© 2004 Electromyographic Biofeedback Chapter 18

© 2004 Purpose To measure, process, and feedback biophysical information Biofeedback does not monitor the actual response itself It monitors conditions associated with the response

© 2004 Types of Biofeedback Units Electromyographic Measures electrical activity in skeletal muscle Measures electrical activity in skeletal muscle Peripheral Temperature Measures temperature changes in distal extremities Measures temperature changes in distal extremities Increased temperature indicates a relaxed state Increased temperature indicates a relaxed state Decreased temperature indicates stress, fear, or anxiety Decreased temperature indicates stress, fear, or anxietyPhotophlethysmography 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 EMG Detects the amount of electrical activity associated with a muscle contraction converts it to visual and/or auditory feedback converts it to visual and/or auditory feedback promotes strength of the muscular contraction or facilitates relaxation promotes strength of the muscular contraction or facilitates relaxation Can be used to create a game-like, competitive atmosphere to motivate rehabilitation

© 2004 Biophysical Processes and Electrical Integration EMG biofeedback measurements vary between brands Electrical activity within the muscle increases as more motor units are recruited These signals are picked up by electrodes, amplified, and converted into visual or auditory signals Electrode placement, superficial vs. deep muscles, electromagnetic noise, and tissue variability cause variability in the signals produced

© 2004 Electrodes Basic units have one channel composed of three surface electrodes on a self- adhesive electrode “Active” Electrodes Detect electrical signal “Reference” Electrode Filters nonmeaningful information

© 2004 The Process Identify Signal Get the eletromyographic signal from the body Amplify Signal Filter out background noise Similar to a volume control on a radio, enhance the strength of the signal to meaningful levels Rectify Signal Make all values “positive” Integrate Signal Group the data into meaningful clusters

© 2004 Indications Facilitate muscle contractions Regain neuromuscular control Decrease muscle spasm Promote relaxation

© 2004 Effects Purpose: reestablish sensory-motor loops ‘forgotten’ by patient Used to facilitate increased or decreased levels of motor unit activation Sound/visual cues stimulate brain along with watching the muscle contract assists in reopening a neural loop

© 2004 Neuromuscular Effects The cognitive process attempts to inhibit pathways for relaxation The goal is to decrease the number of motor impulses being relayed to the muscle in spasm

© 2004 Pain Reduction Purpose: restore normal function of the body part Facilitating reduction of muscle spasm reduces the amount of mechanical pressure placed on nociceptors

© 2004 Contraindications General Rule: If the patient is prohibited from moving the joint or isometric contractions, then EMG should NOT be used Unhealed tendon grafts Avulsed tendons Third degree tears of muscle fibers Unstable fracture Injury to joint structure, ligaments, capsule, or articulating surface

© 2004 Clinical Application Biofeedback units vary greatly Consult the user’s manual for specific instructions