Spinal pain is currently one of the largest healthcare burdens in the United States. In 2013, it was estimated that roughly one in four Americans visited a physician for a diagnosis of back pain.[1] However, back pain is notoriously difficult to treat, particularly with pharmaceutical products— prescribing opioids, for example, increases the risk of future addiction and abuse.
Transcutaneous electrical nerve stimulators, or TENS, are used as a nonpharmacological treatment to provide symptom relief for spinal pain. The battery-operated device works by sending mild electrical impulses to the nerves at the site of injury via electrodes placed directly on the skin. They were first patented in the U.S. in 1974 and are available without prescription. Though TENS devices are generally safe, there is increased risk for adverse effects in patients with cancer or indwelling electrical devices, such as a pacemaker.
TENS therapy is often used to treat various types of spinal pain, including chronic low back pain and back pain arising from pregnancy. Research has suggested that the alleviation of pain associated with TENS likely depends on opioid pathways in the spine; for example, inhibition of GABAA receptors has been shown to reverse the effect of the therapy.[2],[3] To date, there remains a degree of controversy as to the mechanism by which TENS is able to provide analgesia for spinal pain. One theory most supported by research is that the electrical signaling from the TENS device can intercept or reduce transmission of pain signals going to the spinal cord and the brain. Studies indicate that the use of TENS to treat inflamed tissue inhibits primary hyperalgesia in a time-dependent manner.[4]
A recent meta-analysis published by Resende et al. suggests that TENS intervention improves pain, function, and disability during therapy.[5] However, the same study found that immediately after therapy and in the months following therapy, these measures did not differ significantly from control patients who did not undergo transcutaneous electrical nerve stimulator therapy.5 Therefore, research suggests that TENS may be best used as a treatment for temporary pain relief.
[1] Burden of Back Pain [Online]. BMUS: The Burden of Musculoskeletal Diseases in the United States. https://www.boneandjointburden.org/fourth-edition/iiac0/burden-back-pain [11 Oct. 2020].
[2] Hingne PM, Sluka KA. Differences in waveform characteristics have no effect on the anti-hyperalgesia produced by transcutaneous electrical nerve stimulation (TENS) in rats with joint inflammation. J Pain 2007;8:251–255. [PubMed: 17169615]
[3] Maeda Y, Lisi TL, Vance CG, et al. Release of GABA and activation of GABA(A) in the spinal cord mediates the effects of TENS in rats. Brain Res 2007;1136:43–50. [PubMed: 17234163]
[4] Vance CG, Radhakrishnan R, Skyba DA, et al. Transcutaneous electrical nerve stimulation at both high and low frequencies reduces primary hyperalgesia in rats with joint inflammation in a time-dependent manner. Phys Ther 2007;87:44–51. [PubMed: 17142641]
[5] Resende L, Merriwether E, Rampazo ÉP, Dailey D, Embree J, Deberg J, Liebano RE, Sluka KA. Meta-analysis of transcutaneous electrical nerve stimulation for relief of spinal pain. Eur J Pain. 2018 Apr;22(4):663-678. doi: 10.1002/ejp.1168. Epub 2017 Dec 27. PMID: 29282846.