Exam 3 Flashcards
1
Q
encehpalo
A
brain
2
Q
myelo
A
spinal cord
3
Q
polio
A
grey matter
4
Q
leuko
A
white matter
5
Q
Why are neurons non-dividing permanent cells?
A
Don’t have centrioles, thus can’t divide
6
Q
Neuronal regeneration after injury
A
Regeneration as long as cell body intact
Regeneration is better in PNS vs. CNS
7
Q
Types of glial cells
A
Microglia - resident CNS macrophages
Macroglia - astrocytes (structural), oligodendrocytes (myelinate like schwann cells of PNS)
8
Q
Anterograde NT movement
A
- facilitated by kinosin
- away from nucleus toward synapse
9
Q
Retrograde NT movement
A
- facilitated by Dynein
- from synapse toward nucleus (e.g. rabies)
10
Q
White vs. grey matter locations of cerebrum & spinal cord
A
cortex is grey matter (on periphery)
corona radiata is white matter (towards middle)
11
Q
Histo signs of neuronal damage
A
- swollen or shrunken (dying) axons
- chromatolysis, cell body enlargement
- Ischemic cell change
- satellitosis (increased glial cells), neuronphagia
12
Q
Chromatolysis
A
swollen nerve cell body (perikaryon)
w/ loss of nissel substance, displaced nucleus (dispersion)
13
Q
Ischemic cell change
A
angular neurons w/ clear surrounding spaces (b/c retracting from neuropil)
hypereosinophilic
pyknotic (dark) nuclei
+/- edema
14
Q
neuropraxia
A
loss of neural function but no accompanying organic lesions
15
Q
axonotmesis
neurotmesis
A
axonotmesis - axon damaged but myelin sheath is preserved
neurotmesis - entire nerve severed
16
Q
“wear & tear” pigment
A
- accumulation of lipofuscin - orange/brown pigment
- inert change occuring w/ aging
17
Q
intracytoplasmic negri bodies
A
Rabies
18
Q
Virus with just intranuclear inclusion bodies
A
Herpes
19
Q
Virus w/ intracytoplasmic and intranuclear inclusion bodies
A
Canine distemper (morbilivirus) Paramyxoviruses
20
Q
Cytoplasmic vacuolization
A
Prion dz
21
Q
Astrocyte reaction to injury
A
astrocytosis (hyperplasia)
astrogliosis (reactive astrocytes, just processes get enlarged)
gemistocyte - enlarged astrocytes
22
Q
Oligodendrocyte reaction to injury
A
- hydropic swelling
- hypomyelination (myelin is pale, conduction slow)
- status spongiosus - cavitated myelin
- May see remyelination or permanent demyelination
23
Q
Microglia (macrophages) reaction to injury
A
microgliosis (hyperplasia)
microglial nodules (groupings) - perivascular cuffs if around vessel
“gitter cells” - phagocytically active
24
Q
Schwann cell reaction to injury
A
CNS - wallerian degeneration and/or regeneration
PNS - hypomyelination, demyelination
25
What happens when the brain swells
Swelling --> compression of bv's --> BBB compromise, rupture --> hemorrhagic stroke (more common)
vessel occlusion --> ischemic stroke
Edema, Herniation
26
Ischemic stroke
thrombus or thromboembolism --> compromise of end arteries (no anastamosis) = entire area of brain loses blood flow, dies
27
how do electrolytes get into the brain
active transport d/t BBB, also affects water regulation
28
what is the hallmark of cerebrovascular dz
sudden loss of neuro function
29
Atherosclerosis
hypothyroid, high dietary fat intake --> hypercholesterolemia --> plaque buildup --> thrombosis, embolism, infarction, ischemic stroke
Cerebral aa. have narrow lumen, yellowish
30
what type of necrosis happens in the brain
liquefactive - b/c majority of components are made of lipids
31
Grossly, how do you evaluate for brain edema?
- shifted midline
- hemispheres not symmetrical
- Gyri more flattened, sulci less deep
32
Edema in the brain
Often d/t trauma
| excess fluid accum in CNS parenchyma --> edema
33
4 different types of edema
Vasogenic
Cytotoxic/cellular
Interstitial/hydrostatic
Osmotic
34
Vasogenic edema
most common type, worst type
usually a trauma, mass, inflamm, hemorrhage
bbb compromise or trauma --> vascular injury --> fluid accum EXTRAcellularly in cerebral WHITE matter
35
Cytotoxic/cellular edema
usually less severe, most commonly d/t ischemia & hypoxia
na/k pump failure --> ionic disruption --> INTRAcellular fluid accum in both white AND grey matter
36
Interstitial/hydrostatic edema
increased ventricular pressure --> ependymal barrier breach --> fluid accum in periventricular white matter
37
Osmotic edema
protein loss in blood (via GI, kidney, skin) --> hypoosmolar plasma --> intracellular but some extracellular fluid accum
38
What types of edema usually result in herniation?
