Randomized Double-Blind Sham-Controlled Crossover Study of Short-Term Effect of Percutaneous Electrical Nerve Stimulation in Neuropathic Pain

Background. Percutaneous electrical nerve stimulation (PENS) is an electrical neuromodulation technique that has shown its therapeutic potential in various chronic pain conditions over the past few years, but well-blinded controlled studies are lacking. Patients and Methods. A randomized double-blind sham-controlled crossover trial on 31 patients with chronic pain with surface hyperalgesia to investigate the efficacy of PENS. Results. For the active PENS therapies, the median numerical rating scale (NRS) for pain changed from 7.5 (standard deviation [SD] +/- 1) (range 6-10) before therapy to 0.5 (range 0-8.5) after therapy (Z = -4.206, P < 0.0005 [two-tailed]). The mean pain pressure threshold (PPT) measured with the von Frey aesthesiometer changed from 202 gm (SD +/- 137 gm) (range 55-800 gm) before therapy to 626 gm (SD +/- 228 gm) (range 45-800 gm) after therapy (Z = -4.373, P < 0.0005 [two-tailed]). There was a statistically significant difference between the changes in NRS for the active (3.9 [+/- 3.2] [0-8]) compared with the sham (0.1 [+/- 0.4] [0-1.5]) therapies, U = 40, Z = -3.484, P < 0.0001 (two-tailed). There was a statistically significant difference between the changes in PPT for the active (310 gm [+/- 267 gm] [0-670 gm]) compared with the sham (8 gm [+/- 4 gm] [0-15 gm]) therapies, U = 48.5, Z = -2.699, P = 0.007 (two-tailed). Conclusion. PENS therapy appears to be effective in providing short-term pain relief in chronic pain conditions. Studies, involving larger sample sizes and longer follow-up are recommended.