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

Malformations

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