Nerve injury

Question 1

What are the types of nerve injuries?

Answer 1

STRETCHING

• 8% elongation –> nerve microcirculation diminished
• 15% elongation –> axon disruption

COMPRESSION/CRUSH

• deformity of fibers
• local ischemia

LACERATION
- sharp transections have better prognosis than crush

Question 2

What is Seddon’s classification?

Answer 2

Neuropraxia
Axonotmesis
Neurotmesis

Question 3

What is neurapraxia?

Answer 3

• caused by local ischemia (mechanical pressure)
• axon & endoneurium remain intact
• nerve conduction velocity slow or blocked
• no fibrillation potential
• spontaneous recovery

Question 4

What is axonotmesis?

Answer 4

• incomplete nerve injury more severe than neuropraxia
• axon & myelin sheath disruption
• focal conduction block with Wallerian
• variable degree of c.t disruption
• fibrillations & positive sharp waves on EMG
• unpredictable recovery

Question 5

What is neurotmesis?

Answer 5

• complete nerve division with disruption of endoneurium & all c.t
• focal conduction block with Wallerian degeneration
• fibrillations & positive sharp waves on ECG
• no recovery without surgical repair

Question 6

What is seen in crutch palsy & saturday night palsy?

Answer 6

neurapraxia

Question 7

What is seen in closed fractures & dislocations?

Answer 7

axonotmesis

Question 8

Which nerve injury could lead to formation of neuroma on proximal nerve?

Answer 8

neurotmesis

leads to chronic pain

Question 9

an anterior shoulder dislocation could injure which nerve?

Answer 9

axillary nerve

Question 10

What injuries could cause a radial nerve injury?

Answer 10

• distal humeral shaft fracture (Holstein-Lewis)
• Saturday night palsy
• Extension-type supracondylar humerus fracture

Question 11

Extension-type supracondylar humerus fracture could injure which nerve?

Answer 11

• anterior interosseous nerve

- radial nerve

Question 12

improper position on table, distal humerus ORIF, & flexion-type supracondylar humerus fracture cause what nerve injury?

Answer 12

ulnar nerve

Question 13

posterior hip dislocation could injure which nerve?

Answer 13

sciatic nerve

Question 14

total knee arthroplasty could injure which nerve?

Answer 14

common peroneal nerve

Question 15

percutaneous plating of tibial fractures could injure which nerve?

Answer 15

superficial peroneal nerve

Question 16

What investigations are used to assess nerve injury?

Answer 16

ELECTROMYOGRAPHY

• assess function at neuromuscular level
• compressive neuropathy’s characteristic findings:
  - denervation of muscle
  - neurogenic lesions
  - myopathies

NERVE CONDUCTION VELOCITY
- assess large myelinated fibers
- focal compression & demyelination leads to slowing of
NCV

Question 17

When is non-operative treatment indicated?

Answer 17

• neuropraxia
• axonotmesis
• gunshot wounds affecting brachial plexus

OBSERVE WITH EMG for 3 months

Question 18

When is surgical repair indicated in nerve injuries?

Answer 18

neurotmesis

• early surgical exploration in case of
  - penetrating trauma
  - iatrogenic injury
  - vascular injury
  - progressive deficits

Question 19

When is nerve grafting indicated?

Answer 19

• in gaps that prevent tension-free direct repair

Question 20

What are the types of operative treatment in nerve injuries?

Answer 20

• surgical repair
• nerve grafting
• nerve transfer
• tendon transfer