CNS 1, 2 and 3 Flashcards
What is the falx cerebri?
What is the cerebellar vermis?
What is the olfactory bulb?
What is the tentorium cerebelli?
The central fold of the brain- sulcus
Falx cerebri- central area of fold- sulcus
Cerebellar vermis- most caudal part of the brain
Olfactory bulb- front of brain- rostral
Tentorium cerebelli- fold between cerebellum and rest of brain
What is the telencephalon?
What is the mesencephalon
What is the diencephalon?
Telencephalon- cerebral cortex and basal nuclei
Mesencephalon- periaqueductal grey matter
Diencepalin- hippocampus and thalamus
What kind of neurons are in the dorsal and ventral horns of the spinal cord?
What surrounds the central grey matter?
Dorsal- grey matter- sensory
Ventral- grey matter- motor
White matter surrounds
What does this image show?
What is its function of it?
Choroid plexus
Produces CSF
What lines the ventricular system?
How many ventricles is it made up of?
What is and what is the function of CSF?
Lined by ependyma
four communicating ventricles each with a choroid pleuxus
CSF- blood ultrafiltrate continuously produced within ventricles drained by the saggital sinus
CSF acts as a cushion and provides nutrients to neuroparenchyma
Which of the following cells do not belong the CNS?:
- Oliogodendroglia
- Microglia
- Ependyma
- Schwaan cells
- Astrocytes
Schwaan cells
What are neurons structurally composed of?
Large nucleus with a prominent nucleus
Soma or perikaryon with prominent RER
Dendrites- multiple receiving information from myriad
Axon- single, projecting signal from the soma to the effector cell
High variation in shape and dimension
What is the purposes of astrocytes?
- Creation and maintenance of the integrity of the BBB
- Uptake and recycling of neurotransmitters
- Maintenance of extracellular pH and osmotic pressure
- Supporting metabolic demands of neurones
- Supporting migration of neurons during neurogenesis
- Protoplasmic and fibrillar
- Express GFAP as intermediate filament
How do oligodendrocytes appear?
Small cells with round picnotic nucleus
Interfascicular (white matter) and satellite oligodendrocytes (grey)
Responsible for production of myelin in CNS
Long and complex membrane projection to compose myelin sheaths
In H and E surrounded by clear halo (lipids)
Schwann cells- PNS
What are microglia?
What is their function?
Resident macrophage-like cells in the CNS
12% of cells
Active immune surveillance
What are the layers of the head from bone to brain?
- Bone
- Dura mater- thick and rich in collagen
- Arachnoid
- Pia mater- thin later
- Brain
What is malacia?
What is neuropil?
What is satellitiosis?
Malacia- necrosis of the CNS
Neuropil- area of nervous system composed mostly of unmyelinated axons
Satellitosis- abnormal clustering of one type of cell around another
Why are neurons susceptible to damage?
- Stable, full of developed and extremely specialised cells
- Lack of proliferating activity
- High metabolic demands
- Low capacity of ‘metabolic adaptation’
- The majority of neurons extend their processes far from perikaryon
How do neurons become damaged and how do they react?
Neuron damage-
Excitotoxicity- leads to red hypoxic neurons
Oxidative stress and decreases antioxidants
Reaction-
- Chromatolysis
- Red dead neurons
- Apoptosis
- Intracytoplasmic accumulation
- Vacuolation
- Intranuclear and intracytoplasmic inclusions
What is astrogliosis and astrocytosis?
How do astrocytes respond to damage?
Astrogliosis- increase in number- hypoplasia
Astrocytosis- increase in cell volume- hypertrophy
Cell swelling, cell hypertrophy, scar tissue formation
What happens when oligodendrocytes are damaged?
Damage alters the cell membrane and causes-
impaired function or defective myelin formation- primary demyelination
myelin destruction and phagocytosis- secondary demyelination
What are the different types of CNS oedema, what causes them and what is their outcome?
Cytocxic-
cause- altered cellular metabolism
outcome- intracellular accumulation of fluid
Vasogenic-
cause- vascular injury with a breakdown of the BBB
outcome- extracellular accumulation of fluid- cerebrocortical white matter
Hydrostatic-
cause- elevated ventricular hydrostatic pressure
outcome- extracellular accumulation fluid
Hypo-osmotic
cause- osmotic imbalances plasma v extracellular, microenvironments
extracellular and intracellular accumulation of fluid
What are the different vascular lesions that can affect the CNS?
