TENS . transcutaneous electrical nerve stimulation

Transcutaneous Electrical Nerve Stimulation (TENS) is a method for pain relief. As the name suggests, it involves exposing the affected area to electrical current, achieved through a number of electrodes attached to the skin.

How TENS Works

This technique relieves pain mainly by stimulating the "pain gate mechanism." When tissues are damaged, the nerve fibers in the painful area become increasingly excited and sensitive, which leads to heightened pain perception in that region. However, in the same area, there are also a number of mechanoreceptors that respond to touch. Stimulating these nerve fibers can override pain signals from that area—this is known as the pain gate mechanism. These receptors can also be activated by electrical currents at certain frequencies (usually 90–130 Hz), as specified in the TENS device, which in turn leads to pain relief.

The use of TENS is a very common method for pain management. It is relatively inexpensive, easy to use, and its side effects are minimal compared to some oral painkillers. It is believed that this technique can relieve pain in about 70% of cases involving acute injuries.

Application of TENS

TENS devices can now be easily purchased from specialized retailers and are easy to apply, though some care is required. A small percentage of patients may be allergic to the conductive gel, the electrodes themselves, or the securing tape. Most modern devices come with self-adhesive electrodes that can be replaced after each use to reduce the risk of cross-infection if the device is shared. Because each patient’s symptoms differ, the device settings must be adjusted individually. It is always advised to follow the instructions provided with the device or seek professional guidance.

Typically, TENS devices have three main adjustable settings:

Frequency: Most devices operate in the range of 2–200 Hz. To stimulate mechanoreceptors, the frequency should usually be between 90 and 130 Hz.

Intensity: The current strength is also adjustable. Most devices can deliver between 80 and 100 mA.

Pulse width (duration): This controls how long the electrical current passes through the electrodes. Many practitioners place less emphasis on this compared to frequency and intensity, and some devices may not even have this adjustment.

Does TENS Cause Pain?

TENS devices should not cause discomfort, though a mild tingling sensation may be felt when the device is on. Since the optimal settings vary from person to person, careful adjustment is important to achieve the best effect.

Electrode Placement

As with the settings, electrode placement may vary depending on the individual’s symptoms. Typically, electrodes are placed on either side of the painful area, but variations are possible. Some practitioners focus on targeting a peripheral nerve or an acupuncture point.

Precautions

Caution is advised in the following situations:

If the skin area has abnormal sensation.

If the patient suffers from epilepsy.

When using TENS with children, since growth areas may be affected by electrical currents.

If the patient is pregnant, professional advice should be sought.

Contraindications – When NOT to Use TENS

TENS should not be used in the following cases:

Patients with pacemakers.

Patients allergic to electrodes, gel, or adhesive tape.

Patients with skin conditions such as eczema.

Patients with open wounds in the treatment area.

Patients with circulatory problems.

Application on the neck or upper chest area.