Biofeedback

Original Editor - Professor Tim Watson Top Contributors - Rachael Lowe, Ellen De Boitselier, Denys Nahornyi, Simisola Ajeyalemi, Aminat Abolade, Kim Jackson, Claire Knott, Pooja Shevale, Naomi O'Reilly, Milan Matejak, Candace Goh, Angeliki Chorti and Admin

Definition

Biofeedback therapy is an instrument-based learning process that is based on “operant conditioning” techniques. It is an evidence-based approach to improve the ability to modify involuntary processes consciously. The basic biofeedback paradigm suggests that whenever we provide a human being with feedback about a biological process, that feedback enables the individual to increase awareness of the process and gain conscious control. The governing principle is that any behaviour-be it a complex manoeuvre such as eating or a simple task such as muscle contraction-when reinforced its likelihood of being repeated and perfected increases several fold.

Physiotherapists use biofeedback to help refine a movement sequence or activation pattern to assist patients to achieve a goal. This technique involves using visual, physical and/or auditory feedback to guide the patient to give their optimal performance. The ultimate purpose is that the patient gets to know his own body signs and that he can control them consciously in the first place using biofeedback equipment, afterwards even without.

Biofeedback usually involves the measurement of a target biomedical variable and relaying it to the user using one of two strategies;

1. Direct feedback regarding the measured variable, as in the case of heart rate or heart rate variability, where a numerical value is displayed on a wearable device, such as a watch.

2. Transformed feedback regarding the measured variable, where the measurements are used to control an adaptive auditory signal, visual display or tactile feedback method.

Categories of biofeedback used in physical rehabilitation

The biofeedback measurements which are frequently used in physical rehabilitation can be categorised as being either physiological or bio-mechanical based on the parameter of interest. The physiological systems of the body which can be measured to provide biofeedback are the neuromuscular system, the respiratory system and the cardiovascular system, while bio-mechanical biofeedback involves measurements of movement, postural control and force.

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Indications

Clinicians can incorporate biofeedback techniques into the overall treatment plan for a wide variety of conditions. It is frequently used to manage stress and anxiety, either if they are the primary illness or due to another cause. There is specific evidence that exists to support the use of biofeedback for specific ailments, including the following;

• Constipation
• Fecal incontinence
• Urinary incontinence
• Chronic pain - includes chronic low back pain, chronic pelvic pain, and other pain syndromes
• Chronic insomnia
• Migraine headaches
• Chronic fatigue
• Fibromyalgia
• Epilepsy
• Motion sickness
• Depression
• Anxiety
• Raynaud phenomenon

Other indications for biofeedback are:

• CVA
• CVS/Fibromyalgia
• Chronic pain
• Neck pain
• Post-traumatic stress syndrome
• Hypertension
• Headache – migraine – tension headache
• Balance disorders
• Attention Deficit Hyperactivity Disorder
• Epilepsy

Different types of biofeedback

Many different forms of biofeedback are currently used in the clinical setting including:

• Electromyography (EMG) - measures muscle tension
• Thermal biofeedback - measures skin temperature
• Neurofeedback/ electroencephalography (EEG) - measures brain wave activity
• Electrodermography (EDG) - measures skin electrical activity
• Heat Flux - measures the rate at which heat is being dissipated from the body
• Pneumography - measures abdominal/chest movement when breathing
• Capnometry - measures end-tidal carbon dioxide
• Hemoencephalography - measures the differences in the colour of light reflected back through the scalp based on the relative amount of oxygenated and unoxygenated blood in the brain
• Photoplethysmography (PPG) - measures peripheral blood flow, heart rate, and heart rate variability

The limitations to biofeedback applications lay largely with the therapist. Given a solid understanding of the basic principles of the therapy in combination with a clinical understanding of the patient's problem, there are many novel applications for the therapy.

This page will focus exclusively on EMG Biofeedback.

Mechanism of Action

The autonomic nervous system regulates the functioning of the organs and functions of the body like breathing and beating of the heart. It isn’t dominated by our will, but it reacts to our mood. There are two major components of the autonomic nervous system, the sympathetic and the parasympathetic systems. The parasympathetic works in particular at rest and recuperation while the sympathetic works at efforts. Due to chronic stress, the autonomic nervous system can function worse, consequently, the regulation of the body may get disrupted and an imbalance between the two systems may arise.

Biofeedback as a Component of Treatment

It is important at the outset to emphasise that biofeedback is not at its most effective when used as a treatment in its own right, but should be integrated with other therapeutic interventions. It acts as an enhancer of the therapy, enabling the patient (and the therapist) to make more effective and rapid progress towards the rehabilitation goal. Furthermore, it is useful in that it helps the patient to reduce their reliance on the therapist and become more reliant on their own performance. Clearly, this is not fully achieved if the patient becomes reliant on the machine instead of the therapist! It can be used effectively to enable the patient to take some control or ownership over their rehabilitation - empowerment is an often used phrase in this context. The key to the success of biofeedback in rehabilitation is to use the device as an adjunct to therapy, to enable the patient to gain control without reliance on the therapist, and once gained, to maintain control without either the therapist or the machine. This approach is entirely in keeping with the general aim of modern physiotherapy, and the technology is an aid to the outcome, not a magical solution.

Complications

Biofeedback is a very safe and well-tolerated procedure that has minimal complications. If biofeedback is used at all times during therapy, there may be a drop in the performance following its discontinuation. It is, therefore, beneficial to practice the same techniques without the biofeedback equipment as part of the overall treatment for sustained improvement. If the patient does not practice the techniques often, then the treatment can have less than intended results over time and may require retraining.

