Peripheral Nerve Injury

Question 1

Peripheral nerve injury may result in what impairments?

Answer 1

motor, sensory, or sympathetic function

Question 2

What are the two mechanisms of pain caused by a peripheral nerve injury?

Answer 2

involvement of connective tissue and vascular structures surrounding/in the peripheral nerves;
alterations in impulse conduction fro excess mechanical loading and inflammation - can contribute to burning, tingling, shocklike spontaneous pain

Question 3

What are the mechanisms of nerve injury?

Answer 3

compression, laceration, stretch, radiation, electricity

Question 4

Briefly describe compression injury to a nerve.

Answer 4

sustained pressure applied externally (i.e. tourniquet) or internally (i.e. bone, tumor, impingement) and mechanical or ischemic injury

Question 5

Give some examples of a laceration injury to a nerve.

Answer 5

GSW, knife, surgical complication, injection injury

Question 6

Briefly describe stretch injury to a nerve.

Answer 6

excessive tension, tearing from traction forces

Question 7

Name a couple examples of electrical injury to a peripheral nerve.

Answer 7

lightening strike, electrical malfunction

Question 8

What type affects the conducting tissues or connective tissue of the nerve, that may restrict the elasticity of the NS?

Answer 8

intraneural

Question 9

What type affects the nerve bed, adhesions of epineurium to another tissue, and swelling of the tissue adj to the nerve, that may restrict the gross movement of NS in relation to surrounding tissues?

Answer 9

extraneural

Question 10

According to the Seddon classification, what is the result of mild ischemia from compression or traction?

Answer 10

neuropraxia

Question 11

According to the Seddon classification, what is the result of prolonged compression or stretch causing infarction and necrosis?

Answer 11

axontmesis

Question 12

According to the Seddon classification, what is the result of laceration, avulsion, or rupture?

Answer 12

neurotmesis

Question 13

Match the term with the correct description.

a. neuroproxia
b. axontmesis
c. neurotmesis

1. complete severance of nerve fiber with disription of CT coverings, wallerian degeneration distal to lesion, muscle fiber atrophy and sensory loss, no recovery without surgery
2. segmental demyelination, AP slowed/blocked at point of demyelination, normal above and below point of compression, muscle doesn’t atrophy, temporary sensory symptoms, recovery is usually complete
3. loss of axonal continuity but CT coverings remain intact, Wallerian degeneration distal to lesion, muscle fiber atrophy and sensory loss, recovery is usually incomplete- may require surgery

Answer 13

a = 2, b = 3, c = 1

Question 14

When a nerve has been injured, recovery is dependent on what factors?

Answer 14

extent of injury to axon and surround tissue sheath, nature and level of injury, timing and technique of repair, the age and motivation of the person, and the regenerative potential of involved nerve

Question 15

Describe the recovery of a nerve relative to the nature of the injury.

Answer 15

the more damage to the nerve and tissues, the more tissue reaction and scarring occur;
the proximal aspect of a nerve has greater combinations of motor, sensory, and sympathetic fibers so disruption there results in greater chance of mismatch

Question 16

Describe the recovery of a nerve relative to the level of injury.

Answer 16

occurs at a rate of 1 inch per month but rates from 0.5-9.0 mm have been reported based on severity, nature, duration and condition

Question 17

Describe the recovery of a nerve relative to the timing and technique of surgical repair.

Answer 17

laceration or crush that disrupts the integrity of the entire nerve require surgical repair for optimal regeneration, timing of repair is critical as well as skill of surgeon and technique used

Question 18

Describe the recovery of a nerve relative to the regenerative potential involved.

Answer 18

Radial, musculocutaneous, and femoral nerves have excellent potential;
median, ulnar, and tibial nerves have moderate potential;
peroneal nerve has poor potential

Question 19

Describe the recovery of a nerve relative to the motivation and age.

Answer 19

NS must adapt and relearn use of pathways once regeneration occurs so motivation and age play a role - especially in very young and elderly

Question 20

Which of the following is not an accurate outcome of nerve regeneration?

a. exact reinnervation of its native target organ with return organ
b. exact reinnervation of native target organ but no return of function
c. wrong receptor reinnervated in the proper territory
d. receptor reinnervation in same territory but causing false localization of imput
e. no connection with end organ

Answer 20

d is wrong = wrong territory

b - is due to degeneration of end organ

c results in improper input results

Question 21

Describe the management of an acute nerve injury.

Answer 21

early after injury or surgery when emphasis is on healing and prevention of complications:

immobilization (time will be dictated by surgeon), movement (amount and intensity dictated by type of injury and repair), splinting or bracing may be necessary to prevent deformities, patient education for protection of the part

Question 22

Describe the mangament of a recovering nerve injury.

Answer 22

reinnervation is occurring, emphasis is on retraining and re-education:

motor retraining - muscle “hold” in shortened position - use e-stim to reinforce; desensitization - multiple textures for sensory stimulation/vibration; discrimative sensory re-education - indentification of objects with then without visual cues; patient education - resume use of extremity gradually while monitoring pain, swelling, or discoloration, and preventative care to avoid reinjury

Question 23

What are the preventative measures to prevent reinjury?

Answer 23

inspect skin regularly; aoid hot, cold, sharp, or abrasive objects; avoid sustained grasps; redistribute hand pressure by building up the size of the handles; wear protective gloves; wear protective shoes that fit properly; don’t walk barefoot; inspect feet regularly for pressure points; shift weight frequently when prolonged standing

Question 24

Describe the management of a chronic nerve injury.

Answer 24

potential for reinnervation has peaked and there is significant residual deficits - emphases is on training compensatory function and preventative care (lifelong care to involved region)