Neuropathy Flashcards

1
Q

What are the layers of the meninges from deep to superficial?

A
  • Pia
    • Thin
  • Arachnoid
    • Spider-like
    • Thin
  • Dura
    • Thick
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2
Q

Where are the astrocytes found and what is their function?

A
  • Found in the central nervous system
  • Functions
    • Structural- create blood-brain barrier and supportive framework for neurons
    • Insulates synapses
    • Mildly phagocytic
    • Metabolic functions
    • Monitor and regulate interstitial fluid surrounding neurons
    • Transmit information to each other
    • Stimulate the formation of scar tissue
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3
Q

Where are the microglia found and what is their function?

A
  • Phagocytes of the CNS- similar to macrophages
  • Brain will recruit if infection present
  • Smallest of the glial cells
  • Cigar-shaped when reactive
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4
Q

Where are the oligodendrocytes found? What are their functions?

A
  • Produce myelin in the CNS
  • Surround few axonal processes
  • Injury will cause demyelination
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5
Q

Where are the ependymal cells found? What is their function?

A
  • Found in the CNS
  • Cuboidal cells
  • Line cavities and ventricals of CNS
  • CSF production
  • Barrier functions
  • Give rise to epithelial layer that surrounds the choroid plexu
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6
Q

Where are the Schwann cells found and what is their function?

A
  • Myelinate axons in the PNS
  • Surround all axons of neurons in the PNS
  • One schwann cell can myelinate many axons
  • Wraps around a cell and squeeze out the cytoplasm so that all that is left is the myelin sheath
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7
Q

Where are the satelite cells found and what is their function?

A
  • Support cells in the PNS, mainly in ganglia
  • PNS equivalent of astrocytes
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8
Q

Why are neurons vulnerable to injury?

A
  • They have a high metabolic rate
  • They have little energy storage
  • They have to take care of their axon
    • The axon has no nissl substance
      • Cannot make protein
      • Cannot dispose of own waste
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9
Q

What is being pictured here? In what condition will this be seen?

A
  • Chromatolysis of neuronal cells
  • Cells get bigger
  • Adaptive response to injury
  • Does not usually resolve
  • Seen in equine grass sickness
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10
Q

What is being depicted here? What can cause this condition?

A
  • Neuronal wallarian degeneration
  • Cells fall apart
  • Breakdown of a nerve fibre distal to the point of injury (downstream to where the insult took place)
  • Can occur with compression or stretching injury
  • Creates axonal debris which has to be cleared by the myelo-macrophages to create a platform for healing
  • Some regeneration can occur and may form a neuroma (mass of neurons- can be painful)
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11
Q

What is being depicted here? What may cause this condition?

A
  • Neuronal vacuolation
  • Cells become vacuolated
  • Rare form of injury
  • Common artefact in histology
  • Seen with
    • Transmissible spongiform encephalopathies
    • Lysosomal storage diseases
    • Early cell injury
    • Some toxins
  • Order of susceptibility (from most to least susceptible)
    • Nerons, oligodendrocytes, astrocytes, microglia, blood vessels
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12
Q

What is being depicted here? What causes this disorder?

A
  • Acute neuronal necrosis
  • Usually a result of ischaema
  • Non-ischaemic causes of neuronal necrosis
    • Hypoxia
    • Hypoglycaemia
    • Nutritional deficiency
    • Toxins
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13
Q

What are some causes of laminar cortical necrosis?

A
  • Salt poisoning
  • Water deprivation
  • Lead and mercury toxicity
  • Polioencephalomalacia in ruminants (cerebrocortical necrosis (CCN))Pathology unclear but is thought to be a thiamine deficiency or sulfide toxicity
  • Thiamine is required for glucose metabolism
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14
Q

Describe neural cytoxic oedema.

A
  • ATP deficit and failure of sodium pump where sodium and water build up within the cell (similar to hydropic degeneration)
  • Intracellular
  • Can occur as a result of hypoxia, ischaemia, and toxins
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15
Q

Describe the types of demyelination.