vasogenic
| cytotoxic
39
Places the brain can herniate
- cerebellar vermis through foramen magnum
- through tentoial notch (btwn cerebrum & cerebellum)
- parahippocampal gyral herniation under falx cerebri
40
How is trauma to the skull described
plane of trauma
mechanism of trauma
where hemorrhage will develop
41
Planes of trauma
axial - head on
angular - to L or R (most common)
rotational - while rolling, multiple places damaged
42
coup hemorrhage
hemorrhage develops at site of impact
| e.g. fall and hit head
43
contrecoup hemorrhage
hemorrhage develops opposite site of trauma, e.g. blow to head
44
epidural hemorrhage
meningeal a. damage = hemorrhage above dura (most external CT layer)
45
cortical hemorrhage
hemorrhage in cortex
46
subcortical white matter hemorrhage
hemorrhage deeper than cortex
47
subdural hemorrhage
hemorrhage btwn dura and leptomeninges (arachnid + pia mater)
48
subarachnoid hemorrhage
hemorrhage underneath arachnoid layer
49
deep intracerebral hemorrhage
worst kind, deepest hemorrhage
50
concussion
temporary loss of consciousness - mental process affected
51
contusion
brain bruising, usually assoc'd w/ blood vessel rupture, trauma
52
common fracture when horses rear over backward
- basisphenoid fracture
- lacerates cerebellar and vertebral aa.
- hemorrhage dominant lesion, may affect brainstem, can die quickly
53
Hansen type 1 spinal cord trauma
rapid annulus rupture --> sudden pain/paresis, maybe death
| hemorrhage likely visible
54
Hansen type 2 spinal cord trauma
- more common
- weakening annulus --> slow bulge --> chronic compression of cord
- white matter lesion only (wallerian degen of axons)
- animal has chronic painful back, proprioceptive deficits, decreased pain perception
55
Wallerian degeneration aka secondary demyelination
- white matter lesion
- axons constricted, myelin breaks down
macrophages degrade myelin, spaces left are "digestion chambers"
- axonal damage occurs before myelin degeneration
- see accum of galactocerebroside & psychosine
- hansen type II spinal dz, copper in pigs
56
What nervous system components are most sensitive to ischemia? Least?
- neurons, oligodendrocytes (grey matter) - most
- astrocytes - moderately
- microglia, b.v. - fairly resistant
57
Dz's that cause primary focal cerebrovascular dz
- atherosclerosis
- fibrocartilaginous embolism in spinal cord causing hansen type 1 embolus
- feline ischemic encephalopathy
58
feline ischemic encephalopathy
- cuterebra larvae migration
| - see vessel necrosis, edema, gitter cells on histo
59
DZ's causing multisystemic cerebrovascular dz
- vascular wall dz
- intravascular (thombi, emboli)
- global cardiac ischemia d/t cardiac arrest
60
Viruses causing vascular wall dz
```
SHV (suid)
IBR
EHV 1 & 5
MCF (malignant catharral)
EVA (EQ viral arteritis)
FIP - pyogranulomatous inflamm around vessels
```
61
Malacic/nutritional diseases
PEM
Salt poisoning
Nigropallidal encephalomalacia
Mycotoxic leukoencephalomalacia (moldy corn)
62
PEM (polioencephalomalacia)
softening of deep lamina of cerebrocortical grey matter in cattle, sheep, goats
63
Causes of PEM
- Thiamine deficiency (heat, thiaminases (plants/meat), or diet insufficiency)
- sulfur/sulfate being reduced by bacteria causing ATP depletion, cell death
64
How does thiamine (B1) deficiency differ in carn vs. rum
carn - midbrain/brainstem nuclei dz, usually diet deficiency (caudal colliculi, periventricular nuclei)
rum - cerebrocortical grey matter
65
gross signs of PEM
- swollen, edematous, necrotic areas are discolored yellow, bilateral dz
- dead grey matter will fluoresce under a Wood's lamp
66
clin signs of PEM
bilateral vestibular dz - animal can't right self
| vs. circling is unilateral dz
67
salt poisoning
- pigs
- water deprivation + high salt diet --> hypernatremic/hypertonic blood dehydrates brain, slow to equilib
- water returns, blood becomes hypotonic, dilutes sodium --> cns dehydration, cerebral and osmotic edema
68
clin signs
sitting like a doggo, head drawn up
69
Gross lesions of salt poisoning
herniation, moderate edema/swelling
70
histo lesions of salt poisoning
edema
laminar cortical necrosis
eosinophilic meningoencephalitis
71
nigropallidal encephalomalacia
EQ
- softening of substantia nigrus, globus pallidus --> bilateral caviation
