What is Biofeedback?
Several definitions of biofeedback have been proposed. Some emphasize the processes or procedures; others stress the goal or objectives, while others attempt to combine both elements. In the popular textbook, Biofeedback: A Practitioner’s Guide,¹ Olson proposed a comprehensive definition that includes both the process and the purpose of biofeedback as follows:
“(1) A group of therapeutic procedures that (2) utilize electronic or electromechanical instruments (3) to accurately measure, process, and “feed back” to persons (4) information with reinforcing properties (5) about their neuromuscular and autonomic activity, both normal and abnormal, (6) in the form of analogue or binary, auditory and/or visual feedback signals. (7) Best achieved with a competent biofeedback professional, (8) the objectives are to help persons develop greatest awareness and voluntary control over their physiological processes that are otherwise outside awareness and/or under less voluntary control, (9) by first controlling the external signal, (10) and then with internal psycho-physiological cues.”
A Rich History with Multiple Roots
The field of biofeedback has a rich history with multiple roots. Biofeedback in the United States dates back to the 1950’s with the convergence of many disciplines, factors, and antecedent events, including:
Instrumental conditioning of auto- nomic nervous system (ANS) responses
Psychophysiology
Behavior therapy and behavioral A second subtype, EEG biofeedback medicine
Stress research and stress-manage- ment strategies
Biomedical engineering
Electromyography (EMG), diagnostic EMG, and single motor unit control
Consciousness, altered states of con- sciousness, and electroencephalo- graphic (EEG) feedback
Cybernetics
Cultural factors
Professional development.²
Interest in biofeedback can be traced back to a time when researchers where searching for a means to decrease pathological autonomic responses, or alternately, increasing voluntary control, in conditions impacted by psycho-emotional processes.³˒⁴ At about the same time, interest in developing ways that individuals could learn to recognize and control muscle tension lead to the development of early biofeedback devices for urinary incontinence and muscular re-education.⁵ This interest has waxed and waned over the years but research and clinical outcomes often produced results that exceeded expectations and that still continued to baffle researches. In relation to electroencephalograph (EEG) feedback, the detection of alpha rhythms in 1930’s stimulated a great deal of interest but there was no technology or equipment to support the necessary research.
There is huge quantity of scientific literature supporting clinical practices that incorporate voluntary self-regulation of physiology such as heart rate, blood pressure, finger temperature, galvanic skin response, and surface electromyography (for EMG, alone, about 3000 books, articles, etc. were published by 1985).⁶ This interest for research and clinical applications has continued to grow. However, biofeedback has been relegated to a secondary role by pharmacological breakthroughs in the last two decades.
Recent revival of interest in EEG biofeedback has been fueled in part by: (1) the emergence of new technology and algorithms for recording and analysis of EEG signals, (2) increased caution and skepticism regarding pharmacological interventions, and (3) growing interest in safe, nontoxic, noninvasive, and self-regulatory ways of dealing with symptoms to achieve a sense of well being. The focus of biofeedback has been on resolution, not symptom suppression.
An Overview of Biofeedback Therapies
As practiced today, there are two major subtypes of biofeedback therapy. What was traditionally referred to as biofeedback, which included the use of such modalities as surface EMG, skin temperature, heart rate, blood pressure, and galvanic skin response, is now known as peripheral or somatic biofeedback. According to a standard textbook on biofeedback by Schwartz et al.,³⁴ a traditional focus of peripheral biofeedback has been on cultivating lowered arousal to treat a variety of disorders needing lower tension and arousal. Included in this category are headache, temporomandibular joint disorders (TMJ or TMD), Raynaud’s disease, various back pain and other musculoskeletal pain, anxiety disorders, and essential hypertension. More recent research and clinical experience by others have questioned this notion and presented other explanations for the efficacy of biofeedback. For instance, thermal biofeedback for Raynauds has been shown not to work through a lowered sympathetic arousal. Others have argued that poor posture and inability by chronic pain patients to calibrate muscle tension are more likely culprits. Therefore, the real benefit of biofeedback is to teach patients to become more physiologically aware of abnormal muscle tension and to adjust accordingly. Thus, patients can be abnormally aroused and yet remain relatively pain free. Within the last two decades or so, the applications of peripheral biofeedback have been extended to include neuromuscular re-education and gait training, biofeedback-assisted musculoskeletal therapy and neuromuscular re-education (for instance with stroke victims), and urinary and fecal incontinence. Finally, there is increasingly solid evidence that people can reduce severe pain associated with non-cardiac chest pain and, very probably, irritable bowel syndrome by learning to increase heart rate variability. The technique is currently called resonant frequency training (RFT) and was previously called respiratory sinus arrhythmia biofeedback (RSA).⁷˒⁸
The real benefit of biofeedback is to teach patients to become more physiologically aware of abnormal muscle tension and to adjust accordingly.
