volitional potentials

Question 1

exp Electromyographic (EMG) Biofeedback

Answer 1

Monitoring, detection, or assessment of skeletal muscle activity - to know if inc (hypotonic) or dec (hypertonic)

Question 2

what does EMG detect

Answer 2

no current delivered kc voluntary contraction - records upon contraction of muscle

Question 3

exp facilitatory biofeedback

Answer 3

inc muscle activity (post-injury or post-operatively) - hypotonic or flaccid

Normalize muscle functions

Improve volitional motor control following CNS dysfunction

Question 4

exp inhibitory biofeedback

Answer 4

dec muscle activity (spasticity in CNS dysfunctions)

dec muscle activity (due to postural stress)

dec muscle activity/guarding (due to chronic pain)

Question 5

instrument used for EMG biofeedback

Answer 5

electromyograph

Question 6

discuss recording electrode placement

Answer 6

over muscle to be recorded - proper spacing and avoid crosstalk

Question 7

discuss ground electrode placement

Answer 7

over bony surface to minimize extraneous electrical activity or nosie

Question 8

compare surface EMG and needle EMG

Answer 8

sEMG - non invasive; superficial

nEMG - invasive; deep

Question 9

uses of biofeedback

Answer 9

training technique to gain voluntary control over muscular or autonomic nervous system functions using auditory or visual stimuli

Question 10

purpose of signal amplification and filtration

Answer 10

maximize signal-noise ratio and minimize distortion

Question 11

noise sources during EMG

Answer 11

noise of electrical parts in machine

ambient noise

motion artefacts bet electrode and skin

inherent instab of EMG signal d/t random firing of motor units

Question 12

compare high and low pass filter

Answer 12

high - allows high freq; 5 Hz/10-20 Hz cut-off

low - allows low freq; 500 Hz cut-off

Question 13

what is linear envelop

Answer 13

rectification + low pass filter

Question 14

what is butterworth or chebyshev

Answer 14

traditional low-pass filter of rectified signal

Question 15

what is Movag

Answer 15

certain amount of data are averaged using the
sliding window technique

Question 16

what is RMS

Answer 16

preferred method

based on square root calculation - reflects mean power of signal

Question 17

normal muscle fatigue index of EMG at rest

Answer 17

(+) insertion activity

miniature endplate action
potentials

no muscle action potentials

Question 18

abnormal muscle fatigue index of EMG at rest

Answer 18

(+) fibrillations / fasciculations

complex discharges

inc or dec insertional activity

Question 19

normal muscle fatigue index of EMG at mild contraction

Answer 19

biphasic or triphasic muscle AP

motor unit potentials (MUP) from small amplitude potentials → progressively large amplitude potentials

Question 20

abnormal muscle fatigue index of EMG at mild contraction

Answer 20

polyphasic amplitude tas either increase or decrease

altered recruitment patterns

Question 21

normal muscle fatigue index of EMG at max contraction

Answer 21

inc frequency

(N) stepwise - inc interference patterns

Question 22

abnormal muscle fatigue index of EMG at max contraction

Answer 22

dec interference pattern - hypo

early full interference pattern - hyper

Question 23

guidelines for all electrophysiologic testing

Answer 23

Patient should be comfortable

Ensure correct electrode placement

Secure electrodes properly

Perform first a detailed physical examination of
strength, sensation, coordination, reflexes and
other neuromuscular function

Use latex gloves, goggles and gown for needle
EMG

When applying electrical stimulation, check for
contraindications and precautions