3.14 Ch. 12.2 Flashcards Preview

7303 Neuroanatomy > 3.14 Ch. 12.2 > Flashcards

Flashcards in 3.14 Ch. 12.2 Deck (31):
1

types of peripheral neuropathies

- mononeuropathy
- multiple mononeuropathy
- polyneuropathy

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mononeuropathy

Involves a single nerve and is considered a focal dysfunction

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multiple mononeuropathy

- Involves several nerves
- is multifocal (i.e., asymmetrically involves individual nerves).

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polyneuropathy

- Involves many nerves
- is a generalized disorder that typically has a distal and symmetrical presentation.

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3 categories of traumatic injuries

- traumatic myelinopathy
- traumatic axonopathy
- severance

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traumatic myelinopathy refers to the loss of

- myelin
- limited to the site of injury

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peripheral myelinopathies interfere with

function of large-diameter axons

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What causes traumatic myelinopathy?

focal compression of a peripheral nerve

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What can cause focal compression?

repeated mechanical stimuli

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Where does traumatic axonopathy occur?

distal to the lesion

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What does traumatic axonopathy disrupt?

- axons
- Wallerian degeneration

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What does traumatic axonopathy affect?

- all sizes of axons
- reflexes
- somatosensation
- motor functions

**reduced or absent

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traumatic axonopathy and regenerating axons

Regenerating axons are able to reinnervate appropriate targets because myelin and connective tissues remain intact.

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When does severance occur?

- when nerves are physically divided by excessive stretching or laceration

- axons and connective tissue are completely interrupted

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What does severance result in immediately?

- loss of sensation
- muscle paralysis in area supplied

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What happens if proximal and distal nerve stumps are apposed and scarring does not interfere?

some sprouts enter the distal stump and are guided to their target tissue in the periphery

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What does multiple mononeuropathy involve?

two or more nerves in different parts of the body

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What may cause multiple mononeuropathy?

vasculitis

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What should be done if vasculitis is suspected?

an urgent referral should be made for an electrodiagnostic evaluation

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nerves affected with multiple mononeuropathy

What does this produce?

- individual nerves are affected
- produces a random, asymmetrical presentation of signs

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hallmark signs of polyneuropathy

- symmetrical involvement of sensory, motor, and autonomic fibers
- often progresses from distal to proximal

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Polyneuropathies are NOT the result of

- trauma
- ischemia

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causes of polyneuropathies (Categories)

- toxic
- metabolic
- autoimmune

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Most common causes of polyneuropathies

- diabetes
- nutritional deficiencies 2˚ to alcoholism
- autoimmune diseases

(also some therapeutic drugs, industrial and agricultural toxins, and nutritional disorders)

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polyneuropathy in Guillain-Barré has more severe effects on (motor/sensory) than (motor/sensory) system

motor
sensory

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Guillain-Barré: proximal

paresis may be worse

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Guillain-Barré: onset

- rapid with progressive paralysis
- urgent dx and tx required to prevent respiratory failure

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Guillain-Barré: patients requiring a ventilator

1/3 of pts will need a ventilator

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most common inherited form of polyneuropathy

Charcot-Marie-Tooth disease

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Charcot-Marie-Tooth disease: onset

typically occurs in adolescence or in young adults but varies with type

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Charcot-Marie-Tooth disease: presentation

paresis of muscles distal to knee with
- foot drop
- steppage gait
- frequent tripping
- muscle atrophy

*in progression, atrophy and paresis affect hands*