A
  • Primary
    • Myelin forms normally and then is selectively destroyed
    • Caused by: toxicity, circulatory oedema, immune mediated, infectious cases, idiopathic, and hereditary, impaired maintenance, nutritional (copper, vitamin B12), toxins (cyanide)
  • Secondary
    • Loss of myelin following axonal damage (Wallerian degeneration, for example)
    • The myelin is not able to be formed properly
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16
Q

What is Fibrocartilaginous embolic myelopathy (FCEM)?

A
  • Results from the blockage of blood vessels
  • Key features
    • Large breed dogs commonly affected
    • Acute onset
    • Non-progressive course
    • Non-painful dramatic asymmetric paresis or paralysis without involvement of the head (animals are quite bright otherwise)
    • 60% of cases have history of trauma
  • Marrow Embolism following fracture
17
Q

Describe different characteristics of viral entry into the central nervous system.

A
  • Neurotropic
    • Are able to bypass into the nervous system
    • Viruses which can overcome innate immunity of brain- Rabies (Rhambdovirus), for examplee
    • Lesions are microscopic
  • Endothelioptropic
    • Endothelial cell damage leads to vascular injury and secondary parenchymal necrosis and haemorrhage
  • Pantropic
    • affecting various tissues without showing special affinity for one of them
    • Infectious Bovine Rhinotracheitis (IBR), for example
    • Virus can be latent in nerve ganglia
18
Q

Desribe the sequelae, symptoms, and forms of listeriosis.

A
  • Sequelae
    • Infection of oral mucosa caused by consuming basic silage
    • Infections of trigeminal nerve
    • Infection of trigeminal ganglion in brain
  • Forms
    • CNS
    • Abortion
    • Sepsis
  • Symptoms
    • Circling
    • Facial nerve paralysis
    • Drooling
    • Pharyngeal paralysis
    • Recumbency, paddling, death
19
Q

What is a contusion?

A

A region of injured tissue or skin in which blood capillaries have been ruptured

20
Q

Describe the different types of intervertebral Disk Disease (IVDD).

A
  • Chondrodystrophic
    • Nucleus pulposus replaced by chondroid tissue
    • Degeneration of annulus fibrosis is secondary
    • Common in young dogs
  • Non-condrodystrophic
    • Degeneration begins in annulus fibrosis
    • Nucleus pulposus undergoes fibrsosis
    • Common in middle-aged dogs
    • Age-related and not breed dependent
21
Q

What is cervical vertebral stenotic myelopathy?

A
  • “Wobbler” horse syndrome
  • Due to malformation and malalignment of the cervical vertebrae
  • Found in fast-growing and young horses
  • Can lead to cord compression and hindlimb ataxia
22
Q

What is hydrocephalus? Describe the types of hydrocephalus.

A
  • Increased amount of fluid within the cranial cavity as a whole
  • Internal (Common)
    • Within ventricles
  • Congenital
    • Obstruction not found
    • Common in brachycephalic dogs- mesencephalic aqueduct may be stenotic
    • Sporadic in cattle
  • Acquired form
    • Causes: obstruction due to inflammation or space-occupying lesion (SOL) compression
  • External
    • Within arachnoid space
  • Communicating
    • Within both locations
  • Hyrocephalus ex vacuo
    • Ventricles dilate to replace lost tissue
    • Generally caused by blockage of flow through the ducts
23
Q

What are the different types of cerebellar hypoplasia?

A
  • Inherited
  • Acquired
    • Usually due to environmental teratogens which attack germinal cells in external granular layer of cerebellum (source of neurons)
    • Can be caused by parvo and pestiviruses
    • Feline panleukopaenia, canine parvovirus, schmallenberg virus, for example
24
Q

What is cerebellar abiotrophy?

A

Premature degeneration of nervous tissue elements after they have formed

25
Q

Describe the potential neuropathy of guttural pouch mycosis.

A

Can spread to the recurrent laryngeal nerve and lead to vocal cord hemiplegia (paralysis of one side)

26
Q

Describe neural lysosomal storage diseases.

A
  • A group of rare diseases, mostly inherited, which often affect the CNS
  • Lack of enzymes in lysosomes leads to a build-up of waste substrate in the cell
  • Globoid cell leukodystrophy (Krabbe’s disease)
    • Myelin is not broken down properly to galactocerebroside and psychosine