What Is Transcutaneous Electrical Nerve Stimulation (TENS)?

At a Glance:

  • TENS uses electrical stimulation to treat pain through a combination of factors, including the release of endorphins and overwhelming the pain signals with extra nerve impulses.
  • A TENS machine consists of a small stimulator box connected to two or more electrode pads by wires.
  • These electrodes are placed on or around the source or centre of where the person feels pain.
  • TENS machines have few if any negative side effects but may not work for all people.  They will not cure the cause of the pain, but may provide pain relief.
  • Some medical conditions or situations may prevent the use of TENS in the treatment of pain

What is a TENS Machine?

In addition to manual therapeutic techniques, such as joint or muscle manipulation and massage, physiotherapists may also utilise a number of specialist tools to help them treat people in a non-invasive manner.

A TENS machine is a device that utilises low voltage electrical current to offer pain relief. The electrical impulses appear to help block pain signals from reaching the brain, giving people suffering from chronic pain or other forms of long term discomfort a respite from their symptoms.

How a TENS machine actually blocks or reduces pain is not fully understood, but recent studies point to an interaction of a number of factors, including pain gate theory and endorphins. Endorphins are a natural pain reliever released in the brain and TENS appears to trigger increased production. 

Pain gate theory supposes that a nerve signal may be blocked or reduced in intensity by co-opting the nerve with other stimuli. Most people have experienced this effect in some way or another, such as rubbing your shin after you’ve just banged it into something. The shin pain is deadened thanks to the rubbing sensation that is muting the signal to the brain. The electrical currents from a TENS machine mimics this.

The electrical impulses are sent transcutaneously - meaning across or through the skin - so no medicine or invasive techniques are needed to treat pain. While TENS doesn’t hurt, the sensation, often described as a buzzing or tingling may be unpleasant to some people. 

A TENS machine is typically a small, portable unit made up of a battery powered stimulator about the size of a large mobile phone connected to at least two sticky electrode pads that attach to the skin around the source or location of the pain. Controls on the stimulator allow the user to alter and vary the intensity and duration of the impulses to achieve best effect.If your physiotherapist recommends TENS for your pain, they will typically work with you on the best placement for electrodes and the optimal settings so you can alleviate pain at home.  They are often available to hire, rather than purchase outright, and replacement pads are easily available. 

What Is Electrotherapy?

Electrotherapy refers to the use of external forms of energy (electricity, light and sound) for treatment. TENS is a widely used form of electrotherapy but it isn’t alone. 

Electronic Muscle Stimulation (EMS) utilises similar technology to TENS - a stimulator connected to a number of electrodes - to send electrical impulses into muscles causing them to expand and contract. EMS may be used for pain relief, to help build tone in wasted muscles, aid in recovery or prevention of injuries and help in the training of athletes.Therapeutic Ultrasound (TUS) utilises low frequency sound to cause vibration in tissue, stimulating blood flow and increased healing. Unlike TENS and EMS, TUS lacks a volume of quality scientific study proving its efficacy in treating musculoskeletal issues. While the therapy may have benefits, these have yet to be concretely proven.  At this stage, research suggests that the benefit of TUS is no greater than placebo. 

Percutaneous Electrical Nerve Stimulation (PENS) is a form of invasive electrotherapy. Much like TENS, PENS utilises electrical impulses to stimulate nerves but rather than utilising electrode pads, PENS utilises acupuncture-like needles to conduct the electricity.

What is TENS Used For?

Transcutaneous electrical nerve stimulation is used for the treatment of pain but it isn’t recommended as a treatment for all pain. The bulk of research into TENS that has been conducted shows that it has far more efficacy in treating chronic, (long lasting) pain than it is in treating acute pain. That said, TENS does appear to be an effective pain reliever for labour pains, essentially making it a non-invasive epidural.

For reasons not yet fully understood, TENS is not effective for everyone. Some people receive no benefit from nerve stimulation, whereas others may have an excellent response. Some people may find the buzzing or tingling sensation too unpleasant to maintain therapy.

While many people may be able to benefit from TENS therapy for pain relief, there are some instances in which TENS should not be used, such as:

  • Open wounds - electrode pads should never be applied on or around open wounds
  • Skin irritations - pads should not be placed on irritated skin. Some people may be allergic to the adhesive used on the pads. In this case special hypoallergenic pads may be available
  • Sensitive areas - pads should not be placed on or around sensitive areas, such as the eyes or genitals
  • Driving or operating heavy machinery - essentially anything you shouldn’t be doing while drunk, you shouldn’t attempt while using a TENS machine
  • In or around water - electricity and water don’t mix

Some conditions may also restrict the use of TENS in pain therapy. Although there are generally few, if any negative side effects of TENS, it may have negative effects on people with some health conditions or who have undergone certain procedures, such as:

  • Medical implants - TENS may interfere with electrical devices like cochlear implants, pacemakers, implanted cardiovascular defibrillators (ICD), implanted insulin monitors or pumps and the like 
  • Heart conditions - TENS is not recommended for people with severe heart disorders
  • Pregnant women (not in labour) - although TENS has proven effective for treating labour pain, the therapy should not be used during pregnancy

What Are the Benefits of TENS in Therapy?

The major benefit of TENS therapy is that it is a non-invasive pain control, meaning that your physiotherapist or GP can experiment with ways of treating you without the need for medications, surgery or other invasive techniques. Due to a lack of negative side effects, and the fact that TENS machines are easily portable, transcutaneous electrical nerve stimulation may be used at home whenever needed, without the risks of addiction or other side effects that may come with pain medicine.

Who Can Benefit From TENS?

TENS may be used to treat pain caused by a number of conditions, including but not limited to:

If you experience frequent or chronic pain but don’t want to resort to prescription medications or potentially invasive medical procedures to find relief, TENS may be for you.

Schedule an appointment to see a physiotherapist or your GP and see if electrotherapy may be right for you.

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