Comparison of percutaneous electrical nerve stimulation with transcutaneous electrical nerve stimulation for long-term pain relief in patients with chronic low back pain

The long-term effect of percutaneous electrical nerve stimulation (PENS) on chronic low back pain (LBP) is unclear. We evaluated the number of sessions for which PENS should be performed to alleviate chronic LBP and how long analgesia is sustained. Patients underwent treatment on a twice-weekly schedule for 8 wk. Group A (n = 18) received PENS for 8 wk, group B (n = 17) received PENS for the first 4 wk and transcutaneous electrical nerve stimulation (TENS) for the second 4 wk, and group C (n = 18) received TENS for 8 wk. Pain level, degree of physical impairment, and the daily intake of nonsteroidal antiinflammatory drugs (NSAIDs) were assessed before the first treatment, 3 days after Week 2, Week 4, and Week 8 treatments, and at 1 and 2 mo after the sessions. During PENS therapy, the pain level decreased significantly from Week 2 in Groups A and B (P < 0.05 or 0.01), and physical impairment and required NSAIDs decreased significantly from Week 4 (P < 0.05 or 0.01) in Group A but only at Week 4 in Group B (P < 0.05 or 0.01). These effects were sustained until 1-mo follow-up (P < 0.01) in Group A but not in Group B; these effects were not observed at 2-mo follow-up even in Group A. In Group C, pain level decreased significantly only at Week 8 (P < 0.05). Our results indicate that repeated PENS is more effective than TENS for chronic LBP but must be continued to sustain the analgesic effect.