Block 4 PATH Exam -- Intro to Neuropathology
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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