Neuropathology: Infection and Inflammation Flashcards
What forms the blood-brain barrier?
brain microvascular endothelial cells, astrocytes and pericytes
What is the function of the blood brain barrier?
maintains the neural microenvironment by regulating the passage of molecules into and out of the brain and any microorganisms/ toxins circulating in the blood
What is the haematogenous spread of infection?
Bacteria with a direct cytotoxic effect on endothelial cells on the BBB
What is the retrograde spread of infection?
Spread along axons of olfactory neurons or axons of the peripheral/ cranial nerves
What does bacterial infection pathology usually look like?
usually charcterised by neutrophils
What is the most common meningitis?
leptomeningitis
What is meningitis most common in?
neonatal pigs, lambs, calves, goat kids and foals
What may a space occupying lesion lead to?
cerebellar coning
What is the name of a bacterial disease that can spread systemically and cause bacteraemia/ septic embolism that can then spread to the brain
purulent encephalitis/ malacia
When does septic embolism/ thromboembolism to the brain occur?
May occur in severe bacteraemia when the blood swarms with bacteria
What is the outcome of septic embolism
Cerebral abscess
Cerebral infarcts
What bacteria causes thrombotic meningoencephalitis?
Histophilus somni (Gram-Neg coccobacillus)
What does thrombotic meningoencephalitis look like grossly?
multifocal haemorrhage on the surface and cut sections of the brain
What does thrombotic meningoencephalitis look like microscopically?
Haemorrhages and thrombosis with neutrophillic infiltrates
What is the listeriosis route of infection?
Trigeminal neuritis
* penetrates damaged oral mucosa
* ascends the axons of the trigeminal nerve
* unilateral microabscessation in the medulla oblongata with inflammation
What are the CNS features of canine distemper?
- Non-Suppurative encephalitis
- Demyelination
- Secondary gliosis
- inclusion bodies (cytoplasmic and nuclear)
What are the 4 main routes of infection?
- Haematogenous
- Retrograde Spread
- Direct Implantation
- Direct Spread of Infection from other sites
What is encephalitis?
Inflammation of the brain
What is Myelitis?
Inflammation of the spinal cord
What is Encephalomyelitis?
Inflammation of the brain and spinal cord
What is ependymitis?
Inflammation of the ependyma
What is choroiditis?
Inflammation of the choroid plexus of the ventricles
What is meningitis?
Inflammation of the meninges
What is leptomeningitis?
Inflammation of the leptomeninges
What is pachymeningitis?
Inflammation of the pachymeninges
When may a septic embolism occur?
Severe bacteraemias when the blood swarms with bacteria
outcome = septic abscess or cerebral infarct
What bacteria causes Thrombotic Meningoencephalitis?
Histophilus Somni
What is the pathogenesis of listeria monocytogenes?
- Penetrates the damaged oral mucosa
- ascends axons of the trigeminal nerve
- causes trigeminial neuritis and ganglioneuritis
What is the function of microglia?
- Resident phagocytes
- Similiar to macrophages- removal of individual neurons
What do astrocytes react to?
They react non-specifically to many stimuli
What are the four main routes of infection?
- Haematogenous
- Retrograde spread
- Direct implantation
- Direct spread from other sites
What is encephalitis?
Inflammation of the brain
What is myelitis
inflammation of the spinal cord
What is encephalomyelitis?
inflammation of the brain and spinal cord
What is the portal of entry of meningitis bacteria
E.coli, Pasteurella, Streptococcus, Salmonella
- Oropharyngeal
- Respiratory
- Umbilicus
- Superficial wounds
What are the usual histological features of Viral Infections?
- Neuronal necrosis
- Chromatolysis
- Inclusion bodies
What are three ways viruses reach the CNS
most are part of systemic infections
- Systemic infection
- display neurotropism
- Reach teh CNS haematogenously
- Peripheral nerves e.g rabies
- Extension from the nasal cavity to the brain
Name three equine viral diseases
- Bornavirus
- West Nile Virus
- Herpesvirus
What is the pathogenesis of tachyzoites?
- they reach the CNS via the bloodstream
- Intracellular replication
- haemorrhage and inflammation
What is granulomatous meningoencephalitis?
- T-medaited delayed-type hypersensitivity reaction
- occurs in toy poodles and terriors
Necrotisisng meningoencephalitis
non-infectious encephalitides
- occurs in pugs, maltese and chihuahua
- autoimmune disease
- grey matter of the cerebral cortex
What is the pathogenesis of thrombotic meningoencephalitis?
- Bacterial lipoligosaccharides interact with platelets and endothelial cells-> causing vasculitis, thrombosis and septic infarct
What does listeriosis cause in the medulla oblongata?
- microabscesation
- inflammation of the overlying leptomeninges#
- extension into the adjacent pons/ cranial cervical spinal cord
