Sensory and motor effects produced by LTP-inducing nerve stimulation in human patients with pain

Somatosensory plasticity can be induced in both animals and humans by electrical stimulation of skin afferents. Notably, in a previous study we demonstrated that percutaneous peripheral nerve stimulation (pPNS) could potentiate non-nociceptive circuits, producing regional hypoalgesia in healthy humans. Intending to translate this finding into a therapeutic tool, we conducted a clinical trial in pain-suffering patients to investigate the effects of two pPNS protocols designed to potentiate non nociceptive circuits. Forty-five patients with neck pain were assigned to one out of three protocols. The first protocol involved low intensity percutaneous High-Frequency Stimulation (pHFS) consisting of 100Hz, 5 second trains, while the second protocol employed motor-threshold intensity percutaneous Theta-Burst Stimulation (pTBS) comprising 5Hz trains of 100Hz pulses. As a control, we used Transcutaneous Electrical Nerve Stimulation (TENS) at 100 Hz, the current standard in therapeutic electrical stimulation for pain alleviation. Although all protocols produced an immediate relief in the pain perceived during neck movement, only the LTP-inducing protocols (pHFS and pTBS) produced a long-lasting pain reduction along the week following stimulation. In addition, pHFS produced hypoalgesia when subjects were at rest, whereas pTBS and TENS led to increased strength immediately after treatment. This study demonstrates the clinical efficacy for pain reduction of LTP-inducing pPNS protocols, surpassing the current reference treatment. These findings contribute to understanding the sensory and motor effects of peripheral nerve stimulation and allow us to advance in its clinical optimization, transferring basic neuroscience into healthcare practice.