Biofeedback Definition .
Biofeedback is an instrumentation and technique which is used to accurately measure, process and feedback some reinforcing information via auditory or visual signals by electronic or electromechanical device especially for therapeutic purposes. It can also be simply defined as the process of furnishing an individual information of his body function, so as to get some control over it. Biofeedback can be used to assess the physiological functions and then to improve it by having proper control over it.
The information regarding various physiological functions like heart rate, blood pressure, skin temperature, force generated by muscular contraction or relaxation, range of motion of joints, etc. are recorded and displayed in front of the patient. Various forms of information can be reinforced back to the patient like kinesthetic, visual, auditory, cutaneous, vestibular, etc. The patient is made to visualize the functions. The target is set at the higher or lower sides of the patients normal capacities.
The aim is to achieve the desired targets. This is not different in principle from the reeducation given by the physiotherapist in providing feedback for the correction of posture or for the initiation of muscle contraction. Information from the muscle spindles, joint position, joint range of motion, etc. all gives a source of feedback. Motor functions are thus improved and well controlled by the patient. It is also considered that feedback should be proportional to the response.
A strong contraction of muscle produces a strong signal. Also, a visual signal by a digital display is thought to be more effective than an auditory feedback as comparisons are to be made during further contractions. Since the 1960s, biofeedback has been recognized as a clinical tool in clinical medicine, behavioral medicine, physiotherapy and rehabilitation medicine. Information regarding history of biofeedback is not readily available to physiotherapists and it does not appear to be widely described or discussed.
Various references suggest that the systematic study of biofeedback started in 1960s with attempts to train voluntary control of autonomic function, such as heart rate and blood pressure. Although significant improvement may occur in different conditions, how far the biofeedback devices are effective, should be verified by repeated research in this field. In general, biofeedback can be defined as the process of furnishing an individual with information about body functioning, so as to get some voluntary control over it. This information regarding body functioning can be given to the individual via visual or auditory signal through a suitable instrument.
Types of Biofeedback .
1. Myoelectric Feedback .
2. Postural feedback .
3. Feedback Goniometers .
4. Pressure or force Biofeedback .
5. Orofacial devices .
6. Toilet training devices .
7. Stress-related devices .
8. Cardiovascular Biofeedback .
9. Electroencephalograph Biofeedback .
10. Feedback Thermometers .
11. Hemoencephalography Biofeedback .
12. Pneumograph Biofeedback .
13. Capnometer Biofeedback .
1. Myoelectric Feedback .
Myoelectric feedback is also known as EMG biofeedback and is commonly used in physiotherapy . A set of surface electrodes is placed on the skin over chosen muscle or muscle group to detect electrical signals associated with muscle contraction. These signals are amplified and translated into simple auditory and visual signals that are very easy to understand. This auditory or visual information concerning the state of muscle tension or relaxation is provided to the patient via auditory or visual display.
Auditory display is in the form of clicks or buzzing sound and visual display is in the form of movement of meter needle or glowing of the lights or computer display, rather than an oscilloscope trace. As this display bears an approximate relationship to the magnitude of the muscle contraction causing it, re-education of the muscles is possible. In other words, it is possible to get the desired response from the muscles with this device by increasing or decreasing the activity of these muscles.
Myoelectric biofeedback is commonly used in the treatment of recovering peripheral nerve injuries, writer’s cramp, blepharospasm, training specific muscle activity after tendon or muscle transplant and dystonic conditions. It is also used to improve shoulder control, to re-educate dorsiflexion of foot and to reduce spasticity of plantar flexors in hemiplegia. Biofeedback devices can also be used in the treatment of spasticity in cerebral palsy and multiple sclerosis.
2. Postural Biofeedback .
Scoliosis biofeedback device is a modified orthotic device that is beneficial in the treatment of scoliosis. Whenever, the scoliotic wearer leans against a thoracic pad of this device, he receives the auditory signals which encourages him to straighten the spine. Inclination monitor is helpful in postural control. Inclination monitor device can be worn anywhere on the trunk and senses a tilt from vertical. Head position trainer device can be used in cerebral palsy children with delayed head control. The tremor monitor device measures the hand steadiness and is used to improve hand control.
