NEUROPHYSIOLOGICAL EVALUATION OF THE EFFECTS OF REPETITIVE PULSED RADIOFREQUENCY STIMULATION ON A MODEL OF NEUROPATHIC PAIN

Neuropathic pain remains a major clinical challenge, requiring effective and minimally invasive therapeutic strategies. Pulsed radiofrequency (PRF) is a minimally invasive electrical therapy used to manage refractory chronic pain. Routinely, it is delivered through percutaneous needle electrodes near target tissues. In this study an implantable device was implemented and tested to deliver PRF stimulation on the sciatic nerve in rats subjected to the spared nerve injury (SNI) model. Adult female rats underwent implantation of a cuff electrode around the sciatic nerve, connected to an electronic module placed subcutaneously. Then, SNI was induced by ligature of tibial and peroneal nerves, preserving sural and saphenous nerves. In one group (n=6) three PRF sessions (500 kHz bursts of 20 ms, 40 mA amplitude, at rate of 2 Hz, during 30 s) were delivered through the device on days 3, 10 and 17 post‑injury, whereas a second group (n=6) served as sham. Mechanical threshold (von Frey) and thermal thresholds (plantar test) were measured before and at time points postinjury. The results showed a marked decrease in both withdrawal thresholds after SNI, that was partially improved by PRF for 3 days, and maintained during the following 3 weeks, with significantly higher values than in the control group. Nerve conduction studies showed that PRF did not induce nerve damage. DRG and spinal cord were immunohistochemically analyzed to assess excitability and inflammatory responses. In conclusion, the newly implantable PRF system was effective in reducing hyperalgesia in this neuropathic pain model, inducing sustained analgesia with repeated treatments.