Functional Electrical Stimulation (FES) uses low energy electrical pulses to artificially generate body movements in individuals who have been paralyzed due to injury to the central nervous system. FES can generate muscle contractions in paralyzed limbs to produce functions like standing, walking, grabbing, and even bladder voiding.
FES was originally used to develop neuroprostheses, devices that can substitute a motor or sensory function that is damaged — like cochlear implants. The user can activate the device each time they wanted to generate the desired function.
FES for SCI
Restoration of limb function and organ function is the main application of FES, but it can also be used to manage pain, pressure, and sore prevention. FES has allowed individuals with paraplegia to walk, stand, restore hand grasp function, and restore bowel and bladder functions.
High-intensity FES of the quadriceps muscles allows individuals with complete lower motor neuron lesion to increase muscle mass and muscle fiber diameter, improve the ultrastructural organization of contractile material, and to participate in assisted stand-up exercises.
Fracture of leg bones is possible due to loss of bone mineral density. Also, FES can trigger autonomic dysreflexia in upper-level injuries. People with severe spasticity, contractures, or osteoporosis are not good candidates.
Walking: FES bikes allow people with little or no voluntary leg movement to pedal a stationary leg-cycle called an ergometer. Computer generated, low-level electrical pulses are transmitted through surface electrodes to the leg muscles. This causes coordinated contractions and the pedalling motion.
Bowels: Sacral stimulators are surgically implanted FES systems for on-demand control of the paralyzed bladder and bowel. The stimulator, called the Finetech-Brindley device, has a strong track record for improving bladder and bowel control in the vast majority of users. These have been implanted mostly in Europe.
In 1999, a company called NeuroControl licensed the Brindley system and got FDA approval as the Vocare system. A company called NDI Medical more recently obtained the marketing rights to Vocare in the United States.
Upper Arms: 15 years ago, the FDA approved an FES implant system to restore some hand and arm function to quadriplegics. The FreeHand system was well received and people living with paralysis gained significant function in grip, writing, eating, computer work, etc. NeuroControl dropped this product from the market.
Walking: There is a commercially available device called Parastep that is FDA approved for some paraplegics (T4 to T12 ) Parastep facilitates stepping by firing leg muscles and uses a front-wheeled walker fitted with a control pad.
Cleveland FES Center offers the FES Resource Guide that was created with the PVA on a variety of international programs that deal with FES research and delivery.
Findings from a 2014 FES General Study show: (1) Electrical stimulation of the peripheral and central nervous system may be used for rehabilitation and management of complications following spinal cord injury. (2) Electrical stimulation may improve the functional status and quality of life of many persons with spinal cord injuries. (3) Many of the electrical stimulation strategies are already commercially available, while others are being tested in human and laboratory studies. (4) Electrical stimulation should be routinely considered as part of the rehabilitation and medical management of eligible persons with spinal cord injuries. (Ho, 2014)
The preliminary results of an at-home FES experiment confirmed that FES, mediated by ILC, successfully assisted participants’ completion of functional tasks and training transferred to tangible changes in motor performance. Finally, the feasibility of using low-cost, user-friendly sensing approaches and arm support mechanisms that can be used in conjunction with FES-assisted tasks was established and comprise an important step towards the transference of such a rehabilitation system to the home. (Kutlu, 2017)
There are other options for at-home physical maintenance using FES for long-term denervated degenerated muscles. (Kern, 2014)
The results of another home-based FES experiment from 2010 show that 20 of 25 patients completed the 2-year program, which resulted in (a) a 35% cross-sectional increase in area of the quadriceps muscle. (Kern, 2016)
General Information on EMS
Electrical muscle stimulation (EMS), also known as neuromuscular electrical stimulation (NMES) or electromyostimulation, is the elicitation of muscle contraction using electric impulses.
The impulses are generated by a device and are delivered through electrodes on the skin near to the muscles being stimulated. The electrodes are generally pads that adhere to the skin. The impulses mimic the action potential that comes from the central nervous system, causing the muscles to contract.
EMS is used for rehabilitation purposes, for instance in physical therapy in the prevention of disuse muscle atrophy which can occur for example after musculoskeletal injuries, such as damage to bones, joints, muscles, ligaments and tendons. This is distinct from transcutaneous electrical nerve stimulation (TENS), in which an electric current is used for pain therapy.
In the United States, EMS devices are regulated by the U.S. Food and Drug Administration (FDA).
Ho, C.H. et al., 2014. Functional Electrical Stimulation and Spinal Cord Injury. Current neurology and neuroscience reports.Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4519233/ [Accessed October 8, 2018].
Kern, H. & Carraro, U., 2014. Home-Based Functional Electrical Stimulation for Long-Term Denervated Human Muscle: History, Basics, Results and Perspectives of the Vienna Rehabilitation Strategy. Current neurology and neuroscience reports.Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749003/ [Accessed October 8, 2018].
Kern, H. et al., 2016. Home-based functional electrical stimulation rescues permanently denervated muscles in paraplegic patients with complete lower motor neuron lesion. European Journal of Internal Medicine. Available at: https://moh-it.pure.elsevier.com/en/publications/home-based-functional-electrical-stimulation-rescues-permanently- [Accessed October 8, 2018].