EDX

Question 1

What’s an EDX? What is it composed of?

Answer 1

Electrodiagnostic examination (testing used to assess the function and integrity of the PNS)

NCS (nerve conduction studies)
Needle EMG (electromyography)
Others

Question 2

Complaints that suggest neuromuscular or MSK pathology?

Answer 2

Numbness and tingling, dec sensation, pain, cramping or spasms, weakness, gait difficulty, fatigue

Question 3

What’s involved in a nerve conduction study?

Answer 3

Peripheral nerves are stimulated w/ a controlled electrical stimulus to get a response

Responses: motor (CMAP), sensory (SNAP)

Question 4

Define motor latency.

Answer 4

Measure of conduction time from stimulation to initial activation of muscle fibers

Question 5

Define motor amplitude.

Answer 5

Measure of the number of activated muscle fibers

Question 6

Define sensory latency.

Answer 6

Measure of conduction time of AP from stimulation across a n segment

Question 7

Define sensory amplitude.

Answer 7

Measure of the number of activated sensory axons

Question 8

Define conduction velocity.

Answer 8

Measure of the velocity of the fastest conducting axons (motor and sensory)

Question 9

What’s a Needle EMG (elecromyography)? What’s normal at rest?

Answer 9

Needle (single use) electrode is inserted into the muscle

Muscle is studied at rest and different levels of sustained voluntary contraction

Silence, activity is abnormal

Question 10

What parameters are being evaluated in a Needle EMG?

Answer 10

Insertional activity (needle insert causes burst of activity d/t m fiber disruption, prolonged = dx)
Spontaneous activity (fibrillations, pos sharp waves, fasciculations, hallmark of denervation/membrane irritation)
Motor unit configuration (amplitude, duration, morphology)
Motor unit recruitment (pattern of motor unit activation w/ inc volitional activation)
Interference pattern (motor unit pattern w/ full voluntary activation)

Question 11

Spontaneous activity is seen on a needle EMG, what’s this mean?

Answer 11

It’s a hallmark of denervation, muscle membrane irritation

Question 12

How are needle EMGs graded?

Answer 12

0 = no fibs/PSWs (positive sharp waves)
\+/- = fibs/PSWs that aren't persistent
1+ = fibs/PSWs in 2 areas
2+ = fibs/PSWs in 3 or more areas
3+ = fibs/PSWs of large #s but the baseline is not obscured
4+ = baseline obscured

Question 13

What’s a motor unit?

Answer 13

Motor axon and all its muscle fibers