title: Effects of tDCS-induced motor cortex modulation on pain in HTLV-1: a blind randomized clinical trial.
abstract: OBJECTIVE
  We aimed to evaluate the effects of transcranial direct current stimulation (tDCS) on chronic pain in human T-lymphotropic virus type I-infected patients.
  
  
  METHODS
  This is a sham-controlled randomized clinical trial. Twenty participants were randomized to receive active or sham anodal tDCS over the primary motor cortex (M1), with 2 mA, 25 cm electrodes, for 20 minutes on 5 consecutive days. Pain intensity was measured at baseline and after each day of treatment using a Visual Analog Scale. Associated factors such as pain components description, pressure pain threshold, and Timed Up and Go task were also assessed.
  
  
  RESULTS
  Mild adverse events were reported by 100% of patients in the tDCS group and 90% in the sham group. Comparison of daily Visual Analog Scale pain scores from both groups demonstrated a significant effect for the factor Time (P<0.001), but not for Group (P=0.13) or Time×Group interaction (P=0.06). There were 8 (80%) responders (reduction of 50% or more in pain intensity) in the tDCS group and 3 (30%) in the sham group (P=0.03). Both groups demonstrated improvements for most associated factors evaluated. However, there was no difference in between-groups comparison analyses.
  
  
  CONCLUSIONS
  The analysis of the main outcomes in this study did not demonstrate a significant advantage of anodal tDCS applied to M1 in patients with human T-lymphotropic virus type I and chronic pain in comparison with sham tDCS, although secondary analysis suggests some superiority of active tDCS over sham. The large placebo effect observed in this study may explain the small differences between sham versus active tDCS.
authors.affiliation: *Bahian School of Medicine and Public Health †Laboratory of Functional Electrostimulation, Federal University of Bahia, Salvador, Bahia ‡Department of Neuroscience and Behavior, Institute of Psychiatry, University of São Paulo, São Paulo, Brazil §Laboratory of Neuromodulation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA.
authors.forename: Giórgio
authors.initials: G
authors.lastname: Souto
authors.forename: Igor C
authors.initials: IC
authors.lastname: Borges
authors.forename: Bruno T
authors.initials: BT
authors.lastname: Goes
authors.forename: Mariana E
authors.initials: ME
authors.lastname: de Mendonça
authors.forename: Roberta G
authors.initials: RG
authors.lastname: Gonçalves
authors.forename: Lucas B
authors.initials: LB
authors.lastname: Garcia
authors.forename: Katia N
authors.initials: KN
authors.lastname: Sá
authors.forename: Márcio R
authors.initials: MR
authors.lastname: Coutinho
authors.forename: Bernardo
authors.initials: B
authors.lastname: Galvão-Castro
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
authors.forename: Abrahão F
authors.initials: AF
authors.lastname: Baptista
mesh_terms: D059350:Chronic Pain / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D015490:HTLV-I Infections / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D009437:Neuralgia / Q000503:physiopathology / Q000628:therapy; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement; D017288:Pain Threshold; D011312:Pressure; D016037:Single-Blind Method; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects / Q000379:methods*