EDx Pathophysiology Flashcards
Which nerve injury has axonal interruption with intact connective tissue and conduction failure
Axonotmesis
Which type of axonal injury goes from proximal to distal
Wallerian degeneration
3 types of nerve injury according to seddon
Neuropraxia, axonotmesis, neurotmesis
effect on insertional activity, resting activity, recruitment and MUAP seen in demyelination
Insertional activity = normal
Resting activity = normal
Recruitment = normal or decreased
MUAP = normal
Etiology of neuropraxia vs axonotmesis vs neurotmesis
Neuropraxia = compression Axonotmesis = crush Neurotmesis = transection
Rate of axonal regrowth
1mm per day, 1 inch per month, 1 foot per year
Which nerve injury has normal EMG and which has abnormal EMG
Normal = neuropraxia Abnormal = axonotmesis and neurotmesis
What does collateral sprouting do to the wave forms
Polyphasic with increased amplitudes
Axonal injury can result in 2 different forms:
Wallerian degeneration and axonal degeneration
5 types of sunderland classification
1 = conduction block (neuropraxia) 2 = axonal injury (axonotmesis) 3= endoneurium injury 4= perineurium injury 5= epineurium injury
Chance of successful surgical repair decreases after how long after injury
6 months
Which nerve injury has axonal interruption with disruption of connective tissue and conduction failure
Neurotmesis
Which type of axonal injury goes from distal to proximal
Axonal degeneration
Process of repair where dendrites sprouts of axons from an intact motor unit and innervates denervated muscle fibers of injured motor units
Collateral sprouting
4 causes of axonal injury
- Crush
- Stretch
- Neuropathy
- Transection
Failure of AP to propagate past an area of demyelination
Conduction block
Chance of successful surgical repair decreases with proximal or distal nerve injury?
Proximal
After axonal regrowth, what happens to amplitude, duration and phases?
Amplitude = decreased Duration = longer phases = polyphasic
effect on insertional activity, resting activity, recruitment and MUAP seen in axonal injury
Insertional activity = abnormal
Resting activity = abnormal
Recruitment = decreased
MuAP = abnormal
Effect on latency, conduction velocity, temporal dispersion, and amplitude in axonal injury seen on NCS
Latency = normal
Conduction velocity = mildly decreased
Temporal dispersion = normal
Amplitude = Decreased
Conduction block can result in a _______ in CMAP amplitude
50% decrease
Surgery is indicated for nerve injuries when there is no return in function after how long
2 months for peripheral nerve injuries and 4 months for brachial plexus injuries
Chance of successful surgical repair decreases with how much of a nerve gap
> 2.5 cm
Effect on latency, conduction velocity, temporal dispersion, and amplitude in demyelination seen on NCS
Latency = prolonged
CV = decreased
Temporal dispersion = increased
Amplitude = decreased
Which nerve injury has myelin injury with intact axon and conduction block
Neuropraxia
