nerve damage

Question 1

which part of the neurone is able to repair and which isn’t

Answer 1

bodies - cant NO TREATMENT

nerve endings - can LIMITED TREATMENT

Question 2

describe the role os schwann cells in myelinated and unmyelinated fibres

Answer 2

myelinated schwann cell all the way around 1 per axon individually
unmyelinated wrapping around 5 or so axons

Question 3

what is endoneurium

Answer 3

microenvironment continuous with subarachnoid space

Question 4

order of neureums in a nerve

Answer 4

epineureum perineureum endoneurium

Question 5

name the 2 ways damage to a nerve fibre can occur

Answer 5

1. direcly via the axon - axonopathy
2. indirectly via the schwann cell - myelinopathy
3. indirectly via the endoneurium - neurovascularpathy

Question 6

define mononeuropathy
mononeuritis multiplex
polyneuropathy

Answer 6

= damage to only one nerve
= affecting two or more isolated nerves in separate areas
= affecting multiple nerves

Question 7

causes of peripheral neuropathy

Answer 7

idiopathic
inherited
acquired: trauma, infection, disease (diabetes) toxins

Question 8

What is the grading of nerve injury?

Answer 8

grade 1 - temp and reversible (neuropraxia) - grade 5 complete nn transection (neurotmesis)

Question 9

what is axonotmesis

Answer 9

loss of axon continuity - graded 2-5

Question 10

what is Wallerian degeneration

Answer 10

the distal stump undergoes complete
fragmentation, the rate of which is dependent
on
• the type of injury
• the site of injury (PNS&raquo_space; CNS)
• the diameter of the axon
Schwann cells remain as hollow tube
They then dedifferentiate and proliferate
These columns of reactive Schwann cells
(bands of Büngner) become important guides
for sprouting axons during reinnervation.

Question 11

how do nerve cells regenerate

Answer 11

the proximal axon stump grows along the band of bugner

Question 12

what does nn cell regrowth depend on

Answer 12

guidance by schwann cells

Question 13

what happens to schwann cells following axotopy

Answer 13

change their phenotype

• decrease myelin related proteins
• increased adhension related proteins

Question 14

what happens if the gap in the nn becomes greater than 10 mm during regrowth

Answer 14

neuroma

Question 15

surgical ways of repairing nn damage

Answer 15

1. end to end closure if gap 2cm
2. nerve grafting from small cutanous nn
3. condutis - synthetic tubes nonneural tissue

Question 16

describe 4 challenges in the clinical practice of nerve repair

Answer 16

1. misgrowth
2. slow growth so target organ dies
3. ss nn used for grafting to mm nn
4. scar tissue formation

Question 17

name 3 factors which affect the end result of end to end nn surgical repair

Answer 17

age of patient
type of laceration - sharp better
where it is - peripheral repair better

Question 18

what happenes after nn damage in the CNS?

Answer 18

astrocytes inhibit repair

Question 19

what is Reactive astrogliosis

Answer 19

astrocytes secreate inhib factors and growth factors to minimise damage (inhib have more effect)

Question 20

what is a glial scar and what accompanies it

Answer 20

astrocytes make this to isolate damage area. accompanied by CSF filled cyst

Question 21

when do axons regenerate

Answer 21

newborns, DRP

Question 22

2 reasons axon regen in the cns fails

Answer 22

surroungings inhib

feeble attempt

Question 23

why does the cns have growth inhibition

Answer 23

to stop nn growing when theyre not meant to - keep complexity