EDx Pathophysiology

Question 1

Which nerve injury has axonal interruption with intact connective tissue and conduction failure

Answer 1

Axonotmesis

Question 2

Which type of axonal injury goes from proximal to distal

Answer 2

Wallerian degeneration

Question 3

3 types of nerve injury according to seddon

Answer 3

Neuropraxia, axonotmesis, neurotmesis

Question 4

effect on insertional activity, resting activity, recruitment and MUAP seen in demyelination

Answer 4

Insertional activity = normal
Resting activity = normal
Recruitment = normal or decreased
MUAP = normal

Question 5

Etiology of neuropraxia vs axonotmesis vs neurotmesis

Answer 5

Neuropraxia = compression
Axonotmesis = crush
Neurotmesis = transection

Question 6

Rate of axonal regrowth

Answer 6

1mm per day, 1 inch per month, 1 foot per year

Question 7

Which nerve injury has normal EMG and which has abnormal EMG

Answer 7

Normal = neuropraxia
Abnormal = axonotmesis and neurotmesis

Question 8

What does collateral sprouting do to the wave forms

Answer 8

Polyphasic with increased amplitudes

Question 9

Axonal injury can result in 2 different forms:

Answer 9

Wallerian degeneration and axonal degeneration

Question 10

5 types of sunderland classification

Answer 10

1 = conduction block (neuropraxia)
2 = axonal injury (axonotmesis)
3= endoneurium injury
4= perineurium injury
5= epineurium injury

Question 11

Chance of successful surgical repair decreases after how long after injury

Answer 11

6 months

Question 12

Which nerve injury has axonal interruption with disruption of connective tissue and conduction failure

Answer 12

Neurotmesis

Question 13

Which type of axonal injury goes from distal to proximal

Answer 13

Axonal degeneration

Question 14

Process of repair where dendrites sprouts of axons from an intact motor unit and innervates denervated muscle fibers of injured motor units

Answer 14

Collateral sprouting

Question 15

4 causes of axonal injury

Answer 15

1. Crush
2. Stretch
3. Neuropathy
4. Transection

Question 16

Failure of AP to propagate past an area of demyelination

Answer 16

Conduction block

Question 17

Chance of successful surgical repair decreases with proximal or distal nerve injury?

Answer 17

Proximal

Question 18

After axonal regrowth, what happens to amplitude, duration and phases?

Answer 18

Amplitude = decreased
Duration = longer
phases = polyphasic

Question 19

effect on insertional activity, resting activity, recruitment and MUAP seen in axonal injury

Answer 19

Insertional activity = abnormal
Resting activity = abnormal
Recruitment = decreased
MuAP = abnormal

Question 20

Effect on latency, conduction velocity, temporal dispersion, and amplitude in axonal injury seen on NCS

Answer 20

Latency = normal
Conduction velocity = mildly decreased
Temporal dispersion = normal
Amplitude = Decreased

Question 21

Conduction block can result in a _______ in CMAP amplitude

Answer 21

50% decrease

Question 22

Surgery is indicated for nerve injuries when there is no return in function after how long

Answer 22

2 months for peripheral nerve injuries and 4 months for brachial plexus injuries

Question 23

Chance of successful surgical repair decreases with how much of a nerve gap

Answer 23

> 2.5 cm

Question 24

Effect on latency, conduction velocity, temporal dispersion, and amplitude in demyelination seen on NCS

Answer 24

Latency = prolonged
CV = decreased
Temporal dispersion = increased
Amplitude = decreased

Question 25

Which nerve injury has myelin injury with intact axon and conduction block

Answer 25

Neuropraxia