PNS Injury/Repair N30

Question 1

Neuropraxia

Answer 1

acute insult to peripheral nerve resulting in interruption of impulse transmission

Question 2

Neuropraxia exam results

Answer 2

partial loss of sensory and motor

Question 3

Neuropraxia causes

Answer 3

Microvascular alteration resulting in transient ischemia, reversible, compression of nerve

Question 4

Axonotmesis

Answer 4

injury to axoplasm and cell membrane but Schwann cell and CT are intact

Question 5

Axonotmesis causes

Answer 5

long bone fracture and traction injury

Question 6

Axonotmesis exam results

Answer 6

partial loss of sensory and motor to areas innervated by damaged neuron(s) and neurogenic atrophy due to irreversible absence of electrical potentials

Question 7

Histological change with Axonotmesis

Answer 7

regression of myelin, thickening of epineurium, scar tissue, neuroma

Question 8

Neurotmesis

Answer 8

complete severance of peripheral nerve trunk

Question 9

Neurotmesis exam results

Answer 9

complete loss of sensory and motor to innervated areas

Question 10

Histological change with Neurotmesis

Answer 10

degeneration of axons distally, degeneration for 1-2 nodes proximal

Question 11

Lesion in continuity has a greater chance of regeneration

Answer 11

meaning: when the epineurium and supporting structures are intact to maintain continuity between the severed nerve, regenertion may be likely

Question 12

Neuronal cell body’s reaction to injury

Answer 12

hypertrophy to induce metabolic processes required for regeneration (greatest chance for regeneration: minor lesion nerve proximal to cell body)

Question 13

The proximal nerve stump’s reaction to injury

Answer 13

retraction (elasticity), degeneration (2-3 nodes), hemorrhaging and clot followed by macrophage invasion, possible neuroma, SCHWANN CELL proliferation to meet distal stump and create a glial tunnel to guide the regenerating axon

Question 14

The distal nerve stump’s reaction to injury

Answer 14

WALLERIAN DEGENERATION of axon, macrophage invasion, Schwann cell activity diminishes, CT beings to proliferate, regeneration occurs via extension of Schwann cells and CT provide pathway

Question 15

Factors that contribute to healing

Answer 15

Intrinsic: age, health, time since injury, type of injury, level and nerves involved
Extrinsic: surgical technique

Question 16

Surgical repair of nerves: Immediate repair

Answer 16

8-12 hrs following injury, full or partial transection of nerve, clean, sharp wound

Question 17

Surgical repair of nerves: Delayed repair

Answer 17

2-6 weeks following injury, trauma or infection, time for inflammation to subside, time for metabolism of nerve body to change

Question 18

End-to-end surgical repair

Answer 18

suture the proximal and distal epineurium together

Question 19

End-to-side repair

Answer 19

epineurium of distal stump is sutured to an undamaged nerve

Question 20

Nerve cuffs to repair nerve lesion

Answer 20

cuff made of various materials to close off the surgical regeneration site and prevent misguidance of axons and ingrowth of CT

Question 21

Nerve grafts

Answer 21

if a nerve gap exists (due to damage) a nerve may be stretched 2-3cm to fill gap, otherwise a nerve graft from biological or biocompatible materials are used to bridge the gap

Question 22

Skeletal muscle atrophy

Answer 22

occurs if nerve innervation isn’t restored within a certain time frame; IRREVERSIBLE