EMG Sachen

Question 1

needle emg

Answer 1

muscle studies at rest and at different levels of sustained, voluntary contraction

at rest should be silent, any spont acitivity may signal nerve or muslce abnormality

during activity, shape and pattern can distinguish btwn nerve and muscle disesae

Question 2

measure of conduction time from stimulation across nerve segment through NMJ to inital activation of m fiber

Answer 2

motor latency

Question 3

needle EMG, grading of spontaneous activity
0
\+/-
1
2
3
4

Answer 3

0 = no fibs/PSWs
+/- fibs/PSWs that are not persistent
1+ persistent fibs/PSWs in at least 2 areas
2+ persistent fibs/PSWs of moderate #s in three or more areas
3+ persistent fibs/PSWs of large #s but not obscuring baseline
4+ baseline obliterated in all areas examined

Question 4

interference patterns

Answer 4

motor unit pattern with full voluntary activation

Question 5

measure of conduction time of action potential from stiumlation across nerve segment

Answer 5

sensory latency

Question 6

meausre of the velocity of the fastest conducting axons

Answer 6

conduction velocity

Question 7

nerve conduction studies

Answer 7

periph nerves (m and S) stimulated with controlled electrical stimulus

record:
compound motor action potential 
sensory nerve action potential
F wave latency measures
H reflex

Question 8

needle emg parameters evaluated

Answer 8

insertional activity

spontaneous activity

• nerve or muscle disesae
• fibrillations, postive, positive sharp waves (point down), fasiculations
• hallmark of denervation, muscle membrane irritation

motor unit config
motor unit recruit
interference patterns

Question 9

utility of an EDX medicine consultation

Answer 9

clarify etiology of symptoms 
localize PNS lesion
assist in therapeutic decision making
predict neurological prog
exclude other disorders

Question 10

measure of number of activated muscle fibers

Answer 10

motor amplitude

Question 11

components of EMX

Answer 11

nerve conduction studies
electromyography
special test (repetitive nerve stimulation, single fiber evaluation)

Question 12

motor axon and all its muscle fibers

Answer 12

single motor unit

Question 13

emg pearls

Answer 13

edx studies are a supplement to, and not replacement for history and physical

edx results are often time dependent

edx studies are not standarized

Question 14

measure of number of activated sensroy axons

Answer 14

sensory amplitude