Functional electrical stimulation (FES), also called functional neuromuscular stimulation (FNS) or neuromuscular electrical stimulation (NMES), is a medical technique that uses electricity to stimulate a patient's muscles or nerves for therapeutic purposes. It has proved effective in helping patients recover from or manage numerous different muscular or neurological ailments, including stroke, cerebral palsy, muscular dystrophy, spinal cord injury, and multiple sclerosis.
The use of electricity to stimulate nerves in order to restore physical functioning dates back to the early 1960s, when W. T. Liberson and his colleagues developed an electrotherapy technique to treat foot drop, a common result of neurological or muscular trauma. Damage to the brain, spinal cord, nerves, or muscles, as from a stroke or a degenerative disease such as muscular dystrophy, can result in the patient's inability to raise the front of his or her foot while walking. Liberson developed a device that sensed when the foot was raised from the ground, at which point it applied surface stimulation to the peroneal nerve, which connects to the muscles of the foot, causing the foot to flex and thus allowing the patient to walk normally. Liberson and colleagues originally called the technique “functional electrotherapy”; a year later, J. H. Moe and H. W. Post coined the term “functional electrical stimulation” in a 1962 paper.
Since then, FES has been used to treat numerous disorders affecting muscles, nerves, or both, through either surface stimulation or implanted devices. Neurological conditions that benefit from FES include strokes, multiple sclerosis, cerebral palsy, and paralysis resulting from spinal cord injuries. In patients who are struggling to regain physical functioning during stroke recovery, applying electrical stimulation to affected areas activates the nerves that cause the muscles to move, which both rebuilds muscle strength and helps the brain relearn how to initiate the movement on its own. In cases of multiple sclerosis, FES can improve the functioning of damaged nerves that control various muscle groups. For patients with cerebral palsy, FES can improve muscle control and reduce spasticity in the extremities. Multiple sclerosis and cerebral palsy patients, like those who have had strokes, are also prone to foot drop, for which FES remains a common treatment.
For patients experiencing paralysis due to spinal cord injury, FES can be used to exercise the muscles of paralyzed limbs, thus preventing atrophy and increasing overall fitness. In some cases, it may restore some level of mobility and control over bodily functions or even allow paralyzed extremities to function with assistance. One notable case was that of Nan Davis, a young woman who was in a car crash in 1978, on the night of her high school graduation, and was paralyzed below her rib cage. While attending Wright State University in Ohio, Davis volunteered for an experimental program headed by Jerrold Petrofsky, a biomedical engineering professor at the school. In 1983, with the aid of a device developed by Petrofsky that used FES to stimulate the muscles in her legs, Davis was able to walk across the stage at her college graduation to receive her diploma.
FES has also shown success as a treatment for disorders that affect the muscles themselves, such as the various types of muscular dystrophy, which are a group of diseases in which the muscles grow progressively weaker. As in cases of muscular atrophy due to neurological causes, FES can be used to exercise the affected muscles, halting deterioration and improving muscle strength.
—Randa Tantawi, PhD
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