L8: Path of the Nervous System 2 (Farina) Flashcards
BBB endothelial cells connected by:
tight junctions and adherens junction proteins
properties of BBB endothelial cells
- have fewer endocytic vesicles (less transcellular flux)
- rich in efflux transport proteins to transport harmful material back into the blood
neurotropism
ability of organisms to breach the BBB and Blood-CSF Barrier
inflammatory conditions
meningitis encephalitis myelitis meningoencephalitis ( meningomyelitis meningoencephalomyelitis
chars. of bacterial infections
- most commonly 2ary to septicemia** in young animals
- septic emboli w/endocarditis
- abscesses from hematogenous spread or direct invasion (usually through cribiform plate or from middle ear**)
Listeriosis
“circling disease”
- usually in ruminants
- outbreak usually assoc. with heavy feeding of silage**
- CS: head tilt, circling, confusion, depression, head pressing, unilateral facial n. paralysis, masticatory m. paralysis, purulent endophthalmitis
- usually septicemic in young animals, neurologic in adults
- lesions most common in brainstem**
- bacteria spread up motor and sensory br. of trigeminal n.
- usually no gross lesions; microabscess on histo
Infectious Thrombotic Meningoencephalitis (ITME)
- caused by Histophilus somni** (which is normally found in upper GI/resp/urogenital tracts in healthy animals!)
- affects cattle and sheep
- septicemia –> cerebral vasculitis w/ hemorrhage, necrosis, thrombosis, neutrophilic meningoencephalitis
Characteristic appearance of viral infections**
-non-supparative meningoencephalitis (+/- myelitis)
-perivascular cuffing
-gliosis
+/- viral inclusions
+/- neuronal degeneration/necrosis
Rabies
- skunks, fox, raccoons, bats principal reservoir in US
- exhibits tropism for the CNS and salivary gland
- replicates in m. cells near inoculation site, spreads to paravertebral site, travels along peripheral nerves to CNS
- lesions: nonsuppurative encephalomyelitis, gangioneuritis, parotid adenitis; variable inflamm. and neuronal degeneration
- Negri bodies (cytoplasmic inclusion) usually found in hippocampus of carnivores and Purkinje cells of herbivores
Pseudorabies
- caused by herpesvirus-1
- affects all common domestic species**
- spread b/w pigs: contact of virus-infected secretions from skin/nasal mucosa
- spread to carnivores from eating infected pig meat
- spreads from site of inoculation –> nerve –> spinal cord –> CNS –> peripheral nerves
CS of pseudorabies in species other than pigs
“mad itch”
high mortality rate
fever
neuro signs
CS of pseudorabies in pigs
mild fever, NO pruritus
Young pigs: convulsion, m. tremor, prostration
Sows: abortion, stillbirth, mummies
EEE, WEE, VEE, SLE are all what type of virus
arbovirus
-horses most commonly infected
trans. of arboviruses**
mosquito
arbovirus lesions
lymphohistiocytic/neutrophilic polioencephalomyelitis gliosis neuronal degradation/necrosis vasculitis meningitis thrombosis WNV: NONsupparitive, EEE supparitive
Lentiviruses - Caprine arthritis encephalitis (CAE) virus
- neuro signs in 2-4mo. kids**
- CS: hind limb ataxia, paresis/paralysis, death
- lesions: non-suppurative leukoencephalomyelitis, demyelination
- adults can get arthritis, mastitis, pneumonia
Lentiviruses - Visna-maedi virus
- sheep >2yo**
- CS: hindlimb ataxia, lip trembling, hindlimb paralysis. Death 2ary to infection or starvation
- lesions: nonsuppurative meningoencephalitis of white matter, demyelination
- can cause pneumonia, mastitis, arthritis
Canine Distemper Virus
- morbillivirus
- affects canids, procyonids, mustelids, some large cats
- perivascular cuffing, +/- hyperkeratosis of foot pads
- intranuclear/intracytoplasmic inclusions
Equine Herpesviral Myeloencephalopathy
- EHV-1 or 4
- spread by inhalation of nasal aerosols, contact w/ infected fetus/placenta, direct contact
- replicates in endothelial cells, causes thrombo-occlusive, necrotizing vasculitis
- gross lesions: none, or foci of hemorrhage in brain
- non-suppurative necrotizing vasculitis/thrombosis
fungal infections usually 2ary in immunocompromised patients
:)
only fungus with a real predilection for the CNS**
Cryptococcus neoformans
- usually starts as nasal or sinus infection
- dogs, cats, horses
- grossly: grey, gelatinous foci in brain and meninges
- histo: non-staining mucopolysaccharide capsule** w/ “soap bubble” appearance; +/- inflammation
Equine Protozoal encephalomyelitis
- Sarcocystis neurona**
- sporocysts ingested, multiply in viscera, transported to CNS
- usually no gross lesions
- histo: hemorrhage, necrosis, perivascular cuffs of lymphos/macs/neuts/eos/astrocytosis
Toxoplasmosis
- affects variety of mammals including monkeys
- often seen with immunosuppressed**
- gross: hemorrhage, necrosis
- histo: hemorrhage, necrosis, cuffing, tachyzoits and cysts containing bradyzoites
Transmissible spongiform encephalopathies (TSEs)
- caused by prions, abnormal isoforms of prion protein**
- abnormal isoforms of prion protein act as template for refolding prion protein
- horizontal trans.** via consumption of infected feed
- Examples: BSE, Scrapie, CWD, FSE, Transmissible mink encephalopathy
- lesions: intracytoplasmic neuronal vacuolization, astrocytosis
Meningioma
- cats, dogs, horses, cattle, sheep
- tumor on meningeal surface of CNS
- well-demarcated, encapsulated, expansile
Astrocytoma
- dogs (esp. brachiocephalics**), cats, cattle
- POORLY demarcated, firm
- in white and grey matter
- most commonly affects pyriform and temporal lobes
Oligodendroglioma
- dogs (esp. brachiocephalics*), cats, cattle
- soft/gelatinous mass in white or grey matter of cerebrum and brainstem