A second subtype, EEG biofeedback (also referred to as neurofeedback, neurotherapy, or neurobiofeedback) is classified as central biofeedback with its major focus on changing the electroencephalogram (EEG) or brain wave. This is a relatively newer field of biofeedback that has its roots dating back at least 25 years to the pioneering work of Elmer and Alice Green at the Menninger Institute on theta training and creativity,⁹ Thomas Budzynski in twilight learning¹⁰ and others. Progress was hindered then due to the crude technology and tools available at that time. However, this is no longer the case as advances in computer technology along with new technology and algorithms for recording and analysis of EEG signals are now available. This type of biofeedback has vast potential applications but is still in its infancy. To the extent that a medical or psychiatric disorder can be associated with a specific EEG deficit or pattern, EEG biofeedback can be used in restoring disordered pattern or deficit. An example is treating alcohol and addictive disorders with the alpha-theta protocol¹¹ where patients learn, with the help of auditory feedback, to increase the amplitude of alpha and theta brain wave. This procedure, together with imagery of the desired outcome, has successfully reduced or eliminated craving for the alcohol or substance of addiction for 70% to 80% of the addicts who completed the study. This protocol was developed based on previous research findings showing that some people with a predisposition to the development of alcoholism exhibit deficient alpha activity compared to normal control.¹²
Although peripheral biofeedback is well established as a treatment for chronic back pain, headache, and other musculoskeletal pain, EEG biofeedback has not yet been systematically employed to treat pain conditions. Most of the research on EEG biofeedback has been in areas other than pain. The notion that pain is associated with general cortical hyperexcitability and that altering slow cortical potentials through biofeedback might ameliorate this condition has been employed only in migraine patients.¹³ Research on pain-related brain rhythms has shown that an increase in theta and a reduction in beta power are related to better pain control.¹⁴
Efficacy of Biofeedback Pain Treatment
Several reviews of the efficacy of biofeedback treatments have been completed.¹⁵˒¹⁶˒¹⁷ The most recent review¹⁷ of biofeedback for pain related conditions in summarized in Table 1 and several are briefly elaborated in the following sections.
Effectiveness of Biofeedback-augmented Interventions on Pain
Proven effective in numerous clinical, controlled, comparative, and outcome studies with reasonably large groups and long follow-ups:
Migraine headache¹⁸
Tension headache¹⁸
Musculoskeletal orofacial pain and TMJ¹⁹
Shown to be effective by numerous clinical and some controlled studies but more comparative and outcome studies with larger groups and linger follow-ups are needed:
Stress and urge (as well as mixed stress and urge) urinary incontinence²⁰
Muscle tension related fecal incontinence²¹
Phantom limb pain (cramping and burning sensations)²²
Irritable bowel syndrome²³˒²⁴
Raynaud's syndrome²⁵˒²⁶˒²⁷
Posture related pain problems such as forward head thrust²⁸
Chest pain and other non-cardiac symptoms related to stress rather than heart problems²⁹
Clinical studies indicate effectiveness but many more studies with larger groups, longer follow-ups, and controls are required:
Premenstrual syndrome and dysmenorrhea³⁰
Pain from primary muscle spasms³¹
Subluxation of the patella and patelofemoral pain³²˒³³
Rheumatoid arthritis
Magnification of pain by stress and anxiety³⁴
Pelvic floor pain syndromes³⁵˒³⁶
Carpel tunnel syndromes⁵
Myofascial pain syndrome³⁷˒³⁸
Pain and spasticity due to exhaustion among sign language translators, musicians, factory workers, computer workers, etc.
A variety of studies indicate that applied psychophysiological interventions are frequently not effective in controlling these problems but some clinical work shows the opposite:
Cluster headaches³⁸
Phantom limb pain²² associated with shocking/shooting pain
Table 1. Current status of demonstrated effectiveness of biofeedback-augmented interventions on pain condition.
