Upon first seeing their MRIs, many people with spinal-cord injury (SCI) have said to themselves, "But everything below my injury can't be paralyzed! There's barely a notch in my spinal cord!"

Perhaps SCI’s cruelest aspect is its uncertainty. We wonder how our bodies could become so impaired through so little apparent damage, whether its lost functions might one day return, and what types of repairs are needed to regain them.

Since the 1970s, a passive neuromuscular training technique developed by Dr. Bernard Brucker, University of Miami, called the Brucker Biofeedback Method, has allowed many with SCI to regain functional abilities. 

This method uses visual “feedback” from an electromyography (EMG) device. Through sensitive electrodes placed over muscles, EMGs sense motor-action potentials (nerve “impulses” or signals) with great precision. The EMG visual display allows users and therapists to “see” subtle neural signals that reach the muscles from the brain, which the user is unable to sense. Seeing these signals enables trained therapists to choose specific rehabilitative techniques aimed at strengthening the signals until they produce a desired functional effect, e.g., the user can voluntarily contract a previously paralyzed muscle.

This technique has improved the quality of life for many with SCI by shedding light on one of its previously uncertain aspects: the cord's functional potential in its chronically injured state. However, as reparative treatments for chronic SCI move from the lab to the clinic, biofeedback’s benefits to the paralyzed community may broaden far beyond its present uses; they may be integral to emerging regenerative successes.

This two-part article explores biofeedback’s proven benefits and future potentials. 

How Biofeedback “Works”

Biofeedback is a form of operant learning, which uses a “reinforced stimulus” as a reward to encourage the subject to repeat a desired action. During biofeedback, the patient is requested to perform intended movements. Using a movable graph on a computer screen, the EMG provides visual feedback of neural signals that reach target muscles. The subject may need repeated attempts to “find” a neural pathway that delivers a signal. But even then the signal is often too weak for the subject to sense.

Once a pathway is found, the therapist directs the subject to make the EMG graph “grow.” This can only occur by increasing the strength of the motor signal that reaches the muscle. However, because the subject may not sense the signal, or signal variations may be too slight to be felt at first, EMG feedback is used to provide the “reinforced stimulus” necessary for operant learning to occur.

By teaching subjects how to reproduce, maintain and control EMG responses for maximum improvements in muscle function, EMG visual feedback – combined with behavioral conditioning techniques and rehabilitation – helps subjects “re-educate” their muscles. The control gained in one session is the starting point for the next.

SCI Applications

The Brucker Technique uses the Neuroeducator 3 EMG Biofeedback System, which allows therapists to identity subtle motor connections between the brain and the body that survived injury, or that have slowly repaired or rebuilt since being damaged.

Unlike biofeedback to enhance relaxation, control blood pressure, or control heart rate, SCI biofeedback requires equipment sensitive enough to monitor neural signals to within 1% of normal signal. In addition, biofeedback-trained therapists should know which muscles are needed to regain specific motor functions, the signal strength needed for specific muscles to function, and techniques for helping the subject find and develop these signals.

Subjects with SCI have regained many lost motor functions after biofeedback training. The results sometimes appear as miraculous. People who were told that they would never walk or use their hands have regained the ability to walk or feed themselves. However, motor improvements through biofeedback therapy require the patient to have specific physical conditions.

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