A Transcutaneous Electrical Nerve Stimulation (TENS) unit is a small, battery-powered device that delivers low-voltage electrical currents through the skin. Its primary purpose is to provide non-invasive pain relief by stimulating nerves and blocking pain signals or promoting the release of endorphins. Proper electrode placement is important for effective and safe use.
General Principles for Electrode Placement
Effective TENS therapy requires proper preparation. Before applying electrodes, ensure skin is clean, dry, and free of oils, lotions, or hair for good adhesion and conductivity. Press electrodes firmly against the skin for consistent electrical stimulation.
The size and shape of the electrodes should correspond to the treatment area, with smaller pads suitable for localized pain and larger pads for broader areas. When placing electrodes, they should be positioned at least one inch apart and never touch each other, as this can cause discomfort or reduce effectiveness. Typically, electrodes are placed around the perimeter of the painful area to allow the current to flow through the affected nerve fibers.
It is important to avoid placing electrodes directly over joints, bony prominences, or open wounds, as this can lead to discomfort, reduced effectiveness, or skin irritation. Sensitive areas such as the eyes, mouth, front or sides of the neck, head, and directly over the heart should also be avoided. Additionally, electrodes should not be placed on areas with impaired sensation, as this could increase the risk of burns due to a lack of feedback regarding intensity.
Electrode Placement for Common Pain Areas
For back pain, electrodes are commonly placed on either side of the spine or surrounding the area of discomfort, taking care to avoid direct placement on the spinal column itself. For lower back pain, pads can be positioned on either side of the painful area, or one set can be placed above and another below the affected region. If pain is centralized, a square formation around the area can be effective.
When addressing neck and shoulder pain, electrodes can be placed on either side of the neck at the base of the skull or about two inches below. For shoulder pain, pads might be positioned on the front and back of the shoulder or on muscles close to the neck and shoulder blade, ensuring they are not directly over bone.
For knee pain, electrodes are typically placed around the knee joint rather than directly on the kneecap. Common approaches include positioning pads above and below the knee, or on either side of the knee to surround the painful area. This targets the muscles surrounding the joint, such as the quadriceps and hamstrings, for more comprehensive relief.
In cases of elbow or wrist pain, electrodes are generally placed above and below the painful area or on either side of it. For wrist pain, one pad can be placed directly over the pain, with another pad positioned either above or below it. Alternatively, pads can be staggered along the forearm, with one near the wrist and another closer to the elbow joint. For general limb pain, such as in the thigh or calf, electrodes are typically placed on either side of the muscle, or at the top and bottom of the painful region, following the path of the nerves or muscles.
Safe Use and Important Considerations
TENS therapy is generally contraindicated for individuals who are pregnant, have a pacemaker or other implanted electronic devices, or have epilepsy. It should also not be used over areas with active cancer, deep vein thrombosis, bleeding disorders, or over infected tissues, damaged skin, or varicose veins.
TENS units can be used for 20-30 minutes per session, multiple times a day as needed. While relief duration varies, allow for rest periods between sessions to prevent tolerance and minimize skin irritation.
Skin irritation, such as redness or itching, can occur from electrode use. To minimize this, ensure proper skin preparation, regularly check the skin under electrodes, and rotate placement slightly. Clean electrodes with mild soap and water after use, rinse thoroughly, and air dry. Store them in resealable bags in a cool, dry place to maintain adhesive properties and prolong their life.
Before initiating TENS therapy, consulting a healthcare professional is important. They can provide personalized advice on electrode placement and appropriate settings, ensuring the therapy is safe and effective.