Nervous system pathology 2 Flashcards
Name some examples of CNS vascular lesions
- Ischaemic brain infarct
- Ischaemic encephalopathy
- Haemorrhagic brain infarct
- Haematoma
- Feline hypertensive encephalopathy
Define Atherosclerosis
Thickening or hardening of arteries
Which vascular condition affects the spinal cord?
Embolic encephalomyelitis
What are the clinical and diagnostic hallmarks of CNS vascular lesions?
Diagnostic hallmark: Focal or non-symmetrical multifocal haemorrhagic or malacic lesions
Clinical Hallmark: Acutely developing neurological symptoms without appreciable progression
Which features of the CNS make it susceptible to ischaemia?
- High metabolic request (one third of total glucose)
- Impossibility for local storage (e.g. glycogen)
- Ischemia starts after 60% decrease of blood flow
What is the order in which the cells of the CNS are most susceptible to ischaemia?
Neurons > oligodendrocytes > astrocytes > microglia and endothelial cells
A few minutes of hypoxia leads to?
Neuronal cell death
What are the two ways that reduced oxygen levels reach the brain?
- Ischaemia: reduced flow of normally oxygenated blood
- Hypoxia: normal flow of poorly oxygenated blood
What are 3 causes of an ischaemic brain infarct?
- Vascular thrombosis
- Emboli (e.g. mitral valve endocarditis, tumour emboli)
- Intracarotid injection (horses)
How will the grey and white matter appear in an acute infarct infection?
Grey: hyperaemia and astrocytosis
White: rale area with ‘red neurones’ and spheroids
What is astrocytosis?
An abnormal increase in the number of astrocytes due to the destruction of nearby neurons from central nervous system (CNS) trauma, infection, ischemia, stroke, autoimmune responses or neurodegenerative disease.
How will the grey and white matter appear in a chronic infarct infection?
Grey: glial scar formation
White: liquefactive necrosis and astrogliosis
Under histology what does a ‘rusty’ colour represent?
Haemosiderin
What is the cause of hemosiderin being found in the CNS?
Accidental injection into arteries e.g. carotid, causing inflammation of vessels (phlebitis)
How will infarction in the spinal cord appear grossly?
Bruise like appearance – haemorrhage and necrosis of consecutive sections
If fibrocartilaginous material is seen within the lumen of small arteries what lesion will occur?
Fibrocartilaginous embolism
Which vascular condition is extremely common in horses?
Siderocalcinosis of vessels
What are 5 methods of infectious agents reaching the brain?
- Deposition of immune complexes e.g. FIP
- Direct infection of endothelial cells
- Local accumulation of bacterial within vessels and consequent suppuration
- ‘Trojan horse’ mechanism
- Retrograde axonal transport
Which different agents cause inflammation?
- Virus
- Bacteria
- Parasites
- Mycotic
- Idiopathic
- Autoimmune
What are the different inflammatory patterns seen in the CNS?
- Suppurative
- Non-suppurative
- Eosinophilic
- Granulomatous
- Polioencephalitis
- Leukoencephalitis/ demyelination
How does a gross CNS inflammatory lesion appear?
Malacic (softening), haemorrhagic, firm (granulomatous) and variably demarcated
What is the specific term given to inflammation of the following anatomic locations:
- Brain
- Spinal cord
- Encephalitis
2. Myelitis
What is the specific term given to inflammation of the following anatomic locations:
- Grey matter of the brain
- Grey matter of the brain and spinal cord
- White matter of the brain
- White matter of the brain and spinal cord
- Polioencephalitis
- Polioencephalomyelitis
- Leucoencephalitis
- Leucoencephalomyelitis
What is the specific term given to inflammation of the following anatomic locations:
- Leptomeninges and brain
- Dura mater
- Choroid plexus
- Meningoencephalitis
- Pachimeningitis
- Choroiditis
What are the major morphological hallmarks of a viral infection in the CNS?
- Perivascular cuff
- Non-suppurative inflammatory pattern
- Often selectively targeting neurons or specific neuronal subpopulations (polioencephalitis/-myelitis)
- Frequent involvement of meninges and choroid plexuses
What is a perivascular cuff?
- Accumulation of extravasated inflammatory cells within the perivascular space (Virkow-Robin space)
- In the early stages this perivascular cuff is not inside the CNS because of the pia matter and meninges where the vessels are outside of these
How does a purkinje neurone appear?
One cell thick layer of the large, flame shaped neurones
Dark purple staining cells in the cerebellum are?
Granules
What is the inflammatory pattern shown by rabies?
Mild non-suppurative polioencephalomyelitis (within the grey mater)
Where does rabies virus travel in the body?
Inoculum site -> muscle -> axons -> CNS!
What are the characteristic cells seen in Rabies infections?
Pathognomonic presence of eosinophilic round intracytoplasmic inclusions (Negri’s bodies in the cytoplasm of piramidal neurons of the hippocampus, carnivores, and Purkinje cells, ruminants, of the cerebellum)
What are the 3 serial clinical phases of a rabies infection?
Prodromic, excitatory and paralytic
What is the other form of Rabies?
Furious form
Describe the inflammatory pattern of Canine distemper virus
Demyelinating leukoencephalitis (primary demyelination)
Describe the 2 pathological stages of Canine distemper virus infection
Acute: pale demyelinated areas (gliosis and macrophages )
- Chronic: Non-suppurative inflammation with evident cavitation
Describe post-vaccinal distemper
A non-suppurative polioencephalitis with abundant inclusion bodies occurring 2 weeks after CDV vaccination
Which species is most commonly infected by West Nile encephalitis?
Horses
What is the inflammatory pattern in West Nile encephalitis?
Non-suppurative Polioencephalomyelitis
Which region is most specifically affected by West Nile encephalitis?
Grey matter of the thoraco-lumbar spinal cord
Which histological changes can be seen in West Nile encephalitis
Within the grey matter
inflammatory cells accumulate around vessels
They migrate in the direction of CNS to infect neurones
Which CNS virus most commonly affects sheep?
Maedi-visna virus
Describe the inflammatory pattern of Maedi-visna virus
Granulomatous leukoencephalomyelitis
- Inflammation of the brain and spine
- Rich in macrophages
What other pathological features are also observed with Maedi-visna?
- Chronic lymphoplasmacytic infiltration (Granulomatous appearance)
- Cavitation and malacia are frequently observed
- Choroiditis and meningitis are commonly observed