3. Feedback Goniometers .
Feedback goniometer devices monitor the joint angles. Elbow angle monitor is used to increase the range of motion of elbow joint. Knee angle monitor is useful in prevention of hyperextension at knee. Ankle angle monitors can be used in the treatment of foot drop during swing phase of the gait. Hip rotation monitor device measures internal and external rotation of the foot with respect to the pelvis and may be useful in correction of gait deviations such as, excessive internal or external rotation of hip.
4. Pressure or Force Biofeedback .
Pressure or force biofeedback devices monitor the pressure or force. The limb load monitor consists of a shoe insole with pressure sensor, which senses the amount of the weight applied to it. It is used to encourage the patients like hemiplegics to put more weight on affected leg while standing or walking. Prosthetic grip strength monitor is applied to myoelectric upper limb prosthesis for strengthening of the grip.
5. Orofacial Control Devices .
Orofacial control devices can be used in the treatment of orofacial problems in cerebral palsy children. Jaw closure monitor is helpful in drooling problem. Wet chin alarm device detects the build up of saliva and gives auditory signals to the wearer so as to control it. Palatograph detects the position of tongue on the roof of mouth.
6. Toilet Training Devices .
Toilet training biofeedback devices can improve toilet activities. The enuresis alarm detects the presence of urine and sound the alarm. It works by detecting changes in electrode conductance when moisture is present between electrodes. It is useful in the treatment of bed wetting. Perineometer is used in the re-education of pelvic floor muscles in case of incontinence. It works by measuring the pressure or electrical activity of pelvic floor muscles through vaginal or rectal pressure probes or electrodes.
7. Stress-related Devices .
Stress-related biofeedback devices minimize the stress by increasing relaxation. The EMG biofeedback device can be used in the treatment of tension headache. For this, relaxation of the occipitofrontalis muscle and posterior neck muscles is taught, since it is believed that the cause of this type of headache is tension in these muscles. The galvanic skin response monitor detects the changes in conductance of hand caused by the activity of sweat glands.
Since, the skin conductance is associated with arousal, the patient can learn to reduce arousal to achieve whole body relaxation. It may be valuable in reducing spasm in cerebral palsy in addition to inducing relaxation in normal individuals. For epileptic patients, a biofeedback device that detects the special rhythm in electroencephalograph (EEG) can be used to reduce the frequency of epileptic fits.
8. Cardiovascular Biofeedback .
In patients with hypertension, blood pressure can be monitored and displayed to them so that they gradually learn to gain some voluntary control over it. Biofeedback can also be used in the treatment of cardiac arrhythmias. Here, the heart rate is monitored and displayed to the patient who can learn to gain some voluntary control over it. In Raynaud’s disease, the temperature of the finger is monitored and the patient attempts to increase the temperature voluntarily.
9. Electroencephalograph Biofeedback .
An electroencephalograph monitors the activity of brain waves. These brain waves correspond to different mental states such as wakefulness, relaxation, calmness, light sleep and deep sleep. Hence, this biofeedback can be used for relaxation.
10. Feedback Thermometer .
A thermistor attached to the subject’s digits measures the skin temperature. Since, there is a correlation between a drop in body temperature and the patient’s experience of stress, a low temperature reading indicates the need to begin relaxation techniques. Temperature biofeedback can also help in treating certain disorders like Raynaud’s disease and migraines.
11. Hemoencephalography Biofeedback .
Hemoencephalography biofeedback is an attempt at functional infrared imaging. It measures the differences in the color of light reflected back through the scalp based on the relative amount of oxygenated and unoxygenated blood in the brain.
12. Pneumograph Biofeedback .
A pneumograph biofeedback measures abdominal or chest movement while breathing, with a strain gauge. They are used to detect breathing rate and correct altered breathing pattern.
13. Capnometer Biofeedback .
A capnometer biofeedback measures end-tidal CO2 with an infrared detector. It aims to normalize end-tidal CO2 at five percent.
General Principles of Biofeedback .
A behavioral positive reinforcement or “reward “model is usually employed with biofeedback techniques. Simply stated, when patients generate appropriate motor behaviors, they are positively reinforced. The audio and visual feedback stimuli, and other nonverbal information, are usually much faster and more accurate than the therapist’s comments.
