emg biofeedback
DESCRIPTION
for physiotherapy under graduate studentsTRANSCRIPT
EMG-bio feed back
An electromyography – is a clinical technique that involves recording of the electrical activity generated in a muscle (muscle AP) for diagnostic purposes
An electromyogram - is a graphic representation of those electrical currents associated with muscle action
It is a method of controlling a system by reinserting into it the results of its past performance.
-wiener1948
‘A technique which enables the individual to readily determine the activity levels of a particular physiological process, and with appropriate training, learn to manipulate the same process by an internalized mechanism.’
“Operant conditioning learning”
Positive feed backNegative feed back
Electromyographic Measures electrical
activity in skeletal muscle
Peripheral Temperature Measures temperature
changes in distal extremities
Increased temperature indicates a relaxed state
Decreased temperature indicates stress, fear, or anxiety
Photophlethysmography Measures the amount of
light reflected by subcutaneous tissue based on the amount of blood flow
Galvanic skin response Measures electrical
resistance in the skin Moist skin conducts a
current better than dry skin
© 2004
Chance to make appropriate small changes in performance
Eventually larger changes or improvements in performance can be accomplished
The goal is to train the patient to perceive these changes without the use of the measuring instrument so that he or she can practice independently
ADVANTAGES
Biofeedback instruments may use the following signals/devices/sources
Eg: Temperature- Temperature- thermometer-skinthermometer-skin
Type What's Measured Basic method Used For
Brain waveEEG Electrical activity in the brain
Sensors placed on scalp
Alcohol and drug addition, brain damage, epilepsy, hyperactivity, insomnia
Breathing Breath rate, rhythm, volume, and location
Sensors around chest and abdomen or around mouth and nose
Anxiety, asthma, hyperventilation
Electro dermal response
Sweat gland activity Sensors placed on the muscle group in question
Anxiety, overactive sweat glands
Electro-myography
Muscle spasms and tension
May help treat rheumatoid arthritis, premenstrual syndrome, menstrual cramps, and menopausal symptoms
Incontinence, muscle pain, physical rehabilitation, stress, teeth grinding (TMJ), tension headaches, torticollis ("wry neck")
Finger Pulse Pulse rate and amount of blood in each pulse (the higher these are, the more wired your autonomic nervous system is)
Sensor attached to a finger
Anxiety, irregular heartbeat, hypertension
Skin temperature (also called thermal biofeedback)
Blood flow changes (the more blood flows, the warmer the skin)
Temperature sensor (thermistor) taped to finger
Anxiety, hypertension, migraines, Raynaud's disease
1.Providing feed backAppropriateProportionalSensitivity and specificity of
equipmentAppropriate methodTime/scheduled feed back
2.User control Over the method
3.Proper starting position4.Shaping behaviorAvoid fatigue Initial success Set upper and lower threshold Change goals
It is a therapeutic procedure that uses electronic or electromechanical instruments to accurately measure, process, and feed back reinforcing information via auditory or visual signals.
In clinical practice, it is used to help the patient develop greater voluntary control in terms of either neuromuscular relaxation or muscle reeducation following injury.
© 2004
Identify SignalIdentify SignalGet the eletromyographic signal from the Get the eletromyographic signal from the bodybody
Amplify SignalAmplify SignalFilter out background noiseFilter out background noiseSimilar to a volume control on a radio, Similar to a volume control on a radio, enhance the strength of the signal to enhance the strength of the signal to meaningful levelsmeaningful levels
Rectify SignalRectify SignalMake all values “positive”Make all values “positive”
Integrate SignalIntegrate SignalGroup the data into meaningful Group the data into meaningful clustersclusters
Muscle reeducationRegaining neuromuscular control Increasing isometric and isotonic
strength of a muscleRelaxation of muscle spasmDecreasing muscle guardingPain reductionPsychologic relaxation
Measuring muscle activitySeparation / filterationElectrodesDisplaying the feedback
Biofeedback Measures electrical activity of muscle, not muscle contraction.
Gives information about the quality of a muscle contraction
Does not measure the strength of that muscle contraction specifically.
Basic units have one channel composed of three surface electrodes on a self-adhesive electrode
© 2004
“Active” Electrodes Detect electrical signal
“Reference” Electrode Filters nonmeaningful information
electrical energy received through an electrode
separated or filtered from other extraneous electrical activity on
the skin
amplifies the electrical energy
then converted to information that has meaning to the user
• Noise must be eliminated• Noise – by power lines , motor , lights ,
appliances.• Accomplished by using 2 active electrodes and a
single ground/reference electrode differential amplifier CMRR-common mode rejection ratio
• Filters are also used• Use :
Mask true electrical activity Decrease the reliability of the information being
generated
After filtering, signal indicates true muscle activity – “raw” activity
Raw activity – alternating voltageBiofeedback measures the overall
increase and decrease in electrical activity
To obtain this rectification is doneRectified signal can smoothed and
integrated
Skin preparation Application of electrodes Selection of output modes Selection of sensitivity settings Comfortable positioning of the patient Begin with easy task Teach the patient how to use the unit Brief explanation Demonstration
Skin preparation Reduce skin impedance
Positioning of electrodes Placed as near to the muscle being
monitored to minimize noise Parallel to the muscle fibers
Spacing between electrodes More the distance between the electrodes –
will include signal from nearby muscles Types
Surface electrodes Needle electrodes
Made of stainless steel or nickel plated brass kept in a plastic holder
Size : 4mm in diameter – small muscle activity
12.5mm –for large muscle groups
Increase in size will not increase the amplitude of the signal
Conducting gel/paste/cream with high salt content is used
Can be disposable and non-disposable
MONOPOLAR NEEDLE
CONCENTRIC NEEDLE
BIPOLAR CONCENTRIC NEEDLE
Visual feedbackAudio feedback
▪Line travelling across a monitor
▪Light/series of light that goes on and off
▪Bar graph▪ Incorporated video games
▪Tone▪Buzzing▪Beeping▪Clicking
An Increase increased electrical activity used to strengthen muscle contractions
Decrease decreased electrical activity used for relaxation
Goal is to reestablish neuromuscular control
Used to regain normal agonist/antagonist muscle action
For postural control retrainingUseful in patients who perform
poorly on manual muscle testsBalance/mobility
Muscle guarding Muscle guarding different from muscle
spasticity Goal : to induce relaxation or to
modulate pain by reducing electrical activity
Patient attempts to reduce visual/auditory feedback to zero
Positioning is important Verbal cues should be given to
enhance relaxation
Purpose : reduce/modulate painBreaking “pain-guarding-pain” cycleReduces pain in headaches and low
back painTechniques of imagery and
progressive relaxation is used
HemiplegiaStrokeSpinal cord injurySpasticityCerebral palsyFacial paralysisUrinary and fecal incontinence
HTNStress Reynaud's diseaseRespiratory control
severe psychosisdepressionpsychopathic personalities diabetics and others with endocrine
disordersAny musculoskeletal condition in
which a muscular contraction might exaggerate that condition