NCV

Question 1

NCV always involves a _______ response.

Answer 1

stimulated

Question 2

NCV produces a _______ potential.

Answer 2

composite

Question 3

NCV can examine ______ & ______ systems.

Answer 3

sensory and motor

can separate the two

Question 4

NCV can examine nerves in a _______ fashion.

Answer 4

segmental

Question 5

What is the purpose of NCV?

Answer 5

calculate velocity of AP conduction down nerve axons

Question 6

How is motor response evaluated?

Answer 6

stimulate surface electrodes over muscle

ORTHODROMIC nerve activation

Question 7

How is sensory response evaluated?

Answer 7

electrodes placed over finger tips or toes in areas without muscle
ANTIDROMIC nerve activation

Question 8

describe M wave

Answer 8

composite of ALL axons in the nerve and their contracting muscle fibers

Question 9

the time from stimulus artifact to beg. of M wave is called

Answer 9

conduction time

Question 10

the time from stimulation at proximal site to M wave is called

Answer 10

proximal latency

Question 11

the time from stimulation at distal site to M wave is called

Answer 11

distal latency

Question 12

What is the formula for NCV?

Answer 12

NCV = conduction distance (m) / conduction time (sec)

Question 13

conduction time = _____ latency - _____ latency

Answer 13

proximal - distal

Question 14

Why is most distal aspect of nerve omitted from NCV calculations?

Answer 14

do NOT include MU in rder to omit neurotransmitter loading times

Question 15

What gives M wave its duration?

Answer 15

not all fibers contract simultaneously

faster MUs contract first, slower second

Question 16

What causes M wave dispersion?

Answer 16

compressive neuropathy or partially reinnervated muscle

slower conduction, more myelin segments in collaterals, some MUs are not innervated

Question 17

With full degeneration or lesion, NCV values would approach

Answer 17

zero

Question 18

With pure myelin disease without axonal involvement could have _______ NCV values with no signs of EMG denervation.

Answer 18

decreased NCV

Question 19

During regeneration, NCV is slower because:

Answer 19

more myelin segments

Question 20

What is orthodronic?

Answer 20

stimulus in normal physiological direction (for motor NCV: proximal -> distal)

Question 21

What is antidromic?

Answer 21

stimulus opposite from normal physiological direction (for sensory NCV: CNS -> distal)

Question 22

Nerve root evaluation can look at both sensory and motor. What are the two elements used to evaluate?

Answer 22

H Reflex: sensory OR motor (tests ventral and dorsal roots)

F Response: motor (tests ventral root only)

Question 23

H reflex follows the same pathway as?

Answer 23

monosynaptic stretch reflex

Question 24

H reflex is only used for the ____ nerve root

Answer 24

S1

Question 25

F response activates ______ neuron.

Answer 25

alpha motor neuron

Question 26

If F response is abnormal, the H reflex must be ____.

Answer 26

abnormal

Question 27

If H reflex is slow and F response is normal, must be _______ impairment.

Answer 27

sensory

Question 28

If H reflex is slow and F response is slow, must be _______ impairment.

Answer 28

motor

but CANNOT rule of sensory

Question 29

F response is _____ response.

Answer 29

supramaximal