Unlike other interventions, the benefits of accomplishing small changes in motor behavior in the desired direction can be reinforced, which should speed the rehabilitation process. In behavioral learning terminology, the therapist uses the biofeedback signal to shape the motor behavior by reinforcing the patient’s successive approximations to the goal behavior or functional outcome. When the patient succeeds in controlling the signal, the therapist must relate it to the underlying motor behavior and then reestablish the expected outcomes.
Reinforcing already-learned behaviors is of course, futile, so the machine’s threshold should be monitored frequently, increasing the task’s difficulty as motor skills progress. Feedback can be intrinsic or extrinsic. Intrinsic feedback is the body’s internal feedback mechanism, which uses visual, auditory, vestibular and proprioceptive mechanisms. Extrinsic feedback is any feedback derived from an external source (e.g. a biofeedback signal or physical therapists comments) that augments intrinsic feedback.
Biofeedback in Rehabilitation .
When using biofeedback, the patient must :
1. Understand the relationship of the electronic signal with the desired functional task .
2. Practice controlling the biofeedback signals .
3. Perform the functional task until it is mastered and the patient no longer needs the biofeedback.
Conventional neuromuscular reeducation is based heavily on providing patients with helpful comments (feedback) to assist their recovery of previously acquired skills. The therapist’s job is to focus the patient’s attention on the underlying motor programs and biomechanical schema required to recoup those skills.
Recent applications of biofeedback have been directed at muscle imbalances and the fine tuning of motor control. The focus, for example, with the quadriceps, might be a balanced vastus medialis oblique : vastus lateralis (VMO:VL) ratio and not merely gross strength. Biofeedback is simply one technique that therapists may employ to help convey their message about motor programs and biomechanical schemata to the patient.
Biofeedback can assist the rehabilitation process by :
1. Providing a clear treatment outcome or goal for the patient to achieve.
2. Permitting the therapist and patient to experiment with various strategies (processes) that generate motor patterns to achieve the desired outcome or goal.
3. Reinforcement for getting the appropriate motor behavior.
4. Providing a process which gives orientation, time and accurate knowledge of results for the patient’s efforts.
The machine should be set to give auditory or visual feedback that corresponds to the desired motor behavior. For example, if spastic antagonist are to be monitored, the patient should be instructed to decrease the EMG activity; the biofeedback device is set to flash a light in order to provide signal of this outcome.
Alternatively, an electrogoniometer can be used which changes the pitch of a buzzer as the joint is moved in the appropriate direction. In brief, biofeedback techniques are used to augment the patient’s sensory feedback mechanism through specific and precise information about the body physiologic processes that might otherwise be inaccessible.
Indications f0r Biofeedback .
Biofeedback is a therapeutic technique that involves using electronic monitoring to provide individuals with real-time information about physiological processes occurring in their bodies. The goal of biofeedback is to help individuals gain voluntary control over these processes, with the aim of improving physical and mental health. Here are some indications for biofeedback:
1. Stress Management .
Biofeedback can be used to measure and control physiological responses associated with stress such as muscle tension, heart rate, and skin temperature. Learning to control these responses can help individuals manage stress more effectively.
2. Muscle Relaxation .
Biofeedback is often used to help individuals learn to relax specific muscle groups. This can be beneficial for conditions such as tension headaches, migraines, and certain types of chronic pain.
3. Anxiety and Panic Disorders .
Biofeedback can assist in managing anxiety and panic disorders by training individuals to control their physiological responses, including heart rate and breathing patterns.
4. Chronic Pain .
Biofeedback is used as part of pain management strategies, helping individuals reduce pain by gaining control over physiological processes like muscle tension and blood flow.
5. Migraines and Headaches .
Biofeedback is recognized as a non-pharmacological approach for managing migraines and tension-type headaches. It focuses on reducing muscle tension and promoting relaxation.
6. Hypertension (High Blood Pressure) .
Biofeedback has been employed to help individuals lower blood pressure by providing real-time feedback on heart rate and blood pressure, allowing them to learn relaxation techniques.
7. Attention Disorders .
In some cases, biofeedback is used as a complementary approach for attention disorders, such as attention-deficit/hyperactivity disorder (ADHD), to enhance focus and concentration.
