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Block 4 PATH Exam -- Intro to Neuropathology

Terms

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What is neuropil?
Brain tissue that lies between cell bodies
Network of UNmyelinated neuronal processes
What are ependymal cells?
Cells where CSF is made and stored
Which cells are the macrophages of the CNS?
Microglia
What are the 3 layers of the cerebellum?
Molecular
Purkinje
Granular
Cell bodies in this region have melanin within them
Substantia nigra

(melanin is a byproduct of DA metabolism)
LFB is used to stain what?
Myelin
(LFB = Luxol Fast Blue)
What do silver stains highlight?
Axons, neurites
What is synaptophysin?
Pre-synaptic protein in neurosecretory vesicles

Staining for this produces a brown stain
Microvacuolation happens in response to hypoxic/ischemic damage

What is actually taking place, presenting as microvacuolation?
Swelling of mitochondria and SER/RER
Sequence of microscopic changes in hypoxic/ischemic lesions
1 hour -- Microvacuolation
4-12 hours -- RED NEURON (eosinophilia, pyknosis)
15-24 hours -- PMN infiltration begins
2 days -- Macrophage infiltration begins
5 days -- PMN infiltration ceases

~ 1 week -- Proliferation of astrocytes
What are nissl bodies?
Granular ER & ribosomes in nerves
What 2 brain regions are particularly susceptible to hypoxic injury?
Sommer's sector (CA1) of hippocampus
Purkinje cells of the cerebellum
What is a watershed area?
Where vascular beds from 2 arteries meet & form anastamoses
(essentially, "border zones" between regions supplied by diff. arteries)
What are watershed areas particularly susceptible to?

In what circumstances in particular?
Susceptible to infarcts

Particularly susceptible during systemic HYPOtension
What brain regions are INFANTS more prone to hypoxic injury in?
Hippocampus
Colliculi
What brain regions are ADULTS more prone to hypoxic injury in?
Outlying cortical regions
Hippocampus
Purkinje cell layer of cerebellum
What part of cells are Marinesco bodies found in?
Nucleus
What part of cells are Lewy bodies and Pick's bodies found in?
Cytoplasm
These structures are characteristic of Alzheimer's (2)
Neurofibrillay tangles
Neuritic plaques
Where are axonal balls found (in contrast to Lewy bodies, etc.)?

What are they a hallmark of?
Found in AXONS
(as opposed to cell bodies)

Hallmark of shearing injury
What are neuritic plaques composed of?
APP or Beta 4-amyloid
These are the myelinating cells of the CNS?

Of the PNS?
Oligodendrocytes

Schwann cells
What is gliosis?
Astrocyte production of glial scars after injury
What is GFAP?

What is it used as a marker for?
Acid Glial Filament Protein

Used as a marker for astrocytes
This type of astrocyte is responsible for acute response
Gemistocytic

(Remember, "fried eggs in chicken wire")
This type of astrocyte is responsible for chronic response
Fibrillary
Leukodystrophy
Leukoencephalopathy

These are diseases of what?
White matter
An alpha-synuclein positive inclusion in an astrocyte is a sign of what?
Multi-system atrophy (MSA)
Mini-gemistocytic oligodendrocytes are a sign of what?
Neoplastic conditions
What is ependymal rosetting a sign of?
Injury
(can be seen in aqueduct stenosis)
MACROglia are derived from what?
ECTOderm
MICROglia are derived from what?
MESOderm
(despite name, these cells are NON-glial)
How long post hypoxic injury do microglia infiltrate?
~ 2 days
From inner --> outermost, layers of meninges
Pia --> Arachnoid --> Dura
("The meninges PAD the brain")
What is the Virchow-robin space?
Tunnel-like extension of the subarachnoid space
Surrounds vessels that pass into the brain or spinal cord
(vessels enter from the subarachnoid space)

Inner wall is pia mater
Outer wall is brain tissue
What layer do large vessels that travel over the brain run through?
Subarachnoid space
What are the two major elements of the BBB?
Endothelial cells
Astrocytes (foot processes around vessels)
What are the two types of cerebral edema?
Vasogenic
Cytotoxic
What is vasogenic edema due to?

What cells are involved?
Disruption of tight junctions between endothelial cells

Expansion of EXTRAcellular compartment

Brain capillaries are involved
What is cytotoxic edema due to?

What cells are involved?
Cellular swelling

Expansion of INTRAcellular compartment

Astrocytes are involved
Flow of CSF
CP --> Interventricular foramen (Monro)
Monro --> cerebral aqueduct
Aqueduct --> lateral/median apertures (Luschka/Magendie)
Apertures --> basal cisterns
Cisterns --> Arachnoid villi --> Venous sinus
Sinus --> Blood circulation
In COMMUNICATING hydrocephalus, what is there a problem in?
Production/Absorption of CSF
In NON-communicating hydrocephalus, what is the problem?
There is an obstruction to the flow of CSF
What is the foramen of Monro?
The connection between a lateral ventricle and the 3rd ventricle
What happens in a subfalcine herniation?
Cingulate gyrus shifts under the falx cerebri
What happens in a transtentorial herniation?
Medial structures are displaced downward through the tentorial hiatus
(often involves medial temporal lobe)

AKA uncal herniation
What happens in a tonsilar herniation?
Cerebellar tonsils get pushed down into the foramen magnum
What CN is most affected by an uncal herniation?
Ipsilateral CN III

Results in mydriasis, ptosis, and lack of pupillary light reaction
What is a duret hemorrhage?

What is the result of one?
Tearing and bleeding of the basilar artery
(due to downward herniation)

These are usually fatal

Deck Info

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