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28 Cards in this Set
- Front
- Back
what are the 3 types of peripheral neuropathies?
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- axonal
- demyelinating - wallerian degeneration |
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what is the difference between the epi & perineurium?
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- perineurium surrounds each fasicle (whole nerve)
- epineurium binds all the fascicles in the nerve |
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which axonal transport is towards & away from cell body? does it require energy?
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- anterograde: towards synapse
- retrograde: towards cell body - energy dependent |
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what happens in muscle if you effect anterograde transport?
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- muscle can atrophy because it is involved in maintaining muscle
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what do vincristine & vinblastine do?
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- arrest mitosis in rapidly developing cells to disrupt cancer cells
- because it binds to tubulin it damages nerves as well & can cause denervated muscle atrophy |
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which protein is involved in rapid axonal transport? what does it carry?
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- kinesin (ATP dependent)
- carries synaptic vesicles & membrane bound proteins like plasma membrane proteins |
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what does slow axonal transport carry?
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- soluble enzymes and tubulin used in making microtubules
- determines rate of recovery from nerve injury as it is needed to transport structural components |
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which type of axonal transport determines rate of recovery from nerve injury?
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- slow axonal transport
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what is chromatolysis? who incudces this?
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- nerve body swells, nissl substance dissolves (seen in beginning of regeneration & apoptosis)
- carried by retrograde transport |
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which motor protein is important for retrograde transport?
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- dynein
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what is wallerian degeneration?
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- dying forward
- degneration from point of axonal injury peripherally - Nerve dies forward, get muscle atrophy, chromatolysis |
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what does the degeneration pattern look like in axonal degeneration?
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- metabolic derangement, from most distal part --> proximal part of axon
- Nerve dies forward, get muscle atrophy, chromatolysis |
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what happens in segmental demyelination?
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- axon is in tact, no chromatolysis, myelin is damaged & don't get conduction through this section
- muscle does not atrophy, cell body is ok |
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if injury is distal to DRG what types of neurons are injured?
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- sensory & motor
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what if injury is proximal to DRG?
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- sensory axon will be normal
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what does proximal vs distal weakness indicate?
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- distal indicates axonal
- proximal indicates demyelinating or myopathic pattern |
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what is the timeline for axonal neuropathy? distribution? reflexes? muscle tone?
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- slow & chronic
- stocking-glove distribution - loss of reflexes distally - muscle wasting distally - decreased CMAPS (motor), absent SNAP |
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what happens to CMAP in axonal neuropathy?
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- lower amplitude CMAP telling you muscle is atrophied
- with proximal stimulation velocity is about same & amplitude about same (because there are some axons still & some not functioning) |
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what is Guillian - Barre syndrome?
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- primarily motor, can be sensory, myelin disruption
- rapidly progessive (peaks in 2 weeks) - areflexia & ataxia because demyelination of the sensory component too |
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do muscles waste in guillian-barre syndrome?
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- no because axonal transport & axon is ok, but myelin is not functioning so nerve is not functioning
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what happens to CMAP in segmental demyelination?
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- loss of CMAP beyond the myelin
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what kinds of demyelinating polyneuropathies are there?
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- autoimmune: guillian-barre, CIDP, antibodies
- genetic: charcot-marie tooth type I, metachromatic leukodystrophy |
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what are onion bulbs?
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- when you have chronic demyelinating disease where you get demyelination and remyelination looks like onion bulb
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what happens in ischemic mononeuritis multiplex?
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- can be seen in polyarteritis nodosa
- nerve infarcts b/c blood flow to nerve is compromised in vasculitis |
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what kinds of different focal neuropathies are possible?
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- compressive
- ischemic: diabetic or vasculitic. Fascicular injury - infiltrative: neoplastic or granulomatous - autoimmune: brachial plexopathy |
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what happens in wallerian degneration?
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- distruption of anterograde transport means organelles cannot be transmitted to distal axons & cannot renew membrane
- retrograde transport tells cell to increase metabolic acitvity & produce GFs for axonal regeneration |
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what is the difference between axonotmesis vs neurotmesis with wallerian degneration?
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- if schwann cells are not disrupted will regenerate - axonotmesis
- if schwann cells disrupted reinnervation cannot occur - neurotmesis |
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what are the 3 classes of traumatic nerve injury?
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Class I neurapraxia: stretch injury or compressive, demyelinating, may recover in weeks to months
Class 2 axonotmesis: axon destroyed but nerve sheath intact, slow process Class 3 neurotmesis: sheath is transected or destroyed will not regenerate |