8. Sleep Disorders .
Biofeedback can be applied to manage sleep-related issues, such as insomnia. Training individuals to control physiological parameters like muscle tension and heart rate can promote relaxation and improve sleep quality.
9. Raynaud’s Disease .
Biofeedback may be used to help individuals with Raynaud’s disease, a condition that affects blood flow to certain parts of the body, usually the fingers and toes, in response to cold or stress.
10. Urinary Incontinence .
Biofeedback is sometimes used as part of pelvic floor muscle training to help individuals gain control over pelvic muscles, which can be beneficial for conditions like urinary incontinence.
Contraindications of Biofeedback .
Biofeedback is generally considered safe and non-invasive, there are certain contraindications and precautions that individuals and healthcare providers should be aware of before implementing biofeedback therapy. It’s essential to consult with a qualified healthcare professional to assess the suitability of biofeedback for a specific individual and condition. Some contraindications and considerations include:
1. Psychiatric Disorders .
Individuals with certain severe psychiatric disorders, such as schizophrenia or severe personality disorders, may not be suitable candidates for biofeedback. In some cases, it could potentially exacerbate symptoms or be challenging for individuals to engage in the necessary self-regulation.
2. Cognitive Impairment .
Individuals with severe cognitive impairment or intellectual disabilities may find it difficult to understand and engage in the biofeedback process effectively.
3. Medical Instability .
Biofeedback may not be appropriate for individuals with certain unstable medical conditions. For example, individuals with unstable cardiovascular conditions or uncontrolled epilepsy may need careful monitoring and consideration before undergoing biofeedback.
4. Severe Chronic Pain .
In cases of severe chronic pain, caution is advised. Individuals experiencing intense pain may find it challenging to focus on the biofeedback process, and the therapy may need to be adapted to their individual needs.
5. Acute Medical Conditions .
Individuals experiencing acute medical conditions or crises may not be suitable for immediate biofeedback intervention. In such cases, stabilization of the medical condition is a priority before introducing biofeedback.
6. Skin Conditions .
Certain skin conditions, such as open wounds or infections in areas where sensors are applied, may be a contraindication to using biofeedback equipment in those specific areas.
7. Seizure Disorders .
While biofeedback is generally considered safe for individuals with epilepsy, caution is advised. Individuals with seizure disorders should be monitored, and biofeedback parameters should be adjusted to minimize the risk of triggering seizures.
8. Pregnancy .
Biofeedback involving abdominal sensors may need to be modified or avoided during pregnancy, especially in the later stages, to prevent discomfort or potential risks.
9. Inability to Provide Informed Consent .
Individuals who are unable to understand or provide informed consent for biofeedback therapy may not be suitable candidates. This includes individuals with cognitive impairment or those who are unable to actively participate in the therapeutic process.
Use of EMG Biofeedback for Neuromuscular Reeducation .
Electromyogram (EMG) biofeedback is useful for neuromuscular reeducation. The basic EMG device comprises of one ground and two surface electrodes, an amplifier, an audio speaker and a video display. A surface EMG for skeletal muscle activity can be compared with electrocardiography (ECG) being done for heart. The EMG signal is transmitted from the muscle through the skin, through the electrode paste, through the electrodes, through the wires and then to the amplifier.
The equipment is quite complex and for skilled use a good understanding of the EMG signal’s characteristics is required. The EMG display bears an approximate relationship to the magnitude of the muscle contraction which causes it. The relationship is quite complicated because the motor unit action potential that occurs cannot all be equally detected and recorded. However, for biofeedback purposes the overall effect of stronger contractions leads to louder clicks and a large display on the screen are adequate.
Uses of Biofeedback .
1. Peripheral nerve injuries .
Biofeedback can be used in the treatment of recovering peripheral injuries. Once a motor unit activity has been detected on electromyography, voluntary repetition can be encouraged. Electromyogram (EMG) biofeedback provides a means of extending the recognition of least possible motor activity and then quantifying it to some extent. In cases of nerve transplant or tendon transplant biofeedback can be useful to provide assistance to the patient to learn the new muscle action.
