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28 Cards in this Set

  • Front
  • Back
what are the 3 types of peripheral neuropathies?
- axonal

- demyelinating

- wallerian degeneration
what is the difference between the epi & perineurium?
- perineurium surrounds each fasicle (whole nerve)

- epineurium binds all the fascicles in the nerve
which axonal transport is towards & away from cell body? does it require energy?
- anterograde: towards synapse

- retrograde: towards cell body

- energy dependent
what happens in muscle if you effect anterograde transport?
- muscle can atrophy because it is involved in maintaining muscle
what do vincristine & vinblastine do?
- 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
which protein is involved in rapid axonal transport? what does it carry?
- kinesin (ATP dependent)

- carries synaptic vesicles & membrane bound proteins like plasma membrane proteins
what does slow axonal transport carry?
- soluble enzymes and tubulin used in making microtubules

- determines rate of recovery from nerve injury as it is needed to transport structural components
which type of axonal transport determines rate of recovery from nerve injury?
- slow axonal transport
what is chromatolysis? who incudces this?
- nerve body swells, nissl substance dissolves (seen in beginning of regeneration & apoptosis)

- carried by retrograde transport
which motor protein is important for retrograde transport?
- dynein
what is wallerian degeneration?
- dying forward

- degneration from point of axonal injury peripherally

- Nerve dies forward, get muscle atrophy, chromatolysis
what does the degeneration pattern look like in axonal degeneration?
- metabolic derangement, from most distal part --> proximal part of axon

- Nerve dies forward, get muscle atrophy, chromatolysis
what happens in segmental demyelination?
- axon is in tact, no chromatolysis, myelin is damaged & don't get conduction through this section

- muscle does not atrophy, cell body is ok
if injury is distal to DRG what types of neurons are injured?
- sensory & motor
what if injury is proximal to DRG?
- sensory axon will be normal
what does proximal vs distal weakness indicate?
- distal indicates axonal

- proximal indicates demyelinating or myopathic pattern
what is the timeline for axonal neuropathy? distribution? reflexes? muscle tone?
- slow & chronic

- stocking-glove distribution

- loss of reflexes distally

- muscle wasting distally

- decreased CMAPS (motor), absent SNAP
what happens to CMAP in axonal neuropathy?
- 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)
what is Guillian - Barre syndrome?
- primarily motor, can be sensory, myelin disruption

- rapidly progessive (peaks in 2 weeks)

- areflexia & ataxia because demyelination of the sensory component too
do muscles waste in guillian-barre syndrome?
- no because axonal transport & axon is ok, but myelin is not functioning so nerve is not functioning
what happens to CMAP in segmental demyelination?
- loss of CMAP beyond the myelin
what kinds of demyelinating polyneuropathies are there?
- autoimmune: guillian-barre, CIDP, antibodies

- genetic: charcot-marie tooth type I, metachromatic leukodystrophy
what are onion bulbs?
- when you have chronic demyelinating disease where you get demyelination and remyelination looks like onion bulb
what happens in ischemic mononeuritis multiplex?
- can be seen in polyarteritis nodosa

- nerve infarcts b/c blood flow to nerve is compromised in vasculitis
what kinds of different focal neuropathies are possible?
- compressive

- ischemic: diabetic or vasculitic. Fascicular injury

- infiltrative: neoplastic or granulomatous

- autoimmune: brachial plexopathy
what happens in wallerian degneration?
- 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
what is the difference between axonotmesis vs neurotmesis with wallerian degneration?
- if schwann cells are not disrupted will regenerate - axonotmesis

- if schwann cells disrupted reinnervation cannot occur - neurotmesis
what are the 3 classes of traumatic nerve injury?
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