Peripheral Nerve Injury Flashcards
Peripheral nerve injury may result in what impairments?
motor, sensory, or sympathetic function
What are the two mechanisms of pain caused by a peripheral nerve injury?
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
What are the mechanisms of nerve injury?
compression, laceration, stretch, radiation, electricity
Briefly describe compression injury to a nerve.
sustained pressure applied externally (i.e. tourniquet) or internally (i.e. bone, tumor, impingement) and mechanical or ischemic injury
Give some examples of a laceration injury to a nerve.
GSW, knife, surgical complication, injection injury
Briefly describe stretch injury to a nerve.
excessive tension, tearing from traction forces
Name a couple examples of electrical injury to a peripheral nerve.
lightening strike, electrical malfunction
What type affects the conducting tissues or connective tissue of the nerve, that may restrict the elasticity of the NS?
intraneural
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?
extraneural
According to the Seddon classification, what is the result of mild ischemia from compression or traction?
neuropraxia
According to the Seddon classification, what is the result of prolonged compression or stretch causing infarction and necrosis?
axontmesis
According to the Seddon classification, what is the result of laceration, avulsion, or rupture?
neurotmesis
Match the term with the correct description.
a. neuroproxia
b. axontmesis
c. neurotmesis
- 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
- 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
- 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
a = 2, b = 3, c = 1
When a nerve has been injured, recovery is dependent on what factors?
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
Describe the recovery of a nerve relative to the nature of the injury.
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
Describe the recovery of a nerve relative to the level of injury.
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
Describe the recovery of a nerve relative to the timing and technique of surgical repair.
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
Describe the recovery of a nerve relative to the regenerative potential involved.
Radial, musculocutaneous, and femoral nerves have excellent potential;
median, ulnar, and tibial nerves have moderate potential;
peroneal nerve has poor potential
Describe the recovery of a nerve relative to the motivation and age.
NS must adapt and relearn use of pathways once regeneration occurs so motivation and age play a role - especially in very young and elderly
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
d is wrong = wrong territory
b - is due to degeneration of end organ
c results in improper input results
Describe the management of an acute nerve injury.
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
Describe the mangament of a recovering nerve injury.
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
What are the preventative measures to prevent reinjury?
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
Describe the management of a chronic nerve injury.
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)