Devices to receive in therapy

Electromyography

The principles of EMG biofeedback (EMGBF) are usefully reviewed, as a reasonable understanding of what the machine is doing will assist the therapist in determining the most appropriate machine settings and applications.

Read more about the Physiological principles

Indications

There are many indications for biofeedback. Stress urinary incontinence is an indication for biofeedback. We found in the literature that the addition of biofeedback to the training of the pelvic floor muscles for the treatment of stress urinary incontinence improved pelvic floor muscle function, reduced urinary symptoms, and improved the quality of life.

Pelvic floor muscle exercises and biofeedback are also effective treatments for men with erectile dysfunction.

Further, we found that EMG therapy is useful in enhancing knee extension after an ACL reconstruction but only in the early phase of rehabilitation after the reconstruction.

If we search for evidence for biofeedback as the treatment for headaches we found that biofeedback-related approaches to headache therapy fall into two broad categories: general biofeedback techniques (often augmented by relaxation-based strategies) and methods linked more directly to the pathophysiology underlying headache.

The use of general biofeedback-assisted relaxation techniques for headaches has been evaluated extensively. We can conclude that:

• Various forms of biofeedback are effective for migraine and tension-type headache;
• Outcomes with biofeedback rival outcomes with medication therapy;
• Combining biofeedback with medication can enhance outcomes;
• Despite efficacy in many patients, biofeedback fails to bring significant relief to a sizeable number of headache patients.

Biofeedback methods that more directly target headache pathophysiology have focused chiefly on migraine and tension-type headaches. These headache-specific approaches include blood volume pulse biofeedback, which has considerable supportive evidence, and electroencephalographic feedback. For tension-type headaches we found that biofeedback was more effective than headache monitoring, placebo, and relaxation therapies. The strongest improvements were found for the frequency of headache episodes. Further significant effects were observed for muscle tension. Biofeedback is also used for patients with migraine. This treatment is found effective to reduce the number of headaches per week but there were no changes in intensity, disability or length of headache.

Other indications for biofeedback are:

• CVA
• CVS/Fibromyalgia
• Chronic pain
• Neck pain
• Post traumatic stress syndrome
• Hypertension
• Headache – migraine – tension headache
• Balance disorders
• Attention Deficit Hyperactivity Disorder
• Epilepsy

Stabiliser

Stabilizer

A stabiliser has come into general use for stabilisation exercises for all parts of the body. A stabiliser is a pressure biofeedback unit and consists of an inelastic, three-section air-filled bag, which is inflated to fill the space between the target body area, a firm surface and a pressure dial for monitoring the pressure in the bag for feedback on position. The bag is inflated to an appropriate level for the purpose and the pressure is recorded. Movement of the body part off the bag results in a decrease in pressure while movement of the body part into the bag results in an increase in pressure. Its use in assessing the abdominal drawing-in action has become its most important use in relation to the treatment of problems for the local muscle system in patients with low back pain.

Use in lumbar stabilisation exercises

The patient is positioned in hook-lying. The feet remain flat and the arms are held alongside the body. The stabiliser is positioned under the lumbar lordosis. During exercises, the spine cannot make any movements. The transversus abdominis is contracted while doing the exercises to maintain an appropriate position. Below the woman is holding the feedback unit to monitor the amplitude of her spinal movement (based on the pressure change on the dial). ,

Computer-supported test and training systems

Computer-supported test and training systems Centaur (left) and Pegasus (right)

Centaur

With this device, the global torso musculature can be specifically strengthened and its coordination trained. Furthermore, for the first time, it is possible to directly train the local, deeper-lying muscles (stabiliser). CTT CENTAUR works based on the following active principles:

• By a coordinated tilt of the body, the torso needs to be stabilised against gravity.
• By tilting and rotating the body is put into an unstable position so that the balance analyser sends impulses to the deeper-lying muscles.
• Due to the upright posture during the training, the muscles are strengthened in the position in which they have to do the most supporting work.
• The precisely reproducible application of strain allows for targeted and exactly documentable therapy and training.

Pegasus

Computer-supported test and training system PEGASUS measure the range of motion and the strength profiles of the spine-stabilising musculature in all anatomical planes. Thus mobility and strength deficits and imbalances are identified. Based on these results, specific training (maximum strength, strength endurance, strength coordination and mobility training) of the sensorimotor systems of the lumbar spine can be realised. Thereby, existing muscular imbalances and performance deficits are tackled and resilience of the spine is reestablished.

Clinical Significance

Biofeedback techniques can potentially provide symptom relief and improve quality of life while also being safe and free of significant side effects. The methods allow patients to have some control over their disease, which is valuable in maintaining patient self-efficacy and overall well-being. With enough training sessions, patients can make changes that will last without the use of these instruments. Biofeedback can potentially also reduce the amount of medication a patient is taking, which can help patients avoid the problem of poly-pharmacy and limit side effects from other drugs. Clinicians may use biofeedback to control global physiologic reactions or specific muscle actions. Frequently targeted muscle groups are in the upper and lower limbs and the muscles used in gait. Muscles controlled by the autonomic nervous system, such as digestion, defecation, and urination, are also commonly selected. For urinary incontinence, pelvic floor muscles are the target, while in faecal incontinence, it focuses on the external anal sphincter. Biofeedback also has non-musculoskeletal targets such as anxiety and stress reduction. Biofeedback has also seen use in controlling the vasculature to reduce vasoconstriction, as well.