Perinatal vascular injury
Liquefactive necrosis/hole within the brainstem
A particular concern is sudden death due to depression of the cardiorespiratory centers in the medulla