Nerve Conduction Studies

Question 1

PT produces the AP conducted along a peripheral nerve

Answer 1

NCS

Question 2

pt activates mm for PT to determine response to the pt’s AP

Answer 2

EMG

Question 3

Active recording electrode (cathode) placement during motor study.

Answer 3

over distal-most superficial innervated mm in nerve to be examined

Question 4

inactive/reference (anode (red)) placement during motor study

Answer 4

over distal bony prominence/tendon

Question 5

Order of stimulating electrodes in motor set up

Answer 5

cathode points more distally

Question 6

latency

Answer 6

time interval between stimulation and the onset of the contraction reported in ms

Question 7

distal latency

Answer 7

distal most stimulation site-S1. determined by conduction velocity of the nerve, neuromuscular jx and mm

Question 8

amplitude

Answer 8

baseline to peak measurement. reflects number of axons in a nerve that conducted the evoked/AP.reported in mV (motor) or MicroV (sensory)

Question 9

duration

Answer 9

time it takes for evoked potential onset to return to baseline. reported in ms

Question 10

CMAP latency represents what 3 separate processes

Answer 10

1. time it takes the axon to conduct from point of stimulaiton
2. time delay to release ACh at MEP
3. Time it takes mm to depolarize