- CNS-
- Ishaemic brain infarct
- Ishaemic encephalopathy
- Feline ishaemic encephalopathy
- Haemorrhagic brain infarct
- Haemorrhage/haematoma
- Feline hypertensive encephalopathy
- Atherosclerosis
- Oedema
- Siderocalcinosis of a vessel wall
- Feline ishaemic encephalopathy
- Spinal cord
Why is the CNS highly susceptible to ischaemia?
- High metabolic request
- Impossible local storage of glycogen
- Ishaemia starts after 60% decrease in blood flow
- Can be global or local
A few minutes of hypoxia can lead to neuronal cell death
What can cause an ischaemic brain infarct?
How do they appear acutely and chronically?
Vascular thrombosis, emboli, intracarotid injection (horses)
Acute infarction- penumbra of hyperaemia and astrocytosis with a central area of ischaemia with the pale area with red neurons and spheroids
Chronic infarction- penumbra of glial scar formation with centre of liquefactive necrosis and astrogliosis
How do infectious agents reach the brain?
What are the different types of inflammatory patterns?
- Deposition of immunocomplexes- FIP
- Direct inflammation of endothelial cells- classical swine fever
- ‘Trojan horse’ mechanism- virus, toxoplasma
- Local accumulation of bacteria within vessels and consequent suppration
- Retrograde axonal transport- listeria
Inflam patterns-
Suppurative/non-supprative
eosinophilic,
granulomatous
polioencephalitis
leukoencephalitis
What do the following inflammations affect?:
- Encephalitis
- Myelitis
- Polioencephalitis
- Polioencephalomyelitis
- Leucoencephalitis
- Leucoencephalomyelitis
- Meningoencephalititis
- Pachimeningitis
- Choroiditis
- Encephalitis- brain
Myelitis- spinal cord - Polioencephalitis- grey matter of the brain
- Polioencephalomyelitis- grey matter of the brain and spine
- Leucoencephalitis- white matter of the brain
- Leucoencephalomyelitis- white matter of the brain and spine
- Meningoencephalitis- leptomeninges and brain
- Pachimeningitis- inflammation of the dura mater
- Choroiditis- choroid plexus
What is a perivascular cuff?
Accumulation of extravasated inflammatory cells within the perivascular space
How are viral lesions distributed and what is their inflammatory pattern in the CNS?
Inflammatory pattern-
non-supprative with frequent formation of neuruonphagic nodules
Distribution-
often selectively targeting neurons or specific neuronal subpopulations (polio encephalitis/myelitis)
frequently involve meninges and choroid plexus
What type of virus is rabies?
What is its CNS inflammatory pattern?
What is its inoculum site?
What inclusion bodies does it cause and where?
What do they tell you about the inflammation?
What are the three clinical phases?
RNA- Rhabdoviridae lyssavirus
Inflammatory pattern- mild non-supprative polioencephalomyelitis- incubation period variable
Inoculum site- muscle- axons- CNS
Pathognomonic presence of eosinophilic round intracytoplasmic inclusoins- negri’s body in the cytoplasm
Frequency of inclusion bodies is inversely proportional to inflammation
Three clinical phases- prodromic, excitatory, paralitic
What is the inflammatory pattern of west nile?
Which area of the CNS is particularly affected?
West Nile- arbovirus
Inflammatory pattern- non-supprative polioencephalomyelitis
Grey matter of the thoracolumbar spinal cord is particularly affected
Lesions extend into the caudal brainstem
What is the inflammatory pattern of canine distemper?
What are the acute and chronic pathological stages?
What is post vaccinal distemper?
Inflammatory pattern- demyelinating leukoencephalitis
Acute- pale demyelinated areas
Chronic- non-suppurative inflammation with evident cavitation
Post vaccinal distemper- non-suppurative polio encephalitis with abundant inclusion bodies occurring 2 weeks after CDV vaccination
Describe the inflammatory pattern seen in this image
What virus causes this in sheep?
Inflammatory pattern- granulomatous leucencephalomyelitis
Visna- maedi-visna virus
Chronic lymphoplasmacytic infiltration- granulomatous appearance
Cavitation and malacia are frequently observes
Choroiditis and meningitis are commonly observed
What kind of virus causes FIP?
How does FIP grossly appear?
What lesions does FIP cause in the eye?
Feline coronavirus
Antibody-antigen immunocomplexes deposit within the vessel wall
Immune-mediated aggression
Diffuse pyogranulomatous meningochorio-subenendimitis
Vasculitis is a histological hallmark, characteristic prevalence of plasma cells and macrophages
Pyogranulomatous lesions in the eye
What causes louping ill and what transmits it?
