Stroke (Cerebrovascular Accident or CVA)

Assessment of condition

Overview

EMG biofeedback is frequently used for neuromuscular rehabilitation after a stroke has caused an upper or lower extremity to become weak or paralyzed. Weak or paralyzed arms or legs are actually the "victim" of the brain's inability to "send" the correct impulses down the spinal cord to the correct muscle to cause the muscle to contract or relax. Depending upon the amount of brain tissue ("nerve cells" or "neurons") that was injured or destroyed as a result of the stroke, patients can benefit marginally, significantly, or "somewhere in between." The underlying belief is that the human brain can display tremendous plasticity, meaning that the brain is malleable, adjustable, capable, and constantly changing, even as we humans age. If you are capable of learning something new, you may very well be capable of improving your arm, leg, or speech functioning.

Sensors

Typically, skin surface EMG sensors are utilized for neuromuscular re-education (neuromuscular rehabilitation).

Where sensors are placed

EMG sensors are placed over the weak, affected muscles. Often, agonists and antagonists may be monitored simultaneously. So, your biceps may be contrasted with your triceps because the biceps help you bend your arm at the elbow (elbow flexion) while the triceps help you straighten your arm (elbow extension). Similarly, an EMG sensor may be placed over your wrist or finger extensors with simultaneous placement of a second EMG sensor over your wrist or finger flexors. (The wrist extensors allow your hand to bend up at the wrist while the wrist flexors allow your hand to bend down at the wrist.)

Behavioral intervention

Learning and behavioral change

As in other forms of biofeedback, the principal of operant conditioning --- one of the most well-researched learning principles in the field of psychology --- appears to explain why EMG biofeedback is an effective intervention. If you think of recovery from stroke as a "relearning" process, the concepts become very clear. The stroke --- or cerebrovascular accident (CVA) --- has disrupted normal brain functioning. Some of the "old," well-learned, well-rehearsed motor patterns in the stroke patient's brain have been disrupted. New pathways must be established to substitute for the former, well-established pathways.

How does the process begin? The patient may think that his or her arm or leg is "dead" --- figuratively speaking. The patient may even attempt or think about attempting to move the arm, but becomes discouraged because the arm appears to be motionless. Because the patient cannot see the arm moving, he or she becomes unmotivated, discouraged, and sometimes despondent. Biofeedback provides immediate, "real-time" information about the brain's connection with that affected arm or leg. Even if the arm or leg does not appear to move, the EMG biofeedback system will verify if the patient's thinking about moving an arm or leg results in recruitment (meaning contracting or tensing) of a muscle, even if the amount  recruitment is miniscule.

Although the number of microvolts of EMG activity is not sufficient to move the affected arm or leg, it is definitely "a step in the right direction." And the patient becomes very enthusiastic and hopeful, knowing that the connection between the brain and the affected arm or leg still exists. Although the connection is initially weak, with continued repetition, the connection strengthens, greater control is achieved in terms of recruiting and inhibiting muscle activity, and eventually more voluntary control --- leading to productive movement --- begins to occur.

This newfound awareness of the ability to voluntarily recruit muscles adversely affected by the stroke is a key component to any patient's physical therapy (PT) and occupational therapy (OT). There are some rehabilitation facilities that would not think of providing therapy without EMG biofeedback as a valuable adjunct to traditional methods. EMG biofeedback can be helpful in both helping patients "recruit" (tense, contract) muscles as well as helping patients "inhibit" (relax) muscles. Inhibition is particularly important when patients display undue spasticity, "tone," or contractures.

Number of sessions

EMG neuromuscular rehabilitation, or neuromuscular re-education, or neuromuscular retraining are all terms that may be used interchangably. However, no matter the term used, the process is time-consuming. Consider the notion that in order for a human being to learn how to walk, for example, the "baby turned toddler" attempts to walk literally thousands of times before perfecting the skill of balancing on two feet and producing the trunk and lower extremity activity to be able to walk a few steps, albeit awkward at the beginning. Those motor programming skills develop slowly, with a great deal of trial and error, and continue to be perfected with great ease over a period of many years. The process of "re-learning" those motor skills is possible, but it requires patience, thoughtful, supervised "skill building" over a period of years.

Change in behavior

Goals

The most obvious goal would be partial and/or near-complete functional restoration of an arm or leg adversely affected by a stroke. There are many factors that contribute to success, however, not the least of which are (1) the location of the stroke in the brain ---whether it is in a crucial area, and (2) the amount of brain tissue --- the number of neurons --- that was destroyed as a result of the stroke.