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