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Ortho > chapter 7 - peripheral nerve injuries > Flashcards

chapter 7 - peripheral nerve injuries Flashcards

1
Q

4 causes of nerve injuries and examples for each

A
  1. laceration - follow fracture, stab or surgical injury
  2. traction - ie brachial plexus injury, displaced fractures
  3. ischaemia -intraneural injection or compartment syndrome
  4. compression - carpal tunnel syndrome. blind use of artery forceps in a wound may crush a nerve
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2
Q

3 grades of nerve injuries and what they mean

A
  1. neuropraxia = complete motor loss; incomplete sensory loss
  2. axonotmesis = motor and sensory loss complete
  3. neurotmesis = complete division of all nerve elements
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3
Q

which grades present with complete recovery post nerve injury?

A

neuropraxia and axonotmesis

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4
Q

which grade of nerve injury requires surgical repair?

A

neurotmesis

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5
Q

what happens when a nerve is cut?

A
  • nerve dies distally to the site of injury and schwann cells are left behind
  • axon regrowth from injury site to distal stump
  • regenerating axons produce 4-6 sprouts which grow distally towards a motor or sensory end point
  • the first axon to reach the destination becomes the definitive axon and the others die
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6
Q

why do proximal muscles recover better than distal after a nerve injury?

A

proximal muscles receive the first axons

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7
Q

approach to diagnose a peripheral nerve injury

A

est cause of nerve injury
est degree of injury
est site of injury
est type of injury

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8
Q

examination to aid diagnosis of peripheral nerve injury - 6 modalities

A 
1 sensory
motor
reflexes
sudomotor = sweating
vasomotor
trophic
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9
Q

if features of peripheral nerve injury are confusing, what should you suspect

A
  • partial nerve injury

- proximal lesion affecting roots or cords of plexus

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10
Q

what is the aim of the pirmary treatment of upper limb nerve injuries?

A

to prevent oedema and sepsis which cause fibrosis in and around the nerve leading to poor recovery

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11
Q

what is the primary level treatment of upper limb nerve injuries?

A
  • tetanus toxoid 0.5ml
  • antibiotics for hight risk cases
  • GA
  • clean wound with copious lavage - remove foreign material and clots with forceps and wet gauze swabs
  • debride wound but NOT under tourniquet or if patient is shocked
  • secure haemostasis - pressure with tie, clip or fry- bipolar dithermy
  • if nerves are visible - tack the ends together by the epineurium with 5/0 nylon
  • if wihtin a reasonable time since injury- close wound with 5/0 nylon and not silk
  • dress with dry non bulky gauze to allow as much movement as possible
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12
Q

why do you use nylon and not silk sutures on the hand?

A

silk increases local wound inflammation

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13
Q

who should perform a definitive nerve repair

A

only an experienced surgeon - even if that means it will be delayed

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14
Q

what are the 3 required conditions for primary nerve repair?

A

clean wound less than 12 hours old
uncrushed, un torn cleanly incised nerve
minimal gap after trimming - ie no tension

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15
Q

how should you protect the nerve repair post op

A

with a plaster of paris splint

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16
Q

how long should the injury be splinted -

a) major nerves
b) small digital nerves

A

a) 6 weeks

b) 4 weeks

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17
Q

when should you not consider primary repair - 6 situations

A

contaminated wounds more than 12 hours old
avulsions or crushing with torn nerve
multiple severances
large part of nerve mobilised by the injury
large gap
associated avascular necrosis

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18
Q

how do you prevent joint stiffness and swelling post op

A

early physio and OT

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19
Q

how long should you wait beofre you explore a closed nerve lesion and how do you manage the patients during that time

A

6 weeks to 3 months

dynamic splints indicated

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20
Q

what are the dynamic splints for the 3 nerves called

A

knuckle duster splint - median and ulnar palsy

cock up splint - radial palsy

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21
Q

after managing the wound and before surgery what must be done ?

A

actively elevate the limb to prevent oedema and avoid slings if possible

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22
Q

immediately on the day of the injury the patient should start with rehabilitation - what should he do

A

put all joints through full range of motion - every hour to reduce stiffness

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23
Q

after definitive surgery how should the patient be managed?

A

POP splint to protect tendon or nerve repair and allow maximum movement of the other joints
mobilisation by physio and OT

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24
Q

8 factors that influence the prognosis of nerve injury

A 
1 severity of injury
2. persistence of compression by scar tissue 
3 surgical technique 
4 children > young adults > over 40
5 delay before repair
6 pure nerves > mixed nerves
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25
Q

best prognosis with which severity of nerve injury

A

neuropraxia

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26
Q

worst prognosis with which severity of nerve injury

A

neurotemsesis

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27
Q

what causes scar tissue

A

injury
oedema
sepsis
surgical trauma

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28
Q

how is a nerve compressed after arterial injury

A

false aneurysm

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29
Q

if compression of nerve persists what do you do?

A

microsurgical release of scar tissue

surgical decompression is indicated

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30
Q

what is neurolysis

A

surgical decompression

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31
Q

if you delay the repair by x months then it has an effect on recovery

A

6 months

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32
Q

how long can you delay the repair of the nerve - max

A

2 years

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33
Q

what are mixed nerves

A

sensory + motor

34
Q

which type of injuries recover better and why?

A

distal better than proximal

- end plates have not degenerated and the nerve is more likely pure

35
Q

which injuries have the best recovery

A

clean lacerations

36
Q

after a nerve injury what may cause tenderness at a later astage

A

superficial neuromata

37
Q

why would a patient presetn 3-4 weeks after a nerve injury?

