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Year 3: Block 1: MSK system > Peripheral nerve injuries > Flashcards

Peripheral nerve injuries Flashcards

1
Q

3 features of the motor unit (efferent)

A

anterior horn cell, (located in the gray matter of the spinal cord)
motor axon,
muscle fibres (neuromuscular junctions)

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2
Q

Sensory unit (2)

A

cell bodies in posterior root ganglia

I.e. lie outside the spinal cord

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3
Q

Nerve fibres join to form

A

anterior (ventral) motor roots

posterior (dorsal) sensory roo

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4
Q

What forms a spinal nerve

A

Anterior and posterior roots

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5
Q

how do spinal nerves exit the vertebral column

A

intervertebral foramen.

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6
Q

The part of a spinal nerve distal to the nerve roots is?

A

Peripheral

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7
Q

How are peripheral nerves structured

A

highly organised structure comprised of nerve fibres, blood vessels and connective tissue

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8
Q

The 3 parts in the structure of peripheral nerves

A

AXONS (long processes of neurones) are coated with endoneurium and grouped into

FASCICLES (nerve bundles ) covered with perineurium; these are grouped to form the

NERVE which is covered with epineurium

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9
Q

Neurones are surrounded by ?

A

schwann cells

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10
Q

Peripheral nerve injuries main 2 types

Trauma - types

A

compression - (nerve palsies)

trauma - direct (blow, laceration) or indirect (avulsion, traction

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11
Q

3 types of injuries

A

neurapraxia
axonotmesis
neurotmesis

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12
Q

Compression - ENTRAPMENT Classical conditions (3) - what nerves are affected

A 
Carpal tunnel syndrome
Median nerve at wrist
Sciatica
Spinal root by intervertebral disc
Morton’s neuroma 
(digital nerve in 2nd or 3rd web space of forefoot)
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13
Q

NEURAPRAXIA - describe this (4)

what do you get?
what ultimately then can’t you get?

A

nerve in continuity - all way down -
stretched (8% will damage microcirculation) or bruised
reversible conduction block - local ischaemia and demyelination
prognosis good (weeks or months)

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14
Q

AXONOTMESIS - - what is intact ?

features?
prognosis?

(3)

A

endoneurium intact (tube in continuity), but disruption of axons; (nerve disappears) more severe injury

Stretched - direct blow/crushed

sensory recovery often better than motor - often not normal but enough to recognise pain, hot & cold, sharp & blunt)

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15
Q

What degeneration follows AXONOTMESIS

A

Wallerian degeneration

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16
Q

What can peripheral nerves do

A

Regenerate

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17
Q

What is the start of the peripheral nerve

A

spinal nerve

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18
Q

NEUROTMESIS - what is this

A

complete nerve division

laceration or avulsion

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19
Q

NEUROTMESIS - there is no recovery unless…

A

repaired (by direct suturing or grafting)

20
Q

In NEUROTMESIS what tubes are disrupted?

A

endoneural tubes
high chance of “miswiring” during regeneration
prognosis poor

21
Q

What grading may be used?

A

sunderland

22
Q

Nerve injuries - closed

what are they associated with? (2)

A

nerve injuries in continuity
neuropraxis
axonotmesis,

23
Q

in what nerve injury is spontaneous recovery possible

A

closed

24
Q

when is surgery indicated for closed nerve damage

A

3 months
if no recovery is identified
Clinical
Electromyography

25
Q

Axonal growth rate for closed nerve injuries

A

1–3 mm/day

26
Q

give examples of closed nerve injures

A

brachial plexus injuries

Radial Nerve humeral fracture

27
Q

Open fractures or open injuries are related to

How is it treated?

A

nerve division

neurotmetic injuries
E.g. knives /glass

early surgery

28
Q

In open injury - what part or nerve undergoes Wallerian degeneration

A

Distal portion

29
Q

Clinical features- sensory (1-2)

A

dysaethesiae (disordered sensation)

anaesthetic (numb), hypo- & hyper-aesthetic, paraesthetic (pins & needles)

30
Q

Motor clinical features (2)

A

paresis (weakness) or paralysis ± wasting
dry skin
loss of tactile adherence since sudomotor nerve fibres not stimulating sweat glands in skin

31
Q

Peripheral nerves carry

A

para and sympa

sweat glands not stimulated in the skin

32
Q

No peripheral nerves will mean that reflexes are

A

diminished or absent

33
Q

healing of nerve injuries

A

very slow
death of axons - distal to site of injury

Wallerian degeneration
Then degradation myelin sheath

34
Q

proximal axonal budding occurs after? (start of growth)

A

4 days

35
Q

regeneration proceeds at rate of about ?

A

1 mm/day (or 1 inch/month) - poss. 3-5 mm/day in children

36
Q

What is the first modality to return?

A

PAIN

37
Q

Prognosis depends on

A

pure of mixed nerve

Pure - tend to recover better

mixed - variable recovery

HOW DISTAL THE lesion is

38
Q

Best Nerve position for recovery

A

distal

39
Q

What signs can monitor recovery

A

Tinel

tap over site of nerve and paraesthesia will be felt as far distally as regeneration has progressed)

40
Q

Nerve monitored by what study

A

electrophysiological Nerve Conduction Studies

41
Q

Tinel’s can be used for

A

carpel tunnels syndrome

compression

42
Q

nerve repair - direct

A 
Laceration
No loss nerve tissue
Microscope/Loupes
Bundle repair
Growth factors
43
Q

Nerve grafting is used when (3)

A
  • Nerve loss
    Late repair
    (retraction)
    Sural nerve
44
Q

The rule of three - timings for surgery

A

Immediate surgery within 3 days for clean and sharp injuries

Early surgery within 3 weeks for blunt/contusion injuries

Delayed surgery, performed 3 months after injury, for closed injuries.

45
Q

Peripheral/ central nerve injuries may result in loss of ?

A

motor function, sensory function, or both

46
Q

how to tell difference clinical between Peripheral or Central

A

LMN - peripheral - whole nerve transected

umm - PERIPHERAL NERVE still intact

47
Q

In UMN - tone and reflexes are

A

INCREASED

Year 3: Block 1: MSK system (22 decks)

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