Biofeedback is a way to gain control of physical processes that are not normally under conscious control. For example, people can learn to warm their hands by watching a thermometer while focusing mental activity on trying to get the temperature to increase by consciously relaxing to increase blood flow to the hands. In general, instruments are used to give “biofeedback”, on temperature, pulse rate, electrical signals from muscle activation (EMG), electrical signals from the heart (EKG), electrical signals from the brain (EEG) etc. Usually biofeedback is done in the office of a professional who has professional equipment.
Biofeedback is an established technique for overcoming some forms of chronic pain [Fisher]. For example, it has been shown to be effective for 63% of people suffering from migraine headaches [Sargent]. The type of biofeedback used for this study was simply hand temperature! The participants were trained to say phrases like: “I feel quite quiet . . . I am beginning to feel quite relaxed . . . My feet feel heavy and relaxed . . . My ankles, my knees, and my hips, feel heavy, relaxed, and comfortable . . . My solar plexus, and the whole central portion of my body, feel relaxed and quiet . . . My hands, my arms, and my shoulders feel heavy, relaxed and comfortable. . . . My neck, my jaws, and my forehead feel relaxed . . . They feel comfortable and smooth . . . My whole body feels quiet, heavy, comfortable and relaxed. I feel quite relaxed . . . My arms and hands are heavy and warm . . . I feel quite quiet . . . My whole body is relaxed and my hands are warm, relaxed and warm . . . My hands are warm . . . Warmth is flowing into my hands, they are warm . . . warm.”[Sargent]. These experiments were done with a trainer, but since all that is needed is something to measure hand temperature, you, like many others, can do it at home.
Hand temperature biofeedback has also been successfully used to treat reflex sympathetic dystrophy, a form of causalgia, which causes chronic pain. “Over the 18 treatment sessions the patient learned to emit a reliable hand warming response of 1 to 1.5°C. Coincident with his learning, the pain in
his hand and arm decreased markedly and remained absent at 1-year follow-up.” [Blanchard]. In another study all subjects spent a total of 4 to 8 weeks practicing the training exercises at home and successfully demonstrated hand warming by increasing skin temperature anywhere from 2 to 18 degrees F to an average of 93.5 F. Odawara et al. used computerized EMA to show that biofeedback could improve the symptoms of migraine, including psychological stress and headache-related disability.
I was personally trained to raise my hand temperature by a biofeedback expert at Sansum Clinic with similar phrases. It is now easy for me to do it on my own with a thermometer and my experience is that most people could learn to do it with practice. An electronic thermometer with a digital display is convenient. For example, the Temperature Biofeedback Digital Numeric Thermal Trainer available for $21.95 at Amazon works well for me. It took me about 4 ten minute sessions to learn to do it. The people I know who have used it to overcome chronic pain have done it three or more times a day. They generally prefer a cell phone based thermometer.
Custom biofeedback devices for hand temperature are being developed in Paul Hansma’s lab at UCSB. You can find out more about these on the Hansmalab website.
Several other types of biofeedback have also been shown clinically to be effective for chronic pain. A 2016 Meta-analysis concluded: “This is the first meta-analysis on the efficacy of biofeedback treatment for chronic back pain using the current standard recommendations to examine the following outcomes: pain intensity, reduction of muscle tension (EMG), depression, cognitive coping, and disability. The present results indicated that except for disability, (additional) biofeedback treatment led to improvements on all outcome measures in the short and long terms.”[Sielski] An earlier systematic review and meta-analysis of randomized controlled trials found, for example, an effect size of 0.74 for EMG biofeedback [Morley]. A 2016 Nature Reviews article looked at many types of closed-loop brain training: the science of neurofeedback [Sitaram].
The significance of Biofeedback training is not only that it can help with chronic pain directly, but more fundamentally that it shows that it is possible to gain control over normally unconscious processes such as hand temperature or heart rate or muscle tension. This is what we want to achieve: control over the normally unconscious process of generating the experience of Pain. This is the goal of Retraining the Brain away from Chronic Pain.
Biofeedback with real time functional Magnetic Resonance Imaging, rtfMRI
There have been many peer-reviewed research studies about imaging pain, including chronic pain, with fMRI [a review and meta analysis: Peyron, et al.] [Otti et al.][Kupers, et al.]. But of even more significance for chronic pain patients has been the use of real time functional Magnetic Resonance Imaging, rtfMRI, as a feedback gadget for retraining the brain. Using rtfMRI, chronic pain patients at Stanford were trained to control activation in the rostral anterior cingulate cortex (rACC) and reported decreases in the ongoing level of chronic pain after training. [deCharms, et al.]. It has been reported, based on fMRI imaging, that the areas involved in different sorts of pain can be different [Makin, S] [Wager, T] and that in chronic pain there is a growing involvement of areas involving emotion [Baliki, M N]. But fMRI studies of chronic pain are in their infancy.