title: Hypoalgesic effect of the transcutaneous electrical nerve stimulation following inguinal herniorrhaphy: a randomized, controlled trial.
abstract: We investigated the effect of transcutaneous electrical nerve stimulation (TENS) for inguinal herniorrhaphy postoperative pain control in a prospective, randomized, double-blinded, placebo-controlled study. Forty patients undergoing unilateral inguinal herniorrhaphy with an epidural anesthetic technique were randomly allocated to receive either active TENS or placebo TENS. Postoperative pain was evaluated using a standard 10-point numeric rating scale (NRS). Analgesic requirements were also recorded. TENS (100 Hz, strong but comfortable sensory intensity) was applied for 30 minutes through 4 electrodes placed around the incision twice, 2 and 4 hours after surgery. Pain was assessed before and after each application of TENS and 8 and 24 hours after surgery. In the group treated with active TENS, pain intensity was significantly lower 2 hours (P = .028), 4 hours (P = .022), 8 hours (P = .006), and 24 hours (P = .001) after the surgery when compared with the group that received placebo TENS. Active TENS also decreased analgesic requirements in the postoperative period when compared with placebo TENS (P = .001). TENS is thus beneficial for postoperative pain relief after inguinal herniorrhaphy; it has no observable side effects, and the pain-reducing effect continued for at least 24 hours. Consequently, the routine use of TENS after inguinal herniorrhaphy is recommended.
  
  
  CONCLUSIONS
  This study presents the hypoalgesic effect of high-frequency TENS for postoperative pain after inguinal herniorrhaphy. This may reinforce findings from basic science showing an opioid-like effect provided by TENS, given that high-frequency TENS has been shown to activate delta-opioid receptors.
authors.affiliation: Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, Iowa City, Iowa 52242, USA. josimari-desantana@uiowa.edu
authors.forename: Josimari M
authors.initials: JM
authors.lastname: DeSantana
authors.forename: Valter J
authors.initials: VJ
authors.lastname: Santana-Filho
authors.forename: Danilo Ribeiro
authors.initials: DR
authors.lastname: Guerra
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
authors.forename: Ronaldo Q
authors.initials: RQ
authors.lastname: Gurgel
authors.forename: Walderi M
authors.initials: WM
authors.lastname: da Silva
mesh_terms: D015669:Acupuncture Points; D000328:Adult; D016058:Analgesia, Patient-Controlled / Q000379:methods; D004311:Double-Blind Method; D004599:Electric Stimulation Therapy / Q000009:adverse effects / Q000379:methods*; D006552:Hernia, Inguinal / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D011446:Prospective Studies; D004561:Transcutaneous Electric Nerve Stimulation / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome