title: Lidocaine patch (5%) in treatment of persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial.
abstract: BACKGROUND
  Evidence-based pharmacological treatment options for patients with persistent inguinal postherniorrhaphy pain are lacking.
  
  
  METHODS
  Twenty-one male patients, with severe, unilateral, persistent inguinal postherniorrhaphy pain, participated in a randomized, double-blind, placebo-controlled crossover trial, receiving lidocaine patch (5%) and placebo patch treatments in periods of 14 days separated by a 14-day wash-out period. Pain intensities (at rest, during movement, and pressure evoked [Numerical Rating Scale]) were assessed before treatment and on the last 3 days of each treatment period. Patients were a priori divided into two subgroups based on quantitative sensory testing (+/- thermal "hyposensitivity"). Skin biopsies for intraepidermal nerve fiber density assessment were taken at baseline, and quantitative sensory testing was performed before and after each treatment period. The primary outcome was change in pain intensity assessed as the difference in summed pain intensity differences between lidocaine and placebo patch treatments.
  
  
  RESULTS
  There was no difference in summed pain intensity differences between lidocaine and placebo patch treatments in all patients (mean difference 6.2% [95% CI = -6.6 to 18.9%]; P = 0.33) or in the two subgroups (+/- thermal "hyposensitivity"). The quantitative sensory testing (n = 21) demonstrated an increased pressure pain thresholds after lidocaine compared with placebo patch treatment. Baseline intraepidermal nerve fiber density (n = 21) was lower on the pain side compared with the nonpain side (-3.8 fibers per millimeter [95% CI = -6.1 to -1.4]; P = 0.003). One patient developed mild erythema in the groin during both treatments.
  
  
  CONCLUSIONS
  Lidocaine patch treatment did not reduce combined resting and dynamic pain ratings compared with placebo in patients with severe, persistent inguinal postherniorrhaphy pain.
authors.affiliation: * Research Assistant, Multidisciplinary Pain Centre 7612, Rigshospitalet, Copenhagen University, Copenhagen, Denmark, and Section of Surgical Pathophysiology 4074, Rigshospitalet, Copenhagen University. † Research Nurse, # Associate Professor, Multidisciplinary Pain Centre 7612, Rigshospitalet, Copenhagen University. ‡ Assistant Professor, § Professor, Department of Neurology, University Hospital of Würzburg, Würzburg, Germany. ‖ Professor, Section of Surgical Pathophysiology 4074, Rigshospitalet, Copenhagen University.
authors.forename: Joakim M
authors.initials: JM
authors.lastname: Bischoff
authors.forename: Marian
authors.initials: M
authors.lastname: Petersen
authors.forename: Nurcan
authors.initials: N
authors.lastname: Uçeyler
authors.forename: Claudia
authors.initials: C
authors.lastname: Sommer
authors.forename: Henrik
authors.initials: H
authors.lastname: Kehlet
authors.forename: Mads U
authors.initials: MU
authors.lastname: Werner
mesh_terms: D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D023381:Endpoint Determination; D005260:Female; D006552:Hernia, Inguinal / Q000601:surgery*; D059685:Herniorrhaphy / Q000009:adverse effects*; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology; D010147:Pain Measurement / Q000187:drug effects; D010149:Postoperative Pain / Q000188:drug therapy*; D017060:Patient Satisfaction; D012684:Sensory Thresholds / Q000187:drug effects; D012867:Skin / Q000294:innervation / Q000473:pathology; D012893:Sleep Wake Disorders / Q000139:chemically induced; D057968:Transdermal Patch
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine