Effect of Transcutaneous Electrical Nerve Stimulation on Postoperative Pain after Inguinal Hernia Repair: A Randomized Placebo-Controlled Trial

Objective: Transcutaneous electrical nerve stimulation (TENS) is widely used for pain management in various clinical conditions. In this prospective, randomized, double-blind, placebo-controlled study, we investigated the effect of TENS on postoperative pain, analgesic requirements and serum cortisol level (SCL) after inguinal hernia repair. Materials and Methods: Sixty-seven patients, who underwent a standard surgical hernia repair using the Lichtenstein principles with a wound infiltration anesthetic technique, were randomly chosen to receive either active TENS (conventional TENS at 100 Hz, with a pulse width of 120 microseconds and a perceptible tingling sensation) or placebo TENS treatment. Both active and placebo TENS treatments were applied for 30 minutes, twice daily for 5 consecutive days using two electrodes placed parallel to the incision. Pain intensity was assessed using the visual analogue scale (VAS) and SCL measured on 5 consecutive postoperative days (PODs), respectively. Follow-up assessment of pain intensity was performed at 30 days postoperatively. Results: Baseline parameters were similar between the groups. Pain intensity in the active TENS group significantly decreased at POD1 (p<0.04), POD2 (p<0.027), POD3 (p<0.026), POD4 (p<0.0006), and POD5 (p<0.0006), and after one month compared with the placebo group. Postoperative SCL was decreased in the active TENS group compared with placebo TENS (p<0.05). Conclusion: Our results indicate that TENS is beneficial for postoperative pain relief following inguinal hernia repair. No side effects were observed, and its pain-reducing effect lasted for one month postoperatively. Consequently, the routine use of TENS after inguinal hernia repair is recommended for its short-and long-term effectiveness for decreasing pain, analgesic requirement and SCL. Turk J Phys Med Rehab 2010;56:170-6.