Transcutaneous electrical nerve stimulation (TENS) is a non-invasive, drug-free technique used to reduce pain and relax muscles. It works by sending electrical impulses through the intact surface of the skin to activate underlying nerves. Patients can self-administer TENS and adjust the dose as needed, since there is no risk of overdose or drug interactions. TENS is a cost-effective alternative to long-term pharmacotherapy and can be purchased without a prescription in the UK.
However, it is recommended that a professional with experience in TENS principles supervise patients who are using it for the first time. A review found some evidence that people who receive TENS through acupuncture points may experience a reduction in pain. The effects of TENS usually appear quickly and are compensated, so patients are advised to administer it as needed and throughout the day. Maximum analgesic occurs when TENS generates strong but painless electrical paresthesia under the electrodes.
The position of the red and black cable usually has little effect in clinical practice, since biphasic waveforms with zero net current flow are often used in devices. A study found that TENS treatment provided temporary pain relief to people with fibromyalgia while the machine was in use. However, it's best to talk to a doctor before trying TENS, either as an alternative treatment or in combination with other pain management methods. Conventional TENS is first used, starting with a continuous pulse pattern and “mid-range” pulse frequencies (e.g., this inhibits the activity of second-order nociceptive transmission neurons in the central nervous system) and is achieved by increasing the amplitude of the TENS pulse to generate strong, comfortable and painless paresthesia under the electrodes.
People can carry a TENS unit in their pocket or clip it to a belt to ensure they have immediate access to a pain reliever throughout the day. The intention of conventional TENS is to selectively stimulate non-harmful afferents (A-beta) of large diameter and low threshold in pain-related dermatomes. Evidence from animal studies shows that TENS reduces continuous nociceptor cell activity and sensitization in the central nervous system when applied to somatic receptive fields and after spinal cord transection. TENS doesn't cure pain and often only provides short-term relief while using the TENS machine.
Initially, TENS was used to predict the success of dorsal spine stimulation implants until it was discovered that it could be used as a successful modality on its own. You can choose to buy your own TENS machine without consulting a doctor, but it's usually best to get a proper evaluation first, so that you can find out if a TENS machine is right for you and learn how to use it correctly.