2. Spinal cord injury .
Biofeedback techniques have been recommended and applied in the rehabilitation of spinal cord injury patients. Feedback is provided to the patient to perform voluntary action in paralyzed muscle. After several repetitions gradual positive response can be seen.
3. Hemiplegia .
Several studies have found biofeedback to be useful method of treatment in hemiplegia. Biofeedback is commonly used into reeducate controlled dorsiflexion of foot and thus to improve gait. It can also be used for deltoid in order to improve shoulder control.
4. Dystonic conditions .
Dystonic conditions in which the patient suffers uncontrollable movements and postures can also be treated with EMG biofeedback. Spasmodic torticollis is one such condition in which voluntary muscle contractions are used to inhibit inappropriate neck movements.
5. Treating spasticity .
Several spastic conditions such as cerebral palsy, multiple sclerosis, head injury, etc. can be treated with biofeedback in order to reduce and control spasticity. It should be noted that in all neurological disorders treated by biofeedback, it is assumed that there are some intact neuronal pathways available to suppress spasticity.
6. Postural control .
Biofeedback devices are used to have appropriate postural control. A trunk inclination monitor which signal tilt can be used for the treatment of low backache. A tilt away from normal can provide an audio-feedback and thus helps correcting posture.
7. Muscle strengthening .
Muscle strength training devices have an electronic display which indicates the strength in a muscle and acts as a biofeedback to the exercising muscles. It provides a feedback by display of force produced by the contracting muscle and thus helps to strength the muscle further.
8. Functional reeducation .
Biofeedback can be effectively used in improving functional reeducation. The biofeedback devices can be used in various ways to encourage repeated practice of a particular movement to improve function.
9. Providing relaxation .
The electrical resistance of hand or fingers are measured and displayed. Increase or decrease in stress is reflected in the amount of sweating that occurs which in turn determines the skin resistance. Biofeedback devices are used effectively for providing general relaxation to the body. Pulse rate or respiratory rate is recorded by some apparatus and findings are displayed to the patient. The patient tries to control and regulate the pulse and respiratory rate and thus inducing relaxation.
Limitations of Biofeedback .
The biofeedback must be relevant, accurate and rapid to enhance motor learning. If any of these three elements is missing, the traditional form of feedback, i.e. verbal feedback can be used which is more convenient.
1. Relevancy .
Useful relevant information is important for the desired motor response. It should neither be too short or too long. Electromyogram (EMG) biofeedback can provide relevant information about the motor unit activity which cannot be available otherwise.
2. Accuracy .
The biofeedback device and the way, it is used, should provide an accurate information. Many believe that the EMG signals are not sufficient to constitute true process of feedback. They use specific devices that directly measure force or joint range of motion. For obtaining accurate results, appropriate biofeedback device and proper technique of application should be used.
3. Rapid information .
All EMG processes delay electrical events during signal amplification and conversion to audio speaker and visual meter because of inherent delays from the electrical circuits. Most commercial EMG biofeedback instruments gives 50 to 100 millisecond delay before the signal reaches to the ears and eyes of the patients.
Biofeedback to be useful must provide immediate rapid information. While biofeedback is employed, the movements are necessarily closed loop. In brief, the information used to be feedback to patients must be accurate, relevant and rapid for effective therapeutic use. Therapists must choose the appropriate instrument or device that provides the most meaningful information to the patients.
Treatment Duration .
There are no specific criteria for the duration of the treatment with biofeedback devices. However, favorable results are likely to occur with the use of the biofeedback devices for 10 to 30 minutes per day.
Advantages of Biofeedback .
Biofeedback provides corrective information to the patient immediately. The patient gets involved actively in his own treatment. Biofeedback may not require sophisticated understanding of skills by the patients. Biofeedback devices can be used during on-going activities. It may save physiotherapist’s time.
Disadvantages of Biofeedback .
Biofeedback treat symptoms and not the underlying cause of symptoms. Biofeedback training or treatment is uneconomical as all of these devices are not available commercially at all places. Biofeedback devices are unacceptable to patients who do not like to put on wires and electronic boxes over their body. Sometimes, physiotherapists may need special training for the use of biofeedback. Biofeedback could be just a form of training rather than treatment.
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