Functional electrical stimulation
Encyclopedia
Functional electrical stimulation (FES) is a technique that uses electrical currents to activate nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...

s innervating extremities affected by paralysis resulting from spinal cord injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...

 (SCI), head injury
Head injury
Head injury refers to trauma of the head. This may or may not include injury to the brain. However, the terms traumatic brain injury and head injury are often used interchangeably in medical literature....

, stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

 and other neurological disorder
Neurological disorder
A neurological disorder is a disorder of the body's nervous system. Structural, biochemical or electrical abnormalities in the brain, spinal cord, or in the nerves leading to or from them, can result in symptoms such as paralysis, muscle weakness, poor coordination, loss of sensation, seizures,...

s. FES is primarily used to restore function in people with disabilities
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...

. It is sometimes referred to as Neuromuscular electrical stimulation (NMES).

History

FES was initially referred to as Functional Electrotherapy by Liberson, and it wasn't until 1967 that the term Functional Electrical Stimulation was coined by Moe and Post, and used in a patent entitled, "Electrical stimulation of muscle deprived of nervous control with a view of providing muscular contraction and producing a functionally useful moment". Offner's patent described a system used to treat foot drop
Foot drop
Foot drop is the dropping of the forefoot due to weakness, damage to the peroneal nerve or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. It is characterized by the inability or difficulty in moving the ankle...

.

The first commercially available FES devices treated foot drop by stimulating the peroneal nerve during gait. In this case, a switch, located in the heel end of a user's shoe, would activate a stimulator worn by the user.

Spinal Cord Injury

Injuries to the spinal cord interfere with electrical signals between the brain and the muscles, resulting in paralysis below the level of injury. Restoration of limb function as well as regulation of organ function are the main application of FES, although FES is also used for treatment of pain, pressure, sore prevention, etc.

Some examples of FES applications involve the use of Neuroprostheses that allow people with paraplegia
Paraplegia
Paraplegia is an impairment in motor or sensory function of the lower extremities. The word comes from Ionic Greek: παραπληγίη "half-striking". It is usually the result of spinal cord injury or a congenital condition such as spina bifida that affects the neural elements of the spinal canal...

 to walk, stand, restore hand grasp function in people with quadriplegia
Quadriplegia
Tetraplegia, also known as quadriplegia, is paralysis caused by illness or injury to a human that results in the partial or total loss of use of all their limbs and torso; paraplegia is similar but does not affect the arms...

, or restore bowel and bladder function.

Stroke

FES is commonly used in foot drop
Foot drop
Foot drop is the dropping of the forefoot due to weakness, damage to the peroneal nerve or paralysis of the muscles in the anterior portion of the lower leg. It is usually a symptom of a greater problem, not a disease in itself. It is characterized by the inability or difficulty in moving the ankle...

 neuroprosthetic devices.

In the acute stage of stoke
Stoke
-United Kingdom:*Stoke is one of the most common place names in the United Kingdom and in historical documents.Originally from the Old English 'stoc' meaning 'place', it came to be used in two special senses, i) a religious place and ii) a secondary settlement It can refer to any of the following...

 recovery, the use of cyclic electrical stimulation has been seen to increase the isometric strength of wrist extensors. In order to increase strength of wrist extensors, there must be a degree of motor function at the wrist spared following the stroke and have significant hemiplegia
Hemiplegia
Hemiplegia /he.mə.pliː.dʒiə/ is total paralysis of the arm, leg, and trunk on the same side of the body. Hemiplegia is more severe than hemiparesis, wherein one half of the body has less marked weakness....

. Patients who will elicit benefits of cyclic electrical stimulation of the wrist extensors must be highly motivated to follow through with treatment
Treatment
Treatment may refer to:* Treatment, therapy used to remedy a health problem* Treatment, a process or intervention in the design of experiments* Treatment group, a collection of items or individuals given the same treatment in an experiment* Water treatment...

, After 8 weeks of electrical stimulation, an increase in grip strength can be apparent. Many scales, which assess the level of disability
Disability
A disability may be physical, cognitive, mental, sensory, emotional, developmental or some combination of these.Many people would rather be referred to as a person with a disability instead of handicapped...

 of the upper extremities following a stroke, use grip strength as a common item. Therefore, increasing strength of wrist extensors will decrease the level of upper extremity disability.

Patients with hemiplegia
Hemiplegia
Hemiplegia /he.mə.pliː.dʒiə/ is total paralysis of the arm, leg, and trunk on the same side of the body. Hemiplegia is more severe than hemiparesis, wherein one half of the body has less marked weakness....

 following a stroke commonly experience shoulder pain and subluxation; both of which will interfere with the rehabilitation process. Functional electrical stimulation has been found to be effective for the management of pain and reduction of shoulder subluxation, as well as accelerating the degree and rate of motor recovery. Furthermore, the benefits of FES are maintained over time; research has demonstrated that the benefits are maintained for at least 24 months.