Migraine and Tension Headache
Numerous clinical and controlled studies have demonstrated the efficacy of psycho-physiological interventions, including biofeedback, for migraine and tension headache.²³˒³⁹˒⁴⁰ Comparative studies have shown that biofeedback is at least as, or more effective than standard interventions.⁴¹ Advantages of biofeedback include the absence of side or toxic effects, and the fact that unlike medication that has to be continued in order to maintain the analgesic effect, biofeedback treatment does not need to be continued once the patient has acquired the skill of self-regulation through the biofeedback treatment. Long term follow up studies have shown that the biofeedback therapies are effective for at least 5 years duration after the treatment is completed.⁴
Pediatric Headache
A recent comprehensive review of the published research on pediatric headaches concluded that thermal biofeedback is probably efficacious in the treatment of pediatric migraine, and EMG biofeedback is a promising approach for the treatment of tension headache in children.⁴² Some research also suggests that children with headache appear to benefit from the biofeedback therapies more so than their adult counterparts.
Musculoskeletal Orafacial Pain (TMJ)
A comprehensive review of the literature in this area concluded that biofeedback treatment of orafacial pain is effective when the pain is due to muscle rather than originating in the temporamandibular joint.¹⁹˒⁶˒³⁷ Several comprehensive studies have shown that biofeedback was as effective or better than splint therapy and that the gains were maintained for longer periods.⁴³˒⁴⁴
Musculoskeletal Back Pain
Unlike the efficacy research on headache, most studies on back pain utilized a mixed bag of interventions available at the study sites making it more difficult to tease out the effect of the biofeedback treatment. Reviews of studies of the efficacy of biofeedback on back pain have generally concluded that biofeedback is likely to help some patients with muscle related back pain, and at an overall improvement rate of about 65% relative to 33% for placebo and no improvement for no treatment controls.⁴⁵˒⁴⁶ Typically, sEMG is the primary biofeedback modality used to help patients relax a specific muscle group, to produce generalized relaxation response, or to correct stationery or moving postures that have been identified as contributing to the pain.⁴⁷
Persistent Pain in Older Adults
The prevalence of persistent pain in older adults (60+) has been estimated to be twice that of younger adults (under 60), however, the rate differs for different pain conditions.⁴⁷ Yet, older adults are under-represented in pain research and underserved in pain management programs. Studies have shown that older adults responded well to behavioral interventions that include biofeedback, typically sEMG training.⁴⁷ The sEMG training has been used to teach improved voluntary control of muscle groups in the specific areas of pain, primarily in the upper trapezius and lumbar paraspinal muscles. These studies usually take 8 to 12 sessions of biofeedback. No data is currently available on the use of other biofeedback modalities among older adults, and therefore, the efficacy is not known.
As has been previously alluded to, most of the efficacy research on pain conditions has been conducted with peripheral or somatic biofeedback, however, there has been some recent studies looking into the use of EEG biofeedback for the treatment of pain. The disorders to be discussed below utilized EEG biofeedback alone or in combination with peripheral biofeedback modalities.
Phantom Limb Pain
Two types of phantom limb pain amenable to biofeedback interventions have been identified: burning and cramping pain. Burning pain can be attributed to decreased blood flow to the residual limb while cramping limb pain is typically caused by spasms in the residual limb.⁴⁸ Studies have shown that nearly all amputees with cramping phantom pain can learn to recognize the relationship between their pain and the spikes in the sEMG of the residual limb and can learn to prevent the spikes from occurring. To the extent that the patient is able to prevent the spikes from occurring⁴⁶˒⁴⁸ (the goal of the biofeedback treatment) once a pain episode commences, the pain episode can be successfully aborted. The same holds true for burning pain. The primary difference is in the biofeedback modalities: sEMG for cramping pain and thermal biofeedback for burning pain. However, the success rate for cramping limb pain has been more encouraging since half of the patients with burning limb pain have not been able to significantly raise the blood flow in their residual limbs.⁴⁸
A case report⁴⁹ demonstrated how EEG biofeedback was used to successfully treat phantom limb pain that has been unsuccessfully treated by sympathectomy, sympathetic block, and physical medicine modalities including physical therapy and transcutaneous electrical stimulation (TENS). The focus was on decreasing higher frequency EEG while increasing lower frequency ones at the CZ site. One-year follow-up indicated the patient had remained relatively pain free and was enjoying a more active life.
