Copy of Biofeedback

Biofeedback is a technique that teaches individuals how to control physiological processes by providing real-time feedback on bodily functions such as heart rate, muscle tension, and skin temperature. This method is often used to help manage stress, anxiety, and chronic pain.

It provides the patient the chance to make appropriate small changes in performance that are immediately noted and rewarded so that eventually larger changes or improvements in performance can be achieved

study and measure the motor unit action potential (MUAP) that are generated by active muscles and are converted into audiovisual signals that are used to reinforce voluntary control. Principles of electromyographic signals: functional unit of motor unit consists the anterior horn cell, peripheral nerve, neuromuscular junction, and the muscles that the nerve innervates§ after the impulse has activated the motor end plate via the peripheral nerve, depolarization spreads out in all direction over the muscle fibers and is being measured and the electrodes can pick the potential difference which is the motor unit action potential positive and negative impulses picked by the electrodes and amplified by a differential amplifier (cancels out or rejects any components that the 2 signals have in common coming from the active electrodes and ground
electrical activity from the muscle is then further rectified (the deflection of the negative phase will be flipped upward toward the positive phase) RECTIFICATION signal is then smoothen (wherein it eliminate the peaks and valleys or eliminating the high frequency fluctuations that are produced with charging electrical signal) FILTERING after which it undergoes INTEGRATION (forms the basis for quantification of electromyographic (EMG) activity which is displayed thru visual or auditory signals EMG activity is usually expressed in terms of microvolts ARTIFACTS-are unwanted signals that can increased the MUAP signals from the motor unit.

SOURCES OF ARTIFACTSv Volume conducted artifacts – result from signals from other nearbymuscles; solution is place the active electrodes closer to one anotherv Movement artifacts – whenever movement occurs such as movementof the skin, cables, electrodes; solution is remove the cable or havehigh CMRRv Power line interference – interference caused by other equipment thatare plug at the same outlet; solution is to plug other machine to theother outletv Other PT machines and appliances; solution is to place the machinesand appliances farther away from biofeedback machinev Cardiac pacemaker

Machine FeaturesCommon Mode Rejection Ratio (CMRR)- ratio between the desired signal voltage to the unwanted signals (e.g. 1,000 : 1); if CMRR is high, it can eliminate artifacts (from lights, equipments and other appliances)Frequency response (Bandwidth)- the difference between the lowest and highest frequency response ofthe device; greater bandwidth can easily detect MUAP but can also detectmore artifactsNoise Level- the voltage that the device can recognize (e.g. 5 microvolts – less thanthe value, can’t be recognize); the lower the noise level, the moresensitive is the device but also more artifacts will be notedGain – refers to the sensitivity of the device to amplify the signals; greaterthe gain, will make a smaller signal larger on the display

Factors that can influence electrical activity recorded by electrodes:§ Distance of the electrodes from the structure – farther is the electrode, lesssignal is recorded§ Number and size of the fibers in the motor unit – a larger motor unit will producemore muscle activity§ Distance between the muscle fibers – if muscle fibers are spread out, lessmuscle activity will be noted§ Size of electrodes – the greater the size of electrodes, the more it can detectmuscle activity but more artifacts will be encountered§ Distance between electrodes – with increased distance, the more it can detectmuscle activity but more artifacts will be encountered

Purposes of applying biofeedback to the patients• For patient to improve its motor system; to improve muscle performance by facilitating motor learning• For therapist to evaluate patient’s motor systemImproving motor system of patient has 2 goals:• Reducing the myo-electric activity of muscle for spastic and hypertonusmuscle• Increasing the myo-electric activity of muscle for flaccid and hypotonusmuscleTherapeutic effects of biofeedback:• Patient will be aware of the activity of the muscle and will be able tomanipulate such activities• Patient will be encourage to perform such activities if noting there areactivities of the muscles

INDICATIONS• Muscle paralysis (flaccid or spastic)• Muscle tendon transfer• Hemiplegia• Pain due to muscle spasm• Peripheral nerve injury• Bell’s palsy• Upper and lower motor neuron lesion• Torticollis• Immobilization• Joint repair

CONTRAINDICATIONS§ Unreliable patients§ Patient that is both blind and deaf§ Dermatological conditions§ Cardiac pacemaker if it can interfere with the biofeedback device Criteria for patient selection for biofeedback training:§ Patient should have good vision, hearing and communication abilities§ Patient should have a good comprehension of simple commands andconcentration§ Patient should have no profound proprioceptive sensory loss

ELECTRODESo Active or recording electrodes- electrodes that record or note the motor unit action potential; exist inpairs- 2 types:- surface electrodes – electrodes that are placed at the surface of the skin; no discomfort on the part of the patient, easy to apply. Disadvantages are that it can detect mostly superficial muscles and more than one muscle group; types of surface electrodes : metal electrodes, adhesive electrodes, carbonized rubber electrodes- needle electrodes – electrodes that penetrates intramuscularly; can detect deeper muscle activity, specific muscle activities are noted Disadvantages are difficult to apply, more discomfort on the part of the patient; these electrodes are only used by physicians

electrodes should be made up of material that easily detects muscle activity (gold, silver)- electrodes ideally should be smaller in size (typically 3-5 mm.) so as to minimize artifacts- electrodes should be applied closer to each other to minimize artifactso Ground or reference electrode - is applied to provide a mechanism for cancelling out the interference effect of external electrical noise such as that caused fluorescent lights, electrical apparatus and other machines- is attached to any part of the body of the patient to ensure accurate readings of the biofeedback signal. Ground electrodes should be placed on a bony prominence to enhance signal quality and reduce noise interference.

DOSAGEq Depend on the goals of therapist:q For flaccid or weak muscles, the goal is to increase the muscle activityq For spastic or tensed muscles, the goal is to decrease the muscle activityq Normal unaffected side is used as reference to achieve the goal if unilateralaffectationq Starts with simple to a more complex/functional movements as patient gains motorcontrolDURATION : 5 – 30 minutes or when patient is fatigue already