The Southeastern Spine Institute

TENS Units & NMES Units

A TENS unit is a non-invasive nerve stimulation device. In fact, TENS stands for Transcutaneous Electrical Nerve Stimulation. TENS devices use very small doses of electric current to promote natural pain relief.

TENS units send electrical pulses from an externally applied source. The pulses race across the surface of your skin to your nerve strands, where they stimulate the nerves. A TENS unit works because the pulses effectively “block the line,” preventing pain signals from reaching your brain.

TENS units are not just devices to temporarily reduce your pain; the electrical pulses help stimulate your body’s natural defense against pain. The electrical current triggers your body to produce more of its own painkillers, known as endorphins.

These devices are predominately used for acute and chronic nerve-related pain. Your physician may prescribe a TENS machine as an alternative to, or in addition to, pain medication. It effectively can help control your pain. TENS units are often small, portable devices that are convenient to use at home or work.


A NMES unit is a muscle stimulator. NMES stands for Neuro-Muscular Electrical Nerve Stimulation. These external devices are used to reduce muscle spasms, tone weak muscles and assist in the healing process.

Originally, NMES units were used for preventing atrophy, when muscle wastes away from disuse. The primary recipients were people on long-term bed rest, such as patients who had to be immobilized after a major surgery or accident. Today, these devices have found more uses within the medical field.

While they are similar to TENS units in that they are both externally applied devices, NMES units emit a stronger and wider electrical pulse. The NMES pulse stimulates targeted muscles to contract repeatedly over a specific period of time.

The cycle — of alternately contracting the muscles and then allowing them to relax — helps strengthen the muscles. Other positive side effects include increasing blood circulation to the area and reducing edema. The increased blood supply aids the natural healing process.

NMES units are not intended for pain relief. Your physician may prescribe a NMES device to help you regain your strength. Like a TENS unit, NMES units are small and easily portable, so you can use them at home or work.

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