Transcutaneous electrical nerve stimulation or TENS for short, is a machine that transmits low voltage electrical impulses to the skin via surface electrodes. It reduces pain by transmitting electric current through the skin. It is best use when applied with a strong yet non-painful intensity. But how does it work? How does it do this?
TENS impulses interrupt the nociceptive or painful signals in the spinal cord as they travel from the painful tissue or organ. This reduces the overall level of pain that you feel. The electrodes are placed with the targeted areas in between them. You control the intensity and set it so that you feel a buzzing or prickling sensation.
Researchers explored the mechanism behind TENS units. They used functional MRI (fMRI) to view the activity or certain areas of the brain while they applied a TENS unit to a painful area. They found that certain areas of the brain were activated in people who were experiencing pain and applied TENS vs. those that had pain without applying TENS. The areas of the brain that were affected, included pain-inhibitory pathways of the brain to produce pain relief. So, essentially Tens helps to block the pain signal coming from the brain. Also, they found that by increasing the TENS intensity in a step wise or progressive fashion prevented temporal summation. This suggests that TENS application is effective for pain reduction.
So now we understand that TENS helps to reduce pain but how long does that last?
Another group of researchers wanted to see how long the effects of TENS last for. They had 2 groups; one who received TENS and the other with received “fake TENS”. They found that the group that received real TENS had pain improvement for at least 20-25 minutes after treatment in many areas of the brain. They also found that at 35 minutes after treatment some areas of the brain showed evidence of pain improvement compared to the group that received “fake TENS”.
All in all, TENS is a useful tool to help with temporary pain reduction. It does not however heal the pain generator or cause of the pain. It should be used in a program with other types of therapy to reduce pain and increase overall function. It is not effective as a sole type of treatment. For example TENS can be used to reduce low back pain temporarily so that your chiropractor can provide you with effective treatment to get ride of your back pain.