Peripheral nerve injuries

Question 1

3 features of the motor unit (efferent)

Answer 1

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

Question 2

Sensory unit (2)

Answer 2

cell bodies in posterior root ganglia

I.e. lie outside the spinal cord

Question 3

Nerve fibres join to form

Answer 3

anterior (ventral) motor roots

posterior (dorsal) sensory roo

Question 4

What forms a spinal nerve

Answer 4

Anterior and posterior roots

Question 5

how do spinal nerves exit the vertebral column

Answer 5

intervertebral foramen.

Question 6

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

Answer 6

Peripheral

Question 7

How are peripheral nerves structured

Answer 7

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

Question 8

The 3 parts in the structure of peripheral nerves

Answer 8

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

Question 9

Neurones are surrounded by ?

Answer 9

schwann cells

Question 10

Peripheral nerve injuries main 2 types

Trauma - types

Answer 10

compression - (nerve palsies)

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

Question 11

3 types of injuries

Answer 11

neurapraxia
axonotmesis
neurotmesis

Question 12

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

Answer 12

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)

Question 13

NEURAPRAXIA - describe this (4)

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

Answer 13

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)

Question 14

AXONOTMESIS - - what is intact ?

features?
prognosis?

(3)

Answer 14

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)

Question 15

What degeneration follows AXONOTMESIS

Answer 15

Wallerian degeneration

Question 16

What can peripheral nerves do

Answer 16

Regenerate

Question 17

What is the start of the peripheral nerve

Answer 17

spinal nerve

Question 18

NEUROTMESIS - what is this

Answer 18

complete nerve division

laceration or avulsion

Question 19

NEUROTMESIS - there is no recovery unless…

Answer 19

repaired (by direct suturing or grafting)

Question 20

In NEUROTMESIS what tubes are disrupted?

Answer 20

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

Question 21

What grading may be used?

Answer 21

sunderland

Question 22

Nerve injuries - closed

what are they associated with? (2)

Answer 22

nerve injuries in continuity
neuropraxis
axonotmesis,

Question 23

in what nerve injury is spontaneous recovery possible

Answer 23

closed

Question 24

when is surgery indicated for closed nerve damage

Answer 24

3 months
if no recovery is identified
Clinical
Electromyography

Question 25

Axonal growth rate for closed nerve injuries

Answer 25

1–3 mm/day

Question 26

give examples of closed nerve injures

Answer 26

brachial plexus injuries | Radial Nerve humeral fracture

Question 27

Open fractures or open injuries are related to How is it treated?

Answer 27

nerve division neurotmetic injuries E.g. knives /glass early surgery

Question 28

In open injury - what part or nerve undergoes Wallerian degeneration

Answer 28

Distal portion

Question 29

Clinical features- sensory (1-2)

Answer 29

dysaethesiae (disordered sensation) | anaesthetic (numb), hypo- & hyper-aesthetic, paraesthetic (pins & needles)

Question 30

Motor clinical features (2)

Answer 30

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

Question 31

Peripheral nerves carry

Answer 31

para and sympa | sweat glands not stimulated in the skin

Question 32

No peripheral nerves will mean that reflexes are

Answer 32

diminished or absent

Question 33

healing of nerve injuries

Answer 33

very slow death of axons - distal to site of injury Wallerian degeneration Then degradation myelin sheath

Question 34

proximal axonal budding occurs after? (start of growth)

Answer 34

4 days

Question 35

regeneration proceeds at rate of about ?

Answer 35

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

Question 36

What is the first modality to return?

Answer 36

PAIN

Question 37

Prognosis depends on

Answer 37

pure of mixed nerve Pure - tend to recover better mixed - variable recovery HOW DISTAL THE lesion is

Question 38

Best Nerve position for recovery

Answer 38

distal

Question 39

What signs can monitor recovery

Answer 39

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

Question 40

Nerve monitored by what study

Answer 40

electrophysiological Nerve Conduction Studies

Question 41

Tinel's can be used for

Answer 41

carpel tunnels syndrome | compression

Question 42

nerve repair - direct

Answer 42

``` Laceration No loss nerve tissue Microscope/Loupes Bundle repair Growth factors ```

Question 43

Nerve grafting is used when (3)

Answer 43

- Nerve loss Late repair (retraction) Sural nerve

Question 44

The rule of three - timings for surgery

Answer 44

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.

Question 45

Peripheral/ central nerve injuries may result in loss of ?

Answer 45

motor function, sensory function, or both

Question 46

how to tell difference clinical between Peripheral or Central

Answer 46

LMN - peripheral - whole nerve transected umm - PERIPHERAL NERVE still intact

Question 47

In UMN - tone and reflexes are

Answer 47

INCREASED