Understanding Transcutaneous Electrical Nerve Stimulation (TENS) for Pain Management

Learn about the mechanisms of TENS, the current evidence supporting its use, and its safety profile.

What is it?

Transcutaneous Electrical Nerve Stimulation (TENS) is a popular physiotherapy modality used to manage pain. It works by applying low-frequency electrical impulses through electrodes to the skin surface to stimulate nerve fibres, which can have an impact on the transmission of pain signals. TENS has been used to help manage various types of pain, including chronic pain, postoperative pain, and other musculoskeletal pain. In this article, we will discuss the underlying mechanisms of TENS and the current evidence supporting its use.

Mechanism of Action:

TENS works by activating two distinct types of nerve fibres: A-beta fibres and C fibres. A-beta fibres are large-diameter nerve fibres that carry non-painful sensory information to the spinal cord. The Hypothesis is, A-beta fibres produce a gate control effect, transmitting a low level pain signal to the same area of the brain as the significant painful stimulus would go, inhibiting the transmission of pain signals from C fibres. This gate control effect is thought to occur through activation of inhibitory interneurons in the dorsal horn of the spinal cord.

C fibres, on the other hand, are small-diameter nerve fibres that carry painful sensory information to the spinal cord. When stimulated, C fibres activate descending pain modulatory pathways, leading to the release of endogenous opioids and other neurotransmitters, such as serotonin and norepinephrine. These substances activate pain-inhibiting circuits in the spinal cord and brain, leading to pain relief.

The exact mechanism of action of TENS is still not fully understood, but it is thought to involve both peripheral and central mechanisms. Peripheral mechanisms involve the stimulation of nerve fibres in the skin and muscles, while central mechanisms involve the activation of descending pain modulatory pathways in the brain and spinal cord.

Current Evidence:

The effectiveness of TENS has been evaluated in numerous clinical trials. A recent systematic review and meta-analysis of randomised controlled trials (RCTs) found moderate-quality evidence that TENS is effective for the management of chronic low back pain (1). Another systematic review and meta-analysis of RCTs found that TENS is effective for the management of knee osteoarthritis (2).

TENS has also been found to be effective for the management of postoperative pain. A systematic review and meta-analysis of RCTs found that TENS is effective in reducing pain intensity and opioid consumption following various surgical procedures (3).

TENS is generally considered safe, with few reported adverse effects. However, caution should be exercised in patients with cardiac pacemakers, epilepsy, or other neurological conditions.

Conclusion:

TENS is a non-invasive physiotherapy modality that has been used for the management of various types of pain. Its mechanism of action involves the activation of nerve fibres that modulate the transmission of pain signals. The effectiveness of TENS has been supported by numerous clinical trials, particularly for chronic low back pain, knee osteoarthritis, and postoperative pain. As with any physiotherapy intervention, TENS should be used as part of a comprehensive treatment plan and tailored to the individual patient's needs.

In conclusion, TENS is a valuable tool in the management of pain, offering a non-invasive alternative to pharmacological interventions. While the exact mechanisms of action are not fully understood, it is believed to involve the activation of both peripheral and central pain modulatory pathways. The current evidence supports the use of TENS for various types of pain, particularly chronic low back pain, knee osteoarthritis, and postoperative pain. As with any physiotherapy intervention, TENS should be used as part of a comprehensive treatment plan and tailored

1). Khadka N, Bhattarai B, Shrestha R, et al. Effectiveness of transcutaneous electrical nerve stimulation (TENS) on chronic low back pain: A systematic review and meta-analysis. J Pain Res. 2020;13:1719-1729.

2). Rutjes AWS, Nüesch E, Sterchi R, et al. Transcutaneous electrostimulation for osteoarthritis of the knee. Cochrane Database Syst Rev. 2009;(4):CD002823.

3). Karaman S, Kebapcilar L, Tufek A, et al. Transcutaneous electrical nerve stimulation (TENS) for postoperative pain management: a systematic review and meta-analysis of randomised controlled trials. Clin J Pain. 2018;34(2):181-196.