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Pathologic Responses of the Nervous System
GROSS CHANGES
Finding the lesion
Gross artefacts
Gross lesions
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HISTOLOGIC REACTIONS OF CELLS
Reactions of Neurons
• swelling and shrinkage
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Reactions of Neurons
• satellitosis
• neuronophagia
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Reactions of Neurons
• chromatolysis
• ischaemic nerve cell change
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Reactions of Neurons
neurapraxis - loss of function only
axonotmesis - damage to axons with
preservation of myelin
sheaths
neurotmesis - severance of entire nerve
fibre
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Reactions of Neurons
wallerian degeneration and regeneration
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Reactions of Neurons
wallerian degeneration and regeneration
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Reactions of Neuronsswollen axons, spheroids,
neuroaxonal dystrophy
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Reactions of astrocytes
hyperplasia and
hypertrophy
reactive astrocytes
fibrillary
astrogliosis
gemistocytes
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Reactions of oligodendrocytes hydropic swelling
hypomyelination
status spongiosus
demyelination
remyelination
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Reactions of microglial cellsmicrogliosis
perivascular cuffs
microglial nodule/’star’
gitter cells
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Reactions of Schwann cells
wallerian degeneration and regeneration in PNS
hypomyelination and demyelination
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Mechanisms of Neuropathology
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Malformations
physicalinfectious
toxic
genetic
multifactorial
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Infectious, Inflammatory, Immune
a. Viral
b. Bacterial
c. Fungal
d. Protozoal
e. Heiminth
f. Immune
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space-occupying lesions and herniation
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Toxic Diseases
symmetrical
diffuse
selective
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Nutritional Diseases
deficiencies
symmetrical
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Metabolic Diseases
electrolytes
glucose
organ failure
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Metabolic Diseases
inherited defects, especially:
neuronal abiotrophies [‘lack of trophic factors’]
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Metabolic Diseases
inherited defects, especially:
lysosomal storage disease
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Vascular Lesions
per-acute
infarction
emboli and thrombi
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Neoplastic Diseases
brachycephalic dogs
CNS - glial and meningeal tumours
PNS - Schwann cell tumours
secondary and axial tumours
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Neoplastic Diseases
invade, replace or compress tissue
space-occupying effect