Lecture 10

Question 1

name the layers in a nerve (4)

Answer 1

outside to inside :
- mesoneurium
- epineurium
- perineurium
- endoneurium

Question 2

how do you define a nerve injury ?

Answer 2

= interruption of function through noxious agents.
- injury (cut, fracture, …)
- iatrogenic
- contusion / pressure / traction
- physical lesions (chemical, electrical, …)

Question 3

explain pathophysiology of nerve injury (waller’s degeneration)

Answer 3

Distal end retracts (waller)
Destruction of cell
Proximal : degeneration

Question 4

peripheral nerve injury : how frequent, 2 repair strategies, complete recovery ?

Answer 4

over 300’000 per year in europe.
Primarily sutured or grafted with another nerve.
Complete recovery not possible (some loss of sensation and motor function)

Question 5

3 ways to repair a nerve injury (requirements)

Answer 5

1) primary suture : cut needs to be clean, needs to be tensionless !!
2) autologous graft : donor site morbidity, scarring pain (neuroma)
3) nerve conduit : guiding structure for growth, with added neurotrophic factors to help

Question 6

nerve conduits : 2 material examples, how can we optimize the conduits ?

Answer 6

PHB
Fibrin (better than PHB)

Fibrin matrix supplemented with adipose-derived stem cells (differentiate into schwann-like cells) or Schwann cells to promote neurite growth

Question 7

are adipose cells from superficial fat layer or deep fat layer better for supporting nerve repair ?

Answer 7

superficial adipose layer cells are better

Question 8

what is one advantage of using fibrin ?

Answer 8

it is resorbed by the body -> no foreign body remains at the end

Question 9

clinical classification of nerve injury : 3 levels

Answer 9

1) neurapraxia (traction) : continuity maintained but segmental demyelination -> reversible within months

2) axonotmesis : neurapraxia with myelin loss, perineurium preserved, regeneration takes longer than 1)

3) neurotmesis : complete nerve separation, surgery needed

Question 10

4 things a doctor does in clinical neuroligical examinations

Answer 10

• sensitivity testing
• motor function testing
• inspection of wound (if fresh injury)
• electroneurography / nerve sonography

Question 11

name some sources of error in nerve transplants

Answer 11

• insufficient nerve preparation
• tension
• too many sutures -> fibrosis
• nerve interponates are too short

Question 12

name some complications i nerve transplation surgery

Answer 12

• bleeding
• tearing of suture
• fibrosis
• neuroma formation (overgrowth)
• nerve constriction due to scar tissue
• donor site morbidity

Question 13

what is a neurotization ?

Answer 13

= a healthy but less valuable nerve or its proximal stump is transferred in order to reinnervate a more important sensory or motor territory

Question 14

examples of sensory, motor and sensory-motor neurotizations

Answer 14

1) cornea, breast reconstruction

2) hand, lower limb, tetraplegic

3) erectile dysfunction

Question 15

what is meant by fascicular shift ?

Answer 15

only take a piece of the donor nerve (some fascicles) -> no additional donor site morbidity

Question 16

what can be done in the case of very painful neuromas ?

Answer 16

Prevent the nerve from growing by suturing to itself or to a muscle

Question 17

what can be done in certain chronic headaches ?

Answer 17

nerve decompression -> risk of scar tissue which would compress the nerve again