Musculoskeletal Growth Injury and Repair – Peripheral Nerve Injuries

Question 1

What are the two units of a nerve…worded that weird but you know it

Answer 1

Motor and sensory units

Question 2

What are the motor units (efferent) and where are they located?

Answer 2

Anterior horn cells found in grey matter of spinal cord

Question 3

What are the sensory units (afferent) and where are they located?

Answer 3

Cell bodies in the posterior root ganglia i.e. outside of the spinal cord

Question 4

Nerve fibres joint to form motor and sensory roots. Are the sensory roots anterior or posterior and ventral or dorsal?

Answer 4

Posterior/dorsal roots

Question 5

Nerve fibres joint to form motor and sensory roots. Are the motor roots anterior or posterior and ventral or dorsal?

Answer 5

Anterior/ventral roots

Question 6

What surrounds larger peripheral nerve fibres?

Answer 6

Myelin sheath which provides insulation

Question 7

What are axons coated with?

Answer 7

Endoneurium - type of CT

Question 8

What are axons grouped together to form?

Answer 8

A fascicle

Question 9

What are fascicles grouped together to form?

Answer 9

Nerve

Question 10

What type of CT covers nerves?

Answer 10

Epineurium

Question 11

What cells surround neurones?

Answer 11

Schwann cells

Question 12

RECAP- which type of fibres travel the quickest?

Answer 12

A alpha fibres

->these are the biggest fibres

Question 13

RECAP- which type of fibres travel the slowest?

Answer 13

C fibres

->these are the smaller fibres

Question 14

Which fibres transmit dull, aching or burning pain and temperature sensation?

Answer 14

C fibres

Question 15

Which fibres transmit sharp pain and light touch?

Answer 15

A delta fibres

Question 16

Which fibres transmit touch, pressure, vibration and join position sensory axons?

Answer 16

A beta fibres

Question 17

Give some examples of direct trauma injuries.

Answer 17

Blow or laceration

Question 18

Give some examples of indirect trauma injuries.

Answer 18

Avulsion or traction

Question 19

List some common conditions caused by compression of a nerve.

Answer 19

Carpal tunnel syndrome
Sciatica
Morton’s neuroma

Question 20

Which nerve gets compressed in carpal tunnel syndrome?

Answer 20

Median nerve

Question 21

Which nerves get compressed in sciatica?

Answer 21

Spinal roots by IV discs

Question 22

What nerve get compressed in Morton’s neuroma?

Answer 22

Digital nerve in 2nd or 3rd web space of forefoot

Question 23

Neurapraxia?

Answer 23

Mild nerve injury in which nerve has been stretched or bruised

Causes conduction block and local ischaemia and demyelination

Question 24

What is prognosis of neurapraxia?

Answer 24

Good as reversible, settles after weeks or month

Question 25

Axonotmesis?

Answer 25

More severe than neuropraxia, nerve is more stretched
Wallerian degeneration follows

Question 26

What is the prognosis of axonotmesis like?

Answer 26

Fair, sensory recovery is often better than the motor recovery but is still not normal but enough to recognise hot and cold, sharp and blunt etc

Question 27

Neutrotmesis?

Answer 27

Worse than axonotmesis and neuropraxia.
Often caused by lactation or avulsion

Question 28

What is the prognosis of neurotmesis like?

Answer 28

No recovery unless repaired by suturing or grafting
Poor porgnosis

Question 29

Nerve injuries are be described as being open or closed. Closed nerve injuries are associated with nerve injuries in continuity (whole nerve is still in tact). Give examples

Answer 29

Neuropraxis
Axonotmesis

Question 30

How long after closed nerve injuries in surgery indicated?

Answer 30

3 months after as spontaneous recovery in possible

Question 31

What are open nerve injuries usually associated with?

Answer 31

Trauma e.g. knives or glass cutting through a nerve

Question 32

How are open nerve injuries usually treated?

Answer 32

Early surgery

Question 33

What are the clinical features of nerve injuries?

Answer 33

Sensory- numbness and paraesthesia
Motor- weakness, paralysis, wasting, dry skin
Diminished or absent reflexes

Question 34

Do pure or mixed nerves tend to recover better?

Answer 34

Pure nerves (only sensory or motor)

Question 35

Which sign can be used to monitor recovery in nerve injuries?

Answer 35

Tinel’s sign

->tap over nerve site and paraesthesia will be felt as far distally as nerve regeneration has progressed. We do this in clinical skills for carpal tunnel syndrome).

Question 36

How quickly do nerves regenerate?

Answer 36

1mm/day

Question 37

What are the two ways of surgically repairing a nerve?

Answer 37

Direct repair
Nerve grating

Question 38

When can nerves be directly repaired?

Answer 38

In laceration if two nerve endings present

Question 39

When is nerve grafting used?

Answer 39

When there is nerve loss of it’s a late repair after a few months after injury

Question 40

Injuries to peripheral and central NS can both cause loss of motor or sensory function or both.
So how can we tell the difference clinically?

Answer 40

UMN vs LMN lesions as in UMN lesions, the peripheral nerve is still intact

Question 41

RECAP- UMN lesion findings?

Answer 41

Decreased strength
Increased tone
Increased reflexes
Present Babinski’s sign
Clonus

Question 42

REACP- LMN lesion findings?

Answer 42

Muscle atrophy
Decreased reflexes
Absent Babinski’s sign