Functional Electrical Stimulation (FES)

Functional electrical stimulation (FES) is a treatment that uses electrical impulses to activate specific muscles and nerves. These impulses make muscles contract, to move a foot or lift an arm. You might choose this treatment option if you experienced a spinal cord injury. The stimulation sensation isn’t painful, but it can be unpleasant.

Overview

What is functional electrical stimulation?

Functional electrical stimulation (FES) is a form of treatment that sends an electric current to your nerves and muscles. This wakes up your nerves and tells your muscles to contract (tighten). FES helps restore muscle function and helps muscles move. FES is a treatment option for foot drop, weakness caused by damage to the brain or spinal cord, or conditions that cause muscle dysfunction.

While FES offers many benefits, it isn’t for everyone. The electric shock sensation that this treatment produces can cause discomfort but not pain. There is a range of intensity from the stimulation. You might not feel very low settings, or it can feel like a tingling sensation. Higher settings cause a pins and needles feeling and sometimes a burning sensation.

A healthcare provider will show you how to use an FES device and check in with you during your treatment to make sure you’re comfortable and the treatment is effective.

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What does functional electrical stimulation do?

Functional electrical stimulation uses small electrical currents or impulses to activate specific muscles and nerves. FES can help you:

FES is a way to exercise your muscle tissue. You might do this by walking, lifting weights or participating in a sport. Sometimes, certain injuries or conditions can make exercising or participating in activities challenging to impossible. FES is a way to help you build strength when traditional options don’t work for you.

What activities can functional electrical stimulation help me do?

Functional electrical stimulation can help you:

  • Move your hand to grasp and release objects.
  • Hold a fork to eat.
  • Hold a pen to write.
  • Stand, step and walk short distances.
  • Sit upright or improve posture.
  • Move from a sitting to a standing position.
  • Regain the sensations of pressure, touch and temperature.
  • Exercise.

What conditions does functional electrical stimulation treat?

Common conditions that functional electrical stimulation treats include:

For example, after an injury or stroke, an area of your body may not get the messages it needs from your brain to tell it to move, causing weakness or paralysis. FES targets those affected muscles. It sends an electrical current that makes your muscles contract and move. FES doesn’t cure paralysis, but it helps strengthen muscles that would otherwise not move on their own.

How does functional electrical stimulation help people with brain or spinal cord injuries?

Functional electrical stimulation improves your ability to move your muscles if you have a brain or spinal cord injury. For example, FES can contract your muscles to move your foot or lift your arm. The electrical impulse can block signals that send messages about pain to your brain. It can also restore or improve some bodily functions such as bowel and bladder regulation.

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Who is a candidate for functional electrical stimulation?

A healthcare provider will discuss whether functional electrical stimulation is right for you. You may be a candidate for FES if you:

  • Have muscle weakness.
  • Have limited to no movement in part of your body (paralysis).
  • Have an underlying condition that affects your central nervous system.
  • Experienced an injury that affects your movement.

To determine whether you’re a good candidate for this type of treatment, a healthcare provider will offer an assessment. They’ll see how your body responds to FES. In some situations, your body won’t respond, like if you have damage to nerve fibers between your muscles and spinal cord. This assessment takes about an hour in your provider’s office. If your body responds to FES, you’ll be a good candidate for the treatment.

FES isn’t for everyone. A healthcare provider might recommend other treatment options instead of FES if you have any of the following:

Talk with your provider about these conditions, other medical conditions you may have and any other concerns about whether FES is right for you.

Procedure Details

What are the components of functional electrical stimulation equipment?

Functional electrical stimulation equipment comes in all shapes and sizes. The type of equipment depends on the treatment location and the desired outcome.

Most FES devices include:

  • An external, small electrical box (called the neuromuscular electrical stimulator unit).
  • Wires that lead from the box and carry the electrical impulse. Some FES devices use wireless connectors that use radio waves to transmit electrical signals.
  • An electrode to which the wires attach.

The electrodes activate the targeted muscles or nerves. Electrodes can:

  • Attach to the surface of your skin with sticky pads.
  • Attach directly under your skin (percutaneous placement) during an office visit with your healthcare provider.
  • Fully embed deeper into your muscle (implant) or the area surrounding the targeted nerve. This requires outpatient surgery.

Your healthcare providers — which may include occupational therapists, physical therapists and speech-language pathologists (SLPs) — may recommend surface or percutaneous electrodes for short-term treatment, usually during early recovery and rehabilitation. If your treatment involves long-term goals, your provider may recommend implanting electrodes.

Your neuromuscular rehabilitation team will determine:

  • Which device is the right device for you.
  • What muscles or nerves need stimulation.
  • How much stimulation you need (voltage and stimulation pattern).

If you have any questions about the device or your treatment plan, talk to your provider.

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What does functional electrical stimulation feel like?