What is the inflammatory pattern?
Where is there particular neurotropism?
Flavivirus transmitted by ticks
Inflammatory pattern- non-suppurative polio encephalitis with neuronal necrosis, glial nodules and neuronphagia
Particular neurotropism for Purkinje cells
What kind of virus causes classical swine fever?
What does it grossly cause?
What causes Hepatitis contagiosa canis?
What is its inflammatory pattern?
What causes malignant catarrhal fever?
What lesions does it cause?
ALL ARE EXAMPLES OF VIRAL VASCULITIS
Classical swine fever- pestivirus
disseminated, non-suppurative meningoencephalitis of swine
Hepatitis contagiosa canis- canine adenovirus 1
amophillic inclusion bodies in endothelium, vasculitis and haemorrhage
Malignant catarrhal fever- ovine herpes virus 2, alcephine herpes 1, caprine herpes 2
necrotising and mononuclear vasculitis
What virus causes herpetic encephalomyelitis?
What is the inflammatory pattern?
Equine herpes virus type 1
Petechial or ecchymotic haemorrhages in the white and grey matter of the spine
Inflammatory pattern- vasculitis and thrombosis, suppurative myelitis and haemorrhages
What does suppuration mean?
Recruitment of neutrophils
What generally causes bacterial CNS infections?
Which bacteria is this not true for?
What distribution patterns are characteristic?
Haematogenous spreading, an extension of local inflammations
Listeria not
Both disseminated and focal/multifocal distribution patterns are characteristic
What causes listeriosis?
How does listeria spread in the body?
What is the inflammatory pattern?
Listeria monocytogenes- gram +ve
Retrograde transport along axons and trans-synaptic spreading
Inflammatory pattern: multifocal to coalescing microabscesses
oral cavity to cranial nerves to the brain stem
Small leukomalacic areas
What animals can be affected by mycotic encephalitis?
What can cause encephalitis and what agents?
What is the inflammatory pattern?
All animal species can be effected
Often systemic mycosis or local infection
Aspergillus sp, Mucor
Yeasts- cryptococcus neoformans, candida sp
Inflammatory pattern- necrotising and suppurative- granulomatous or granulomatous meningoencephalitis/myelitis
Necrotic vasculitis and thrombosis common
Love the endothelium
What causes encephalitozoonosis?
What is the inflammatory pattern?
How does it appear histologically?
Encephalitozoon cuniculi, family microsporidia
Obligate intracellular gram-positive parasite
Inflammatory pattern
Disseminated granulomatous encephalitis
Compact epitheloid macrophages
multifocal to massive dissemination throughout the encephalon
What are the intermediate hosts for toxoplasma?
When is the myocardia always involved with toxoplasma?
What is the inflammatory pattern in young and adult animals?
Intermediate hosts are all warm-blooded animals, including humans while definitive hosts are cats
In young or immunocompromised animals the CNS involvement is always associated with severe myocarditis
Inflammatory pattern
Young- non-suppurative polio encephalitis with gliosis
Adult- necrotising and granulomatous encephalitis
What is the suggested pathology of idiopathic inflammatory encephalitis?
What species are affected by granulomatous meningoencephalitis?
How does it appear?
An immune-mediated like reaction or an autoimmune response against specific CNS antigens has been postulated
Adult dogs- no clarified cause
Inflammatory pattern- multifocal to coalescing granulomatous meningoencephalitis
In perivascular cuffs- abundant recruitment of macrophages and lymphocytes
Image shows- granulomatous meningoencephalitis
What are the two types of intervertebral disc herniation?
What does it cause?
Hensen type 1: extrusion of degenerated disc material
Hensen type 2: protrusion without rupture of the annulus fibrosis
Responsible for acute or chronic spinal cord compression with spinal cord degeneration
What is a coup and and a contre-coup?
Describe how acceleration-deceleration injuries occur in the CNS?
Coup- traumatic lesion just beneath the site of impact
Contre-coup- on the opposite side
Acceleration- deceleration injuries:
Caused by sudden stop/deceleration
At the site of impact, cutaneous and cortical haemorrhage can be seen but minimal
At the contralateral haemorrhage site intensity of the lesion is much more pronounced
Describe what a deformation or injury by blow appears like in the CNS?
Caused by a kinetic energy delivered with higher velocity at the impact point
Kinetic energy transforms into deformation of the skull
Large contusion and lacerations extending deeply into the neutroparenchyma at the impact site
Conreolateral haemorrhages are mild or not present