Other

Electrical stimulation for the purpose of helping persons with paralysis of the arms or legs mainly focuses on the neuromuscular transmission peripherally. E-stim can also be used for central nervous system stimulation to hasten awakening from coma or the vegetative state. There is a long history of neurosurgeons who have implanted electrodes into the brain and spinal cord, especially in Japan, for increasing cerebral blood flow and certain neurotransmitters in persons in long term coma states.

Beginning in 1991 in Greenville, North Carolina (East Carolina University
East Carolina University
East Carolina University is a public, coeducational, engaged doctoral/research university located in Greenville, North Carolina, United States. Named East Carolina University by statute and commonly known as ECU or East Carolina, the university is the largest institution of higher learning in...

) and shortly after that in Charlottesville,Virginia (University of Virginia
University of Virginia
The University of Virginia is a public research university located in Charlottesville, Virginia, United States, founded by Thomas Jefferson...

), the right median nerve has been used as a portal to help awaken injured human brains. Trains of differentiated square electrical pulses at 40 Hz (a frequency for upregulation of the thalamus), 20 seconds on and 40 seconds off, have been applied to the palmar side of the right wrist for transdermal stimulation of the right median nerve at low amplitudes, enough to produce contraction of the thumb. Battery powered FDA approved electrical neuromuscular stimulators have been used in these research projects connected by wires to the pair of right wrist electrodes embedded in a custom made plastic orthosis to localize the stimulation target. The right median nerve was selected as the electrical portal as there is large cortical representation of that nerve in the dominant left cerebral hemisphere. By subcortical connections, the transmitted signals go to Broca's motor/speech planning area (whether the person is right or left-handed, the majority are left hemisphere dominant). Awakening from deep coma from motor vehicle crashes with closed head injury in the Glasgow Coma Scale range of 4-6 can be expected to respond in half of the treated cases after two to four weeks of 8 hours/day electrical treatment,if started within one to two weeks of the severe brain trauma. The advantage of the shorter than expected period of unconsciousness is a quicker start into a neurorehabilitation program to encourage ambulation and talking.

Over the last decade, this RMNS project has spread from the USA East Coast to Central Japan, parts of Europe, and most recently in 2005 to Shanghai, China.

Functional electrical stimulation (FES) of paraplegics allows paraplegics with complete paralysis due to spinal cord injury at the thoracic level of their spinal cord to walk distances that average 450 meters per walk under some training procedures and 110 meters per walk when undergoing less demanding training, when using the noninvasive Parastep FES system that received the USA FDA approval in 1994. Certain such patients can walk one mile (1.6 km) using that same system. FES for ambulation also shows improvements in blood flow to lower extremities and in other medical and psychological parameters including bone density.

Further reading

  • Crago P.E., Lan N., Veltink P.H., Abbas J.J., Kantor C.K. (1996) “New control strategies for neuroprosthetic systems”, J. Rehab. Res. Dev., Vol. 33, No. 2, 158-172.

  • Crago P.E., Mortimer J.T., Peckham P.H. (Jun 1980) “Closed-loop control of force during electrical stimulation of muscle”, IEEE Transactions on Biomedical Engineering, Vol. 27, No. 6, 306-12

  • Peckham P.H., Keith M.W. (1992) “Motor prostheses for restoration of upper extremity function” Ch 8 in Neural Prostheses. Replacing Motor Function After Disease or Disability. R.B. Stein, P.H. Peckham and D.B. Popovic Editors.

  • Peckham P.H., Keith M.W., Freehafer A.A. (1988) “Restoration of functional control by electrical stimulation in the upper extremity of the quadriplegic patient,” J. Bone Joint Surgery, Vol. 70-A, 144-148

  • Peckham P.H., Marsolais E.B., Mortimer J.T. (1980) “Restoration of key grip and release in the C6 tetraplegic patient through functional electrical stimulation”, J Hand Surg [Am].Vol. 5, No. 5, 462-9.

  • Powell J., Pandyan D., Granat M., Cameron M., Stott D. J. (1999) "Electrical stimulation of wrist extensors in poststroke hemiplegia," J of the American Heart Association, Vol. 30, 1384-1389.

  • Cooper E.B., Scherder E.J.A., Cooper J.B (2005) "Electrical treatment of reduced consciousness: experience with coma and Alzheimer's disease," Neuropsyh Rehab (UK).Vol. 15,389-405.

  • Cooper E.B,& Cooper J.B. (2003) "Electrical treatment of coma via the median nerve," Acta Neurochirurg Supp, Vol. 87, 7-10.

  • Klose K.J., Jacobs P.L., Broton J.G., Guest J.G., Needham-Shropshire B.M., Lewohl N., Nash M.S., Green B.A (1997) "Evaluation of a training program for persons with SCI paraplegia using the Parastep-I ambulation system, Part 1: Ambulation performance and anthropometric measures", Arch. Phys. Med. Rehab., Vol. 78, 789-793.

  • Lichy A., Libin A., Ljunberg I., Groach L., (2007) " Preserving bone health after acute spinal cord injury: Differential responses to a neuromuscular electrical stimulation intervention", Proc. 12th Annual Conf. of the International FES Soc., Philadelphia, PA, Session 2, Paper 205.


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External links

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