Emg Normal Values

Front 1

Normal Median Palmar Sensory Amplitude?

Back 1

>40 uV

Front 2

Normal Median Digital Sensory (2nd) Amp?

Back 2

>15 uV

Front 3

Normal Ulnar Plamar Sensory Amp?

Back 3

>11 uV

Front 4

Normal Ulnar Dig Sensory (5th) Amp?

Back 4

>5 uV

Front 5

Normal Radial Sensory Amp?

Back 5

>15 uV

Front 6

Normal Median Motor Amp?

Back 6

>3 mV

Front 7

Normal Ulnar Motor Amp?

Back 7

>5 mV

Front 8

Normal Peroneal Motor Amp?

Back 8

>2 mV

Front 9

Normal Tibial Motor Amp?

Back 9

>2 mV

Front 10

Normal Sural Sensory Amp?

Back 10

>5 uV

Front 11

Normal Median Palmar Sensory Latency?

Back 11

<2.3 ms

Front 12

Normal Median Dig Sensory (2nd) Latency?

Back 12

<3.7 ms

Front 13

Normal Ulnar Palmar Sensory Latency?

Back 13

< 2.2 ms

Front 14

Normal Ulnar Dig Sensory (5th) Latency?

Back 14

< 3.1 ms

Front 15

Normal Radial Sensory Latency?

Back 15

< 2.5 ms

Front 16

Normal Median Motor Latency?

Back 16

< 4.5 ms

Front 17

Normal Ulnar Motor Latency?

Back 17

<3.6 ms

Front 18

Normal Peroneal Motor Latency?

Back 18

< 6.6 ms

Front 19

Normal Tibial Motor Latency?

Back 19

< 6.6 ms

Front 20

Normal Sural Sensory Latency over 30?

Back 20

< 4.8 ms

Front 21

Normal Sural Sensory Latency under 30?

Back 21

<4.2 ms

Front 22

Normal Median palm sensory distance?

Back 22

8 cm

Front 23

Normal median dig sensory (2nd) distance?

Back 23

13 cm

Front 24

Normal ulnar palm sensory distance?

Back 24

8 cm

Front 25

Normal Ulnar dig sensory (5th) distance?

Back 25

11 cm

Front 26

Normal radial sensory distance?

Back 26

10 cm

Front 27

Normal median motor distance?

Back 27

7 cm

Front 28

Normal ulnar motor distance?

Back 28

7 cm

Front 29

Normal peroneal motor distance?

Back 29

8 cm

Front 30

Normal tibial motor distance?

Back 30

12 cm

Front 31

Normal sural sensory distance?

Back 31

14 cm

Front 32

Normal Upper extremity conduction velocity?

Back 32

>48 m/sec

Front 33

Normal Lower extremity conduction velocity?

Back 33

>42 m/sec

Front 34

Temperature range should be between 33-35 C. Each degree C below this, can make a _____ difference in conduction velocity?

Back 34

2 m/sec

Front 35

For each centimeter off in distance, there is a _____difference in latency?

Back 35

0.15 ms

Front 36

Grade I carpal tunnel syndrome is defined as _____

Back 36

>/= 0.5 ms difference between median and ulnar latency.

Front 37

Grade II CTS is considered moderate and defined as ___

Back 37

prolonged sensory

Front 38

Grade III CTS is considered moderate to severe disease and is defined as _________

Back 38

prolonged sensory AND prolonged motor

Front 39

Grade IV CTS is considered severe disease and is defined as _______________

Back 39

prolonged sensory and motor AND abnormal needle exam.

Front 40

Gain is set at _____ to ____ for motor NCS/

Back 40

2 mV to 5 mV per division

Front 41

Recording electrode is placed over muscle belly and the reference electrode is placed ____.

Back 41

Distally over the tendon

Front 42

duration of the electrical pulse in motor NCS is set to ____ms

Back 42

200 ms

Front 43

Normal nerve require a current in the range of ___ to ___ mA to achieve supramaximal stimulation.

Back 43

20 to 50 mA

Front 44

Current is slowly increased from a baseline of 0 mA by 5 to 10 mA to bring in more underlying nerve fibers generating a CMAP. When do you stop increasing current?

Back 44

20% further once observed CMAP no longer increases in size

Front 45

CMAP should be a ______ wave in which the initial deflection is upward (negative).

