EMG Bio feedback/NCV

Question 1

EMG biofeed back in general?

Answer 1

therapeutic use of instrumentation to detect feeback from MUAP by active muscle

signal is amplified and converted

used to increase or decrease muscle activity

Question 2

Does it measure actual events occuring?

Answer 2

Measures the highly correlated events such as periperal skin temp, finger photo transmission, electromyography

Question 3

What leads to change in ion concentration

Answer 3

increased perm to sodium and potassium

Question 4

What is ion concentration measured in?

Answer 4

microvoltage by the device

Question 5

Change in electrochemical gradient created by MUAP measured by?

Answer 5

electrodes

Question 6

Which units are recruited first

Answer 6

smaller units recruited first then larger units with faster contractions may depress smalleru nits

Question 7

EMG amplification reflects

Answer 7

number of active motor units
size of motor units
distance of active mm from electrode
size of recording area
interelectrode spacing

Question 8

EMG and Force relationship

Answer 8

Isometric is linear

concentric/eccentric is nonlinear

Question 9

3 kinds of electrodes?

Answer 9

2 active electrodes

1 ground electrode

Question 10

How do we get to smoothened/integrated

Answer 10

2 active electrodes give off an amplified resultant signal that is subtracted from each other to get the amplified difference

Differential amplification removes extraneous noises
Common mode reflection ratio removes the common noise between the 2 electrode
Remaining noise is then filtered then amplified to get the raw activity (alternating) true electrical activity,

then rectified and integrated and smoothened

Question 11

Purpose of EMG

Answer 11

to change the MUAP to audiovisual to increase or decrease mm activity

Question 12

Advantages

Answer 12

immediate feedback/rewards that typically isn’t noted to allow for greater improvements

feedback without the constant supervision of the physical therapist

Question 13

Indications

Answer 13

motor inhibition
motor recruitment
total body relaxation (generalized pain/stress) goal to decrease undesired muscle tension= muscle/stress relaxation

Question 14

Contraindications

Answer 14

when mm contraction would make the condition worse

Question 15

Safe and Effective application

Answer 15

consent
select appropriate muscle group with goal
alcohol the skin
place electrodes parallel to muscle fiber belly
place ground electrode on bony prominence
set gain/sensitivty threshold, goal on EMG unit

Question 16

What can nerve conduction/EMG diagnose

Answer 16

peripheral nn lesion, mm injury, ongoing process of the neuromuscular system

establish correct diagnosis
localize lesion
determine treatment
info on prognosis

Question 17

Hardware

Answer 17

EMG machine, monitor, amplifier, stimulator, needle electrode, recording electrode

Question 18

Surface vs. Needle

Answer 18

Surface: disposable/nondisposable, ring or disc, all surface electrode

Needle: disposable, mono/bipolar concentric, active is needle, all other are surface

Question 19

General consideration

Answer 19

replacing electrode
alcohol/clean skin
disposing of needles in sharps container
measuring site with tape

Question 20

Precautions

Answer 20

morbidly obesed
thin individual
bleeding disorder
blood cautions

Question 21

Contraindications

Answer 21

automatic cardiac defibrillator
pacemaker
metal lining
soft tissue infection
indwelling catheter

Question 22

Variables

Answer 22

25 for room temp, 31 for UE, 29 for LE

Coldertemp: requires more current to get to AP, longer to go from rest to AP, sodium channels open slower=decreased NCV, remain open longer for increased AMP/Duration

Question 23

Age and myelination

Answer 23

complete by age 5
mild decrease by 40
sig decrease by 70

Question 24

UE vs LE nerves

Answer 24

UE: shorter latency, increased NCV, increased temperature, shorter nerves, thicker diameter

Question 25

Wave form analysis

Answer 25

measures largest, fastest fibers Evoked potentials from sensory nerve fibers. SNAP, orthodromic or antidromic Evoked potentials from muscle. Compound motor action potentials. orthodromic shape, area, rise time, duration, amp affected by axonal pathology, latency affected by demyelination, NCV affected by pathology

Question 26

Insertional activity

Answer 26

brief electrical activity with insertion crisp healthy muscles don't make a sound if needle stops moving damages the muscle when inserted, test all 4 quadrants normal muscles are crisp, 150ms decreased insertional activity atrophied muscles, needle into the sand increased insertional activity, muscle pathology, sharp positive waves that don't last, >300ms

Question 27

Examination of muscle at rest

Answer 27

abnormal spontaneous muscle activity | denervation, positive membrane caused by inc sodium

Question 28

Positive sharp waves

Answer 28

dull thud, mm ap, recorded from mm with innervation impairment, positive deflections from basline 0.5 to 15Hz

Question 29

Fibrillations

Answer 29

single muscle fibers firing autonomously rain drops hitting roof of car impair innervation regular pattern

Question 30

Complex Repetitive discharge

Answer 30

spontaneous activity stim adjacent mm motor boat misfiring >6months neurogenic/myopathic condition

Question 31

Myotomic discharge

Answer 31

prolonged fashioned AP delayed relaxation dive bombing waxing/waning chronic radiculopathies/neuropathies myotomic dystrophy polymyelitis

Question 32

Myokymic discharge

Answer 32

group of spontaneous motor potentials continuous or discontinous regular firing pattern/rhythm

Question 33

Spontaneous end plate potential

Answer 33

if needle in the endplate of health muscle, painful and spontaneous activity, must reposition

Question 34

Miniature endplate potential

Answer 34

short duration/amp, monophasic, spontaneous release of AcH

Question 35

Endplate spike

Answer 35

short duration, int amp, depolarization from a single fiber

Question 36

Motor unit amplitude

Answer 36

increases when reinnervated represents fiber density peak to peak decreases when myopathic condition

Question 37

Motor unit duration

Answer 37

increase with neuropathic decreases with myopathic initially from baseline normal is 5-15ms

Question 38

Motor unit phasic

Answer 38

``` phase is when it crosses baseline from negative to positive pole polyphasic >4 normal is <4 10-35% of normal muscle is polyphasic ```

Question 39

Recruitment how to inc force

Answer 39

increase firing rate | increase units recruited

Question 40

How to measure units/second

Answer 40

measure motor units repeated across the sweep multiply by 10 yields the MUAP/1second

Question 41

decreased recruitment

Answer 41

nerve trauma, neurogenic | increased firing rate and decreased recruitment

Question 42

Early recruitment

Answer 42

myopathic, recruits large units early with minimal force produced

Question 43

Pitfalls

Answer 43

``` bad subj/obj exam technical difficulties measuring error temperature anamolous innervation accessory peroneal nerve ```