EEG Biofeedback for Migraine Headaches
Psycho-physiological data support the concept that migraine is the result of cortical hypersensitivity, hyperactivity, and lack of habituation. As indicated by SCPs (slow cortical potentials), migraine sufferers display a habituation deficit that is hypothesized to be caused by brain stem related dysfunction.¹³ EEG biofeedback or neuro-feedback can be used to help patients acquire better control of the their high negative SCPs and to habituate. In a study of 10 children suffering from migraine without aura, the subjects were able to learn to control their SCPs within 10 sessions, resulting in a reduction of days with migraine and other headache parameters as compared to a waiting list control group.¹³ It should be noted, however, that this is a relatively small sample. More studies that would include other age groups are needed
Fibromyalgia
Fibromyalgia (FMS) is a complex and chronic, musculoskeletal pain disorder; characterized by widespread pain, hypersensitivity to palpation at specific tender points, sleep disturbance, fatigue, depression and other problems. Despite being one of the most common disorders treated at outpatient rheumatology clinics in North America, the etiology, patho-physiology, and effective treatment approaches are yet to be delineated. Recently, it has been suggested that FMS may be related to hypofunctional stress systems, particularly in the autonomic nervous system (ANS) and the hypothalamic-pituitary-adrenal (HPA) axis.⁵⁰ A large volume of animal and human research has implicated the involvement of the stress systems, ANS and HPA, in the regulation of the nociceptive experience.⁵⁰ Therefore, biofeedback, a form of psycho-physiological interventions, has a significantly relevant and potential role to play on the normalization of the stress reactivity.
A series of research studies in Canada on FMS has tested and confirmed that a psycho-physiological intervention combining sEMG biofeedback and EEG-driven stimulation is effective in the treatment of this disorder.⁵¹˒⁵²˒⁵³˒⁵⁴˒⁵⁵ These investigators identified diffuse muscular co-activation as a potential source of pain in FMS, and sEMG biofeedback has been successfully used to reduce the pain in these tender points.⁵¹˒⁵² However, relapse is likely unless the sEMG treatment is combined with EEG biofeedback.⁵⁴ These researchers-clinicians argued that unlike myofacial pain that appears to involve the peripheral nervous system, FMS appears to involve the central nervous system as well. Furthermore, psychological factors have a major role in selecting the right treatment for the FMS patients.⁵⁴ In this neural plasticity model of FMS,⁵³ the SCL 90-R, a psychometric instrument that measures psychological distress, is used to differentiate FMS patients into 3 groups with differing severity but similar pattern. Groups 1- and 2-type patients would tolerate more aggressive physical therapy, do better in exercise program, and benefit from EEG biofeedback (Alpha training for group 1 and Beta training for group 2). Group 3-type patients would require psychotherapy and also benefit from EEG biofeedback (Theta training) before starting physical treatments.⁵⁴
Biofeedback as a Diagnostic and Self-monitoring Tool
Although biofeedback is often thought of as a treatment tool and its usual definition does not include psycho-physiological assessment, it has been our experience (shared by other clinicians) that the biofeedback equipment can also be used for diagnostic and/or self-monitoring purposes. For example, a patient was referred to us with a chronic history of headaches that had interfered with his employment as a manager of a store. He had been seen by Neurology who placed him on Imitrex that gave inconsistent relief. He was hooked up to a biofeedback machine with bilateral placement of surface EMG electrodes on the upper trapezes. While taking a baseline, he was exhibiting slight increased muscle tension on the computer screen that corresponded to each inhaling breadth, subsiding when exhaling. This pattern was indicative of a braced breathing posture resulting in cumulative tension and muscle spasm, a likely contributor to his headache via the phenomenon of referred pain. He reported being totally unaware of this bracing posture. He was instructed to continue breathing but to do so without the muscle tension on inhaling. This was accomplished with the help of the visual feedback. After 6 sessions, he reported significant decrease in the episodes and intensity of the headaches and was able to eventually taper off his Imitrex.
Observing one’s real time psycho-physiological recordings on a screen while one is performing a task or simply sitting still often creates an increased self-awareness and impetus for change. It is one thing to tell a patient his/her standing posture is putting excessive stress and tension on the back. It is another to hook up the patient with sEMG electrodes in selected sites on the back so that he/she could personally observe real time changes in his/her sEMG recordings as he/she makes deliberate muscle tensing or relaxing associated with different standing postures. By simply observing how a corrected posture could reduce muscle tension may be sufficient impetus and feedback information for some patients to self-correct their posture. In practice, however, the guidance and several training sessions are needed to make the appropriate adjustment. Although the example given here refers to the use of sEMG electrodes to measure muscle tension, the same principles would apply to other biofeedback modalities as well.