Back 45

Biphasic

Front 46

Latency represents these three separate processes?

Back 46

1) nerve conduction time from stimulus site to NMJ
2) Time delay across the NMJ
3) Depolarization time across the muscle

Front 47

Latency measurements are made in "ms" and reflect ____

Back 47

only the fastest conducting motor fibers

Front 48

Amplitude is measured from ___to the ____

Back 48

baseline to the negative peak

Front 49

CMAP amp reflects ________

Back 49

number of muscle fibers that depolarize

Front 50

Low CMAP amplitudes most often result from ______

Back 50

loss of axons

Front 51

While not the most common cause for Low CMAP amp, low CMAP Amp can also occur in setting of ______, ____ and _____

Back 51

conduction block from demyelination, some NMJ disorders and myopathies

Front 52

CMAP duration is measured from ____ to ___

Back 52

from initial deflection from baseline to the first baseline crossing (ie negative peak duration)

Front 53

Duration of CMAP is a measure of ______

Back 53

synchrony (ie the extent to which each of the individual muscle fibers fire at the same time)

Front 54

Duration of CMAP characteristically increases in conditions that result in slowing of some motor fibers but not others as in _________

Back 54

demyelinating lesions

Front 55

Proximal latency is _____ than distal latency

Back 55

longer

Front 56

Distal motor latency includes _____, _____ and ____.

Back 56

1) conduction time along the distal motor axon to the NMJ
2) NMJ transmission time
3) muscle depolarization time

Front 57

Proximal motor latency includes the same three factors in distal motor latency plus _____

Back 57

nerve conduction time between the proximal and distal stimulation sites

Front 58

Latency and conduction velocity only reflect the ______ fibers

Back 58

fastest conducting

Front 59

Slower conducting fibers participate in CMAP area and amplitude but are not reflected in ____ or ___.

Back 59

latency or conduction velocity

Front 60

For sensory NCS pulse of other 100 or 200 ms in duration is used with current range of ___ to ___ to achieve supramaximal stimulation in most normal nerves?

Back 60

5 mA to 30 mA

Front 61

Sensory nerve action potentials (SNAPs) are usually ___ or ____ waves?

Back 61

biphasic or triphasic

Front 62

Onset latency is measured from ___ to ___

Back 62

stimulus to the initial negative deflection from baseline for biphasic SNAPS or to the initial positive peak for triphasics SNAPs

Front 63

Peak latency is measured at ____ of the first negative peak

Back 63

midpoint

Front 64

the SNAP amplitude reflects the sum of all the _____

Back 64

individual sensory fibers that depolarize

Front 65

distance traveled divided by onset latency gives you this value in the Sensory NCS

Back 65

conduction velocity

Front 66

Axonal loss is evident by reduction in this parameter of NCS?

Back 66

reduced amplitude

Front 67

In axonal loss lesions, _____ and ____ are normal, provided that the largest and fastest conducting axons remain intact.

Back 67

conduction velocity and distal latency

Front 68

The typical pattern associated with axonal loss is one of ____ and preserved ______ and ______

Back 68

reduced amplitudes and preserved latency and conduction velocities

Front 69

with axonal loss lesions amplitudes decrease, conduction velocities are normal or slightly decreased BUT NEVER BELOW _____ of the lower limit of normal

Back 69

75%

Front 70

with axonal loss lesions amplitudes decrease and distal latencies are normal or slightly prolonged BUT NEVER GREATER THAN ________ of upper limit of normal

Back 70

130%

Front 71

on NCSs demyelination is associated with marked slowing of _____ and marked prolongation of _____

Back 71

slowing of conduction velocity (slower than 75% of lower limit or normal) and prolongation of distal latency (longer than 130% of upper limit or normal)

Front 72

Any motor, sensory or mixd nerve conduction velocity that is slower than ____ m/s in the arms or ____ m/s in the legs signifies unequivocal demyelination.

Back 72

slower than 35 m/s in arms and 30 m/s in legs

Front 73

reduced amplitudes in demyelinating lesions are seen when _______ is present

Back 73

conduction block

Front 74

A drop in CMAP area between proximal and distal stimulation of more than ____% denotes conduction block

Back 74

%50

Front 75

A drop in CMAP amplitude of more than ____% denotes a conduction block

Back 75

20%