title: Efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia.
abstract: Provoked vestibulodynia is a highly prevalent condition characterized by acute recurrent pain located at the vaginal entrance in response to pressure application or attempted vaginal penetration. Despite a wide variety of treatments offered to women with provoked vestibulodynia, a high proportion of women are refractory to conventional treatment. Transcranial direct-current stimulation is a noninvasive brain stimulation technique that has been shown effective for improving various chronic pain conditions. Growing evidence suggests that the central nervous system could play a key role in provoked vestibulodynia. Targeting the central nervous system could therefore be a promising treatment for women with provoked vestibulodynia.
  
  
  
  The purpose of this study was to evaluate and compare the efficacy of active and sham transcranial direct-current stimulation in reducing pain intensity during intercourse in patients with provoked vestibulodynia.
  
  
  
  We conducted a triple-blind, parallel-group, randomized controlled trial. Women aged 17-45 years diagnosed with provoked vestibulodynia by a gynecologist using a validated protocol were randomized to 10 sessions of either active transcranial direct-current stimulation (intensity = 2 mA) or 10 sessions of sham transcranial direct-current stimulation, over a 2-week period. Both active and sham transcranial direct-current stimulation were applied for 20 minutes, with the anode positioned over the primary motor cortex, and the cathode over the contralateral supraorbital area. Outcome measures were collected at baseline, 2 weeks after treatment, and at 3-month follow-up by an evaluator blinded to group assignment. The primary objective was to assess pain intensity during intercourse, using a numerical rating scale. Secondary outcomes focused on sexual function and distress, vestibular sensitivity, psychological distress, treatment satisfaction, and patient impression of change. Statistical analyses were conducted on the intention-to-treat basis, and treatment effects were evaluated using a mixed linear model for repeated measures.
  
  
  
  A total of 40 patients were randomly assigned to receive either active (n = 20) or sham (n = 20) transcranial direct-current stimulation treatments from November 2014 through February 2016. Baseline characteristics were similar between the active and sham transcranial direct-current stimulation groups. In full compliance with the study protocol, every participant followed all courses of the study treatment, including assessments at 2-week and 3-month follow-up. Pain during sexual intercourse was not significantly different between active and sham treatment groups 2 weeks after treatment (P = .84) and at follow-up (P = .09). Mean baseline and 2-week assessment pain intensity were, respectively, 6.8 (95% confidence interval, 5.9-7.7) and 5.6 (95% confidence interval, 4.7-6.5) for active transcranial direct-current stimulation (P = .03) vs 7.5 (95% confidence interval, 6.6-8.4) and 5.7 (95% confidence interval, 4.8-6.6) for sham transcranial direct-current stimulation (P = .001). Nonsignificant differences between the 2 groups were also found in their sexual function and distress after treatment (P > .20) and at follow-up (P > .10). Overall, at 2-week assessment 68% assigned to active transcranial direct-current stimulation reported being very much, much, or slightly improved compared to 65% assigned to sham transcranial direct-current stimulation (P = .82), and still comparable at follow-up: 42% vs 65%, respectively (P = .15).
  
  
  
  Findings suggest that active transcranial direct-current stimulation is not more effective than sham transcranial direct-current stimulation for reducing pain in women with provoked vestibulodynia. Likewise, no significant effects were found on sexual function, vestibular sensitivity, or psychological distress.
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Annie
authors.initials: A
authors.lastname: Morin
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Léonard
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Gougeon
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Cyr
authors.affiliation: Department of Obstetrics Gynecology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Guy
authors.initials: G
authors.lastname: Waddell
authors.affiliation: Department of Obstetrics Gynecology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Yves-André
authors.initials: YA
authors.lastname: Bureau
authors.affiliation: Department of Obstetrics Gynecology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Girard
authors.affiliation: School of Rehabilitation, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada. Electronic address: melanie.m.morin@usherbrooke.ca.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Morin
mesh_terms: D000293:Adolescent; D000328:Adult; D003075:Coitus / Q000502:physiology* / Q000523:psychology; D005260:Female; D006801:Humans; D008875:Middle Aged; D010147:Pain Measurement; D013315:Stress, Psychological / Q000523:psychology; D065908:Transcranial Direct Current Stimulation; D016896:Treatment Outcome; D056650:Vulvodynia / Q000523:psychology / Q000628:therapy*; D055815:Young Adult
keywords: chronic pain; dyspareunia; pain thresholds; provoked vestibulodynia; psychological distress; randomized controlled trial; sexual dysfunction; transcranial direct-current stimulation