- prolonged, high % ingestion of yellow star thistle or russian knapweed (often in a dry summer)
72
mycotoxic leukoencephalomalacia (aka moldy corn poisoning)
poorly stored corn = fungus growth
| mycotoxins --> swelling, softening, hemorrhage of subcortical white matter
73
Things that affect grey matter
Thiamine deficiency
Sulfur or lead toxicity
salt poisoning
74
4 Main molecular level insults to the brain
Acidosis
Free radical formation
Apoptosis
Excitotoxicity
75
Excitotoxicity
overactivation of glutamate receptors --> constant depolarization --> high Ca into cells, excess E --> excess enz activation --> cell structure damage ---> neuron damage and death
76
Causes of excitotoxicity
```
stroke
traumatic brain injury
CNS neurodegenerative dz
hypoglycemia
status epilepticus
```
77
4 portals of pathogen entry into the CNS
Hematogenous - most common
Direct Extension
Leukocyte trafficking (retroviruses)
Retrograde axonal transport (rabies)
78
Examples of hematogenous entry
```
Thrombotic meningoencephalitis (TME) - bov
Polyserositis - pigs
C. pseudotb - sheep
```
79
Examples of direct extension entry
- penetrating trauma - mid/inner ear infections, osteomyelitis, sinusitis
- mycoplasmosis in cows
- pasteurellosis
80
signs of acute bacterial infection
suppurative encephalitis, myelitis, encephalomyelitis
81
signs of chronic bacterial infection
caseous necrosis, CT capsule formation
82
Listeriosis/circling dz (L. monocytogenes)
sheep, often <3 yo
brain stem lesions (adults - encephalitic form)
head tilt, circling
83
4 forms of Listeriosis
abortive
ocular
systemic infection
nervous
84
Histo signs of listeriosis
microabscesses
perivascular cuffing
stain purple on gram stain
85
Thrombotic meningoencephalitis (H. somni)
birds, bovids
| vasculitis AND thrombosis --> vascular necrosis in cerebrum, lungs, heart, larynx
86
Characteristics of viral encephalitis
perivascular cuffing, glial nodules
gitter cells, reactive astrocytes
neuronphagia, demyelination
inclusion bodies
87
Signs of Equine encephalitis infection
vasculitis, thrombosis
polioencephalomyelitis (grey matter softening of brain and spinal cord)
neutrophilic reaction
88
Signs of fungal encephalitis
pyogranulomatous to granulomatous inflamm w/ intrahistiocytic organisms
89
Protozoa that cause neural infection
Sarcocystis neurona
Neospora caninum
Toxoplasma gondii
90
Sarcocystis neurona
EPMyelitis/myeloencephalitis
opossums - definitive host, EQ - dead end host
non-suppurative asymmetric spinal cord lesions - cervical and lumbar enlargements
91
Neospora caninum
- multisystemic infection --> multifocal infarctions, abortion
- brain, heart, kidneys of fetus
- dogs intermediate hosts, EQ/rum ingest
- banana shaped organisms
92
Causes of myelinopathies
BVDV, border dz/pestiviruses, ovine progressive pneumonia, canine distemper
93
Primary demyelination
Removal of normal myelin by macrophages d/t inflammatory response, then axon degenerates
94
Dz's that cause primary demyelination
canine distemper
visna (sheep) & caprine arthritis encephalitis
coonhound paralysis
globoid cell leukodystrophy (krabbes-like dz)
95
GCLD (globoid cell leukodystrophy)
abnx storage of galactocerebroside & psychosine in oligodendrocytes & schwann cells --> primary demyelination
96
prosencephaly
abnx closure of rostral neural tube = anterior brain doesn't form
97
porencephaly
- Cyst/cavity in cerebral hemisphere of brain separate from ventricular system
- Can progress to hydraencephaly
98
Lissencephaly/agyria
- cerebral hemispheres are smooth possibly d/t neurons not migrating during development
- lab animals & poultry don't have sulci/gyri normally
99
cerebellar hypoplasia
usually viral etiology - in utero infection w/ canine parvo, feline panleuko/parvo, pestiviruses (BVD, CSF)
100
hydrocephalus
- ependymal cell and choroid plexus cell issues = increased fluid accum, increased ICP
- if in utero, dome calvarium at birth
101
hydrocephalus is usually congenital, what is one acquired cause?
intrauterine infection of bluetongue in lambs --> hydraencephaly (end stage of hydrocephalus)
102
Cereoid-lipofuscinosis
storage dz causing bronze-colored brain
| Tibetan terriers
103
most common brain tumor in cats
meningioma, space-occupying & assymetric
| high grade = hemorrhage
104
2 metastatic tumors causing brain lesions
hemangiosarcoma
| mammary carcinoma