A

pain free initially

presents when neuropraxia recovers

38
Q

causes of pain following nerve injury

A 
intra neural injections
bullet injuries
ischaemic injury
intermitten compression - carpal tunnel
traction injuries require spinal rootlets
39
Q

how to manage pain after nerve injury

A
  • analgesia - tramadol or daloxene + codis
  • sedative - largactil 25-50 mg nocte
  • antidepressant - melleril
  • TENS
  • microssurgical neurolysis
40
Q

when will microsurgical neurolysis not work for pain after injury to nerve

A

pain after rootlet avulsions from the spinal cord

41
Q

important sign of brachial plexus injuries

A

senseless limb in deep pressure sensation in the finger tips

42
Q

how do elicit a brachial plexus injury sign?

A

squeeze firmly with finger and thumb on the base of the patients nail and slide it towards the tip

43
Q

if continuity remains post brachial plexus injury- what will the patient feel

A

mild burning in finger tip

44
Q

what does a response to the pressure on the finger tip tell you?

A

the small fibers are present and functioning

45
Q

how long do you wait before exploring the nerve after a brachial plexus injury and what do you do during that time?

A

test small fibers in finger tips at intervals for 6-8 weeks

46
Q

what do you do if deep pressure sense returns after a brachial plexus injury before surgery

A

delay surgery and wait longer 3-5 months

47
Q

how do you determine the level of the lesion in a brachial plexus injury

A

neurological exam

48
Q

which lesions can be seen with CT myelogram

A

avulsion of the roots from the spinal cord - cannot be salvaged with surgery

49
Q

treatment of major nerve injuries? 1 general; 5 specific

A 
- refer for evaluation
external neurolysis
internal neurolysis
nerve grafts
neurotisations
shoulder arthrodesis
50
Q

type of nerve damage with direct sharp injury?

A

neurotmesis

51
Q

clinical of direct shapr injury to nerve

A

sensation and function absent distally

52
Q

treatment of direct sharp injury to nerve

A

repair asap

53
Q

what can neck or shoulder traction cause and when do they occur

A

cervical root avulsions

after motorcycle accidents

54
Q

which nerves are affected in a dislocated shoulder resulting in traction

A

axillary nerve

musculocutaneous nerve or distal plexus

55
Q

what type of nerve injury does traction cause

A

mixed nerve injury

neuropraxia to neurotmesis

56
Q

what limits injury after traction and where

A

perineural and intraneural fibrosis

minimally injured part of the nerve

57
Q

how to treat traction injury

A

splint and watch for 3-6 months

if no progress consider surgery

58
Q

what is a common injury that occurs at birth during delivery and may follow cpd

A

brachical plexus injury

59
Q

in neonates with birth trauma during delivery which nerves roots are commonly affected and what is it called

A

c5 c6 nerve roots - erbs palsy

paralysis of arm and elbow

60
Q

which nerve roots are involved in erbs palsy

A

c5 c6

61
Q

after a brachial plexus injury what should the mum do to the baby and how often

A

abduction and external rotation of the childs shoulder

6 times a day to avoid stiff shoulders

62
Q

after brachial plexus injury at birth which muscles should recover and in what time period

A

deltoid and biceps function

3 months

63
Q

what to do after 3 m if function has not returned

A

consider surgery

64
Q

what surgery is needed for brachical plexus injury in neonata

A

nerve grafts to bridge gap between injured nerve and well nerve
tendon transfers

65
Q

when are tendon transfers indicated post brachial plexus injury in a neonate ie at what age

A

18m till 5 years

66
Q

how does vascular compression by a false aneurysm present

A

progressive paralysis of the limb starting hours, days or a week later

67
Q

which vessels are commonly involved in vascular compression by a false aneurysm

A

subclavian and axillary artery

68
Q

complication of vascular compression by false aneurysm

A

brachial plexus injury

69
Q

how to treat vascular compresion by false aneurysm

A

surgical control of aneurysm

internal neurolysis

70
Q

4 nerve entrapment syndromes of upper limb

A

above shoulder - cervical spondylosis or TOS
median nerve
ulnar nerve
radial nerve

71
Q

entrapment syndromes above the shoudler

A

cervical root foramina in spondylosis

TOS or cervical rib entrament of lower roots of brachial plexus

72
Q

median nerve entrapment syndrome?

A

carpal tunnel

anterior interosseus sundrome - deep branch to thumb and index long flexor passes beneath superficialis arcade

73
Q

ulnar nerve entrapment?

A

cubital tunnel syndrome - elbow injiry

guyons canal at wrist next to pisiform

74
Q

ulnar nerve palsy signs

A

wasting of first web space
clawing of fingers
hyperextension of mpj and flexion at ipj

75
Q

radial nerve entrapment -causes

A

local injury - entrapped at spiral groove of humerus

supinator syndrome around nexk of radius related to local injury or muscle hypertrophy

76
Q

entrapment of nerves in the lower limbs- 5 conditions

A

meralgia paraethetica = lateral cutaneous nerve
lateral popliteal nerve entrapment
tarsal tunnel syndrome
plantar digital nerve neuritis= mortons metatarsalgia
piriformis syndrome

77
Q

how does entrapement of lateral cutaneous nerve of thigh present

A

paraesthesia over lateral thigh

recent weight gain

78
Q

cause of latearl popliteal nerve entrapment

A

anomalous ligaments at neck of fibula

79
Q

mechanism of plantar digital nerve neuritis

A

digital nerve to toes is compressed against intermetatarsal ligament of sole

80
Q

piriformis syndrome compresses which nerve

A

sciatic nerve

Ortho (41 decks)

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