Surface EMG and Biofeedback Flashcards
Clinical Electromyography
used to evaluate the scope of neuromuscular disease or trauma…as well as assist with establishing anticipated goals and expected outcomes
Types of EMG
nerve conduction velocity
electromyography
Kinesiological Electromyography
used to study muscle activity and establish the role of various muscles in specific activities
How is kinesiological primarily carried out?
Electromyography (primarily surface EMG
sEMG
can also be used as a kinesiological tool to examine muscle function during specific, purposeful tasks or therapeutic regimens
Biofeedback:
describe the use of instrumentation to make covert physiological processes more apparent to the patient.
Motor unit:
LMN and all muscle fibers it connects to
MUAP
motor unit AP
the electrical activity that comes with the depolarization of a single motor unit
CMUAP:
Combined Motor unit AP: the net (sum) of all depolarization (electrical activity) that comes when a patient voluntarily contracts a muscle to move
3 phases to any instrumentation that is used to sense and record any electrical activity of muscle:
Input phase
Processing phase
Display (feedback phase)
Best and most widely used electrodes?
silver-silver chloride
Kinds of electrodes:
reusable/permanent
single use/disposable
Permanent:
do not need gel: placed on clean skin and taped on
Single use
pre-gelled, self-adhesive
Recording electrodes:
2/3 electrodes are recording “active: ones that sense electrical activity
Isolation ground/reference
make sure that 2 active electrodes are picking up activity from patient
Why do we use 2 active electrodes?
The machine compared the polarity of 2 electrodes.
Location of active electrodes?
generally placed at the midpoint of the muscle being recorded in line with the muscle fibers
Electrode location placement consideration:
Place electrodes “in position of movement (squat)
Consider how skin may “shift” over the underlying muscle during movement
What does spacing effect?
how much of muscle you sample electricity from
Volume Conduction
salt water conducts electricity through its volume to surface of the skin
Cross talk
if electrodes placed far apart; salt water can conduct electricity from other muscle groups and the electrodes can pick it up
Artifact:
An “excess” or “erroneous” signal that is detected and displayed but does not come from the electrical activity of motor neurons or muscle tissue
Movement artifact:
cables of machine do not move too much: can cause electrical display to shift
physical movement, not electrical activity
Power line interference:
isolation ground not eliminating interference and it shows in recording
ECG:
might see PQRS complex if recording near heart
Filtering:
the electrical signal from the patient is filtered to only allow frequency components of 80-250 Hertz to pass.
Low smoothing:
screen display changes very quickly to follow changes in muscle activity
High smoothing:
screen display does not change quickly to follow changes in muscle activity
trend over time
Amplification:
Can be used to adjust the “size” of an EMG signal on a given display.
Goal/Threshold:
Some level of EMG that a patient can be prompted to “contract up to” or “relax down to
Display Modes:
continuous
work/rest
Continuous Display:
The unit continuously displays the patient’s electrical activity along with any goals or other feedback
Work/Rest Mode:
The unit prompts the patient to contract toward the goal for a specific period of time and then prompts the patient to relax for a specific period of time
Types of audio feedback:
tone (changing pitch or volume)
clicks (changing frequency or volume)
Audio tones can be:
continuous
on above goal
on or off below goal
Video feedback to patient:
Moving trace on computer screen
Bar graphs
Banks of LEDs
Concurrent Assessment of Muscular Activity (CAMA)
the output of the sEMG unit is directed to the patient, who is asked to respond appropriately and modify his or her performance
EMG-triggered NMES
CMUAP monitored and threshold is set above what patient can do. Patient contracts target muscle. When threshold is met NMES stimulates a more powerful contraction
