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MSK > Musculoskeletal Growth/Injury and Repair - Nerve > Flashcards

Musculoskeletal Growth/Injury and Repair - Nerve Flashcards

1
Q

What is an axon?

A

Long processes of neurones coated with endoneurium

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2
Q

What are fascicles?

A

Nerve bundles (groups of axons) covered with perineurium

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3
Q

What are nerves?

A

Groups of fascicles covered in epineurium

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4
Q

What are peripheral neurones surrounded by?

A

Schwann cells

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5
Q

What are the fiber types and functions?

A

SAVED AS FIBER TYPES AND FUNCTIONS

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6
Q

How can nerves be injured?

A
  • Compression

* Trauma - direct (blow, laceration) or indirect (avulsion, traction)

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7
Q

What can nerve compression also be known as?

A

Nerve entrapment

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8
Q

What are the classical nerve compression conditions (3)?

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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9
Q

What are the 3 types of trauma nerve injury?

A

•Neurapraxia
•Axonotmesis
•Neurotmesis
SAVED AS NERVE TRAUMA

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10
Q

What is neurapraxia?

A
  • Nerve in continuity
  • Stretched (8% will damage microcirculation) or bruised
  • Reversible conduction block - local ischaemia and demyelination
  • Prognosis good (weeks or months)
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11
Q

What is axonotmesis?

A
  • Endoneurium intact (tube in continuity), but disruption of axons; more severe injury
  • Stretched ++ (15% elongation disrupts axons) or crushed or direct blow
  • Wallerian degeneration follows
  • Prognosis fair (sensory recovery often better than motor - often not normal but enough to recognise pain, hot & cold, sharp & blunt)
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12
Q

What is neurotmesis?

A
  • Complete nerve division
  • Laceration or avulsion
  • No recovery unless repaired (by direct suturing or grafting)
  • Endoneural tubes disrupted so high chance of “miswiring” during regeneration
  • Prognosis poor
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13
Q

What are the 2 classifications of nerve injury?

A

Open or closed

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14
Q

Describe closed nerve injuries?

A

•Associated with nerve injuries in continuity - neuropraxis
axonotmesis,
•Spontaneous recovery is possible
•Surgery indicated after 3 months
•If no recovery is identified - clinical, electromyography
•Axonal growth rate (1–3 mm/day)
•Examples - Typically stretching of nerve
e.g. brachial plexus injuries
or radial nerve humeral fracture

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15
Q

Describe open nerve injuries?

A

•Frequently related to nerve division - neurotmetic injuries
E.g. knives /glass
•Treated with early surgery
•Distal portion of the nerve undergoes Wallerian degeneration - occurs up 2 to 3 weeks after the injury

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16
Q

What are the sensory features of peripheral nerve injury?

A
  • Dysthaesiae (disordered sensation) e.g.
  • Anaesthestic - numb
  • Hypo/hyper-aesthetic
  • Paraesthetic - pins and needles
17
Q

What are the motor features of peripheral nerve injury?

A
  • Paresis (weakness) or paralysis ± wasting

* Dry skin - loss of tactile adherence since sudomotor nerve fibres not stimulating sweat glands in skin

18
Q

What are the reflex features of peripheral nerve injury?

A

•Diminished or absent

19
Q

How well do nerve injuries heal?

A

•Slow
•Starts with initial death of axons distal to site of injury - Wallerian degeneration
and then degradation myelin sheath
•Proximal axonal budding occurs after about 4 days
•Regeneration proceeds at rate of about 1 mm/day (or 1 inch/month) - poss. 3-5 mm/day in children

20
Q

What is the first modality to return after nerve injury?

A

Pain

21
Q

What factors affect the prognosis for nerve recover (2)?

A
  • Whether nerve is pure of mixed

* How distal the lesion is - proximal worse

22
Q

What sign can monitor nerve hearing?

A

Tinel’s - tap over nerve to see how distally nerve regeneration has progressed

23
Q

What are electrophysiological nerve conduction studies?

A

A way of assessing injury and recovery of nerve injury

24
Q

How are clean and sharp nerve injuries treated?

A

Immediate surgery within 3 days

25
Q

How are blunt/contusion nerve injuries treated?

A

Early surgery within 3 weeks

26
Q

How are closed nerve injuries treated?

A

Delayed surgery, performed 3 months after injury

27
Q

How do you tell if a nerve injury is peripheral or central?

A

SAVED UNDER PERIPHERAL OR CENTRAL

28
Q

How can nerves be repaired (2)?

A
  • Direct repair

* Nerve grafting

29
Q

How are nerves directly repaired?

A
  • When laceration with 2 nerve endings close together with no loss of nerve tissue
  • Done using microscope or loupes
  • Nerve bundles repaired
  • Growth factors not in routine use
30
Q

How are nerves repaired using grafting?

A
  • Where there is loss of nerve or retraction of nerve (cannot be pulled together in late repair)
  • Sural nerve used to provide “tubes” - not a particularly useful nerve
31
Q

What does Babinski’s sign indicate? PLANTAR REFLEX

A

UPM damage

MSK (28 decks)

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