Electrical stimulation, or ES, can enhance your recovery of muscle strength and function and reduce spasticity following a stroke. By providing a shock to specific muscles or muscle groups, ES allows the stroke survivor to better utilize affected arms or legs to perform motor skills. Physical and occupational therapists use ES as part of post-stroke rehabilitation programs in hospitals or outpatient centers. There also are a number of available ES products for home use.
When a person has a stroke, a blood vessel in the brain either ruptures or is blocked by a clot. Damage occurs to the brain tissue where oxygen is deprived, and often the motor cortex is affected. Because the brain is unable to send adequate messages, or electrical impulses, to the muscles of the affected area, the muscles may appear flaccid or spastic. The person may have complete or partial paralysis, and decreased range of motion in the joints can result. It is critical to begin therapy early following a stroke to maximize recovery and prevent complications.
Types of Electrical Stimulation
Electrical stimulation for stroke rehabilitation is different than electrical stimulation for pain reduction and acute muscle injuries. Functional electrical stimulation refers to ES in combination with use of a prosthesis. Transcutaneous electrical nerve stimulation provides pain relief and is not typically used for stroke rehabilitation. Electromyographic, or EMG, triggered neuromuscular electrical stimulation is a newer technology specific to muscle relearning in stroke rehabilitation. The EMG registers subtle muscle contractions when a patient attempts to move paralyzed muscles, and the electrodes then stimulate a stronger contraction.
Muscle Relearning with ES
Muscle relearning refers to the neurological process of perceiving and generating muscle contractions. Since strokes generally occur on either the right or left side of the brain, the result is that the person is impaired on one side of the body, or hemiplegia. The brain must relearn movements and sensations, and often the unaffected arm or leg works harder to compensate. EMG triggered neuromuscular ES applies biofeedback methods, so that the patient becomes more aware of subtle muscle contractions in the affected limb. This can result in improved voluntary muscle control. Traditional ES also is effective in muscle relearning simply by allowing the patient to feel the muscles contract.
Research on Electrical Stimulation in Stroke Rehabilitation
In general, research supports use of electrical stimulation in patients who have had a stroke. In a 1999 randomized clinical trial published in "Stroke," ES to the wrist extensor muscles resulted in significant increases in grip strength and upper extremity function. A 2010 study published in the journal "Stroke" recommends a minimum of 10 hours of ES per week as part of an acute rehabilitation program but found no significant differences in dosage. Functional ES with a neuroprosthesis may be more beneficial if you have minimal movement in your hand. EMG triggered NMES shows promising improvements in walking and hand function.