Functional electrical stimulation should be painless, but it can cause mild discomfort. The sensation you feel during FES can vary depending on the level of intensity. It can range from a tingling sensation to a burning sensation, and be strong enough to contract your muscles. Your healthcare provider will monitor the level setting to make sure it isn’t too intense and that you’re comfortable.

How long will I need functional electrical stimulation?

Everyone’s situation as to why they choose functional electrical stimulation treatment is different. You may need short-term rehabilitation over a few months or long-term, continuous treatment over several years to meet your goals.

For example, FES for spinal cord injury is a long-term therapy. Learning how to use it can take weeks or months. You’ll work with a rehabilitation therapist in a series of sessions to master the technology to meet your goals.

A healthcare provider will give you the best estimate on how long you’ll need FES treatment.

Risks / Benefits

What are the benefits of functional electrical stimulation?

Functional electrical stimulation can benefit you in many different ways, depending on your reason for treatment and your goals. Some of the most common benefits include:

  • Decreases the risk of fractures by building muscle mass.
  • Decreases fatigue and energy loss during activities.
  • Increases blood circulation.
  • Helps manage weight.
  • Regains lost bone mass.
  • Reduces muscle spasms and the effects of spasticity.
  • Encourages coughing to clear secretions, which reduces the risks of pneumonia and other lung infections, as well as choking hazards.
  • Prevents and reverses muscle atrophy (shrinking and weakening of tissue due to lack of use).
  • Improve standing and walking ability.

FES can increase a person’s independence and confidence after an injury or diagnosis. It can also reduce your risk of future injuries like falls.

What are the risks or complications of functional electrical stimulation?

The risks of using an external functional stimulation device include:

  • Discomfort during treatment.
  • Skin irritation at the site of electrodes.
  • Worsening spasticity.
  • Strained muscles.

For some, the feeling of FES may prevent them from continuing treatment. It can take some time to get used to the sensations of FES.

The risks of implanted functional electrical stimulation include:

  • Irritation or infection at the site of electrode placement.
  • Scar tissue that forms around the electrode (encapsulation).
  • Broken wires.
  • Electrodes that move after placement.

Your neuromuscular rehabilitation therapist will work with you to determine the proper type and placement of electrodes to avoid complications. Check in regularly with your care team to reduce your risk. Be sure you know when to contact your provider if you suspect an issue.

Because of the metal used in FES systems (from the wires and other components), you may not be able to undergo magnetic resonance imaging (MRI) if you have an implanted FES system. MRI is a useful tool in diagnosing health conditions. If this is a concern, discuss this with your provider.

Recovery and Outlook

What can I expect if I do functional electrical stimulation?

Many people who receive functional electrical stimulation improve the use of their muscles and experience a better quality of life. You may be able to sit up, stand, walk short distances, use your hands and restore some bodily functions if a condition or injury affected those parts of your body.

You’ll need to regularly follow up with your healthcare providers to adjust the position of the electrodes or the strength of the stimulation. These changes might be necessary as your muscles get stronger and your nerves react to the varying stimulation levels.

When to Call the Doctor

When should I contact my healthcare provider?

Let your healthcare provider know if the sensation you feel during functional electrical stimulation is unpleasant. Some people can’t tolerate how it feels, which is OK. Other treatment options are available if FES isn’t the right option for you.

Also, contact a healthcare provider if you feel pain or have skin irritation at the electrode site while receiving functional electrical stimulation. Your provider may be able to use a different type of electrode or change the stimulation to solve the problem.

Additional Common Questions

What is functional electrical stimulation cycling?

Functional electrical stimulation can help you exercise on stationary bicycles. This is known as FES cycling. Electrical stimulation targets your leg muscles in a pattern that helps your muscles contract. This stimulation pattern allows you to use your legs to pedal the bicycle. These bicycles are adaptive, so you can use them while in a wheelchair, for example. This is a beneficial option if you have muscle weakness or limitations that prevent you from participating in cardiovascular exercises.

What is the difference between TENS and FES?

Transcutaneous electrical nerve stimulation (TENS) and functional electrical stimulation (FES) are similar stimulation treatments, but the nerves they target differ.

  • TENS assists your sensory nerves to improve muscle tone and reduce pain. TENS doesn’t cause muscles to contract.
  • FES works with your motor nerves to allow muscles to contract and move.

A note from Cleveland Clinic

A big misconception about functional electrical stimulation is that it hurts. While the treatment is technically “painless,” the sensation you feel might be uncomfortable. It can take some time to get used to. FES has many benefits to your muscles and overall health. It can even improve your confidence and prevent falls. Your provider will let you know if you’re a good candidate for FES and provide instructions on how to use an FES device. Regularly follow up with your provider to monitor how well the treatment works and make adjustments, if necessary.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 12/15/2023.

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