Physiological Stress Profiling
Another common application is physiological stress profiling (PSP) while the patient is hooked up to several biofeedback modalities simultaneously, and subjected to a variety of stressful stimuli such as a sudden loud noise with little or no warning in order to produce a startle response, or asked to perform increasingly difficult mental arithmetic tasks. Observing which physiology goes up or down and remains up or down even after the stressor is removed could provide useful feedback to both the patient and the therapist on how the patient responds to stress. For instance, some patients may display increased heart rate and shallow breathing and others may show decreased finger temperature while still others may display significant bracing of the neck muscles when subjected to stressful stimuli. More important for chronic pain patients is the ability to rebound, that is, to return to normal, pre-stress levels after the stressful stimuli are removed. Inability to rebound is often a contributing factor to many pain conditions such as back and neck pain, and headaches.
Biofeedback as an Adjunctive Therapy for Pain Relief
Biofeedback can be used as the sole treatment for pain or as an adjunctive treatment in combination with other interventions. An example is to combine it with pain medication with the idea of tapering off the medications as the patient acquires better pain management skills through biofeedback. Biofeedback is often combined with psychotherapy or as a part of behavioral intervention, or as a modality in a multidisciplinary treatment center.
For example, a patient may be so distracted by his/her pain that relief with medication may be necessary before he/she can focus on doing the biofeedback but, as progress is made, the medication may be gradually reduced or eventually tapered off. There is some evidence that when combined with micro-current electrical stimulation, the combined therapies are more effective than either one alone.⁵³
In addition to reducing pain, biofeedback therapies can be used to treat pain-related symptoms such as depression, excessive fatigue, chronic anger, sleep problems, and excessive anxiety. Biofeedback may be used to address other issues that can affect the outcome of pain management such as: addiction to alcohol and pain medication, and weight reduction/ control.
A Typical Biofeedback Session
A typical feedback session consists of the following activities:
Pre-session assessment (progress since last visit, if applicable)
Goal for this session developed and identified.
Pre-session rating of pain etc.
Decision on biofeedback modality/ protocol to use.
Instruction to patient if applicable.
Implement the training/protocol (a session usually takes 30 to 50 min- utes, depending on the protocol).
Record observations.
Post-session rating of pain etc.
Feedback from patient regarding the session.
End session with instruction for next
session, if applicable.
Minimal instruction is usually provided to the patient. For example, the patient is instructed on how to interpret and react to the feedback (visual or audio) in achieving the target such as lower sEMG, higher alpha amplitude etc. All biofeedback procedures are based on operant conditioning principles.
More important for chronic pain patients is the ability to rebound, that is, to return to normal, pre-stress levels after the stressful stimuli are removed.
Selection of modality/protocol is based on the presenting problems, clinical interviews, review of medical chart, psychometric testing data, goals of training/ treatment, and in selected cases, a physiological stress profiling or qEEG brain mapping.
Professional/Certification Agencies
Following are associations that provide professional auspices and certification. For further information please visit their listed website.
International Society for Neuronal Regulation (ISNR). Official journal: Journal of Neurotherapy. Membership interest primarily in EEG biofeedback or neurotherapy. www.isnr.org
Association for Applied Psychophysiology and Biofeedback (AAPB). Official journal: Biofeedback and Self-regulation. Membership interest primarily in peripheral biofeedback but has an active section on EEG biofeedback. www.aapb.org
Biofeedback Certification Institute of America (BCIA). Separate certifications for peripheral biofeedback, EEG biofeedback, and other specialty areas. www.bcia.org
Conclusion
Biofeedback is a non-pharmacological intervention that can help patients modulate their pain experience by teaching them to change the underlying physiology which causes the pain, helping to decrease the anxiety which magnifies the perceived intensity of pain, and modulating how pain affects their functioning. It has no known side or toxic effects.
Biofeedback’s aim is to help patients acquire improved self-regulation of specific body physiology or EEG brain waves purported to relate to their pain conditions. When successfully treated, patients would be expected to report decreased pain, improved functioning and quality of life.
In some disorders that have been widely researched, such as migraine and tension headaches, up to 80% of patients could be expected to benefit significantly from biofeedback. The beneficial effects may last for 10 years or more—provided they continue to apply the physiological awareness skills they have acquired through this treatment. While most of the efficacy research has been with the use of peripheral modalities such as sEMG, central or EEG, biofeedback holds promise as a viable intervention for use with patients suffering from chronic pain.