title: The effects of transcranial direct current stimulation in patients with neuropathic pain from spinal cord injury.
abstract: OBJECTIVE
  Transcranial direct current stimulation (tDCS) has demonstrated efficacy for reducing neuropathic pain, but the respective mechanisms remain largely unknown. The current study tested the hypothesis that pain reduction with tDCS is associated with an increase in the peak frequency spectrum density in the theta-alpha range.
  
  
  METHODS
  Twenty patients with spinal cord injury and bilateral neuropathic pain received single sessions of both sham and anodal tDCS (2 mA) over the left primary motor area (M1) for 20 min. Treatment order was randomly assigned. Pre- to post-procedure changes in pain intensity and peak frequency of electroencephalogram spectral analysis were compared between treatment conditions.
  
  
  RESULTS
  The active treatment condition (anodal tDCS over M1) but not sham treatment resulted in significant decreases in pain intensity. In addition, consistent with the study hypothesis, peak theta-alpha frequency (PTAF) assessed from an electrode placed over the site of stimulation increased more from pre- to post-session among participants in the active tDCS condition, relative to those in the sham tDCS condition. Moreover, we found a significant association between a decrease in pain intensity and an increase in PTAF at the stimulation site.
  
  
  CONCLUSIONS
  The findings are consistent with the possibility that anodal tDCS over the left M1 may be effective, at least in part, because it results in an increase in M1 cortical excitability, perhaps due to a pain inhibitory effect of motor cortex stimulation that may influence the descending pain modulation system. Future research is needed to determine if there is a causal association between increased left anterior activity and pain reduction.
  
  
  CONCLUSIONS
  The results provide new findings regarding the effects of tDCS on neuropathic pain and brain oscillation changes.
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Niran
authors.initials: N
authors.lastname: Ngernyam
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, Seattle, USA.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Jensen
authors.affiliation: Department of Rehabilitation Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Preeda
authors.initials: P
authors.lastname: Arayawichanon
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Narong
authors.initials: N
authors.lastname: Auvichayapat
authors.affiliation: Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Somsak
authors.initials: S
authors.lastname: Tiamkao
authors.affiliation: Department of Electrical and Electronic Engineering, Faculty of Engineering, UbonRatchathani University, UbonRatchathani, 34190 Thailand.
authors.forename: Suparerk
authors.initials: S
authors.lastname: Janjarasjitt
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Wiyada
authors.initials: W
authors.lastname: Punjaruk
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Anuwat
authors.initials: A
authors.lastname: Amatachaya
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand.
authors.forename: Benchaporn
authors.initials: B
authors.lastname: Aree-uea
authors.affiliation: Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. Electronic address: aparad@kku.ac.th.
authors.forename: Paradee
authors.initials: P
authors.lastname: Auvichayapat
mesh_terms: D000328:Adult; D000368:Aged; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004569:Electroencephalography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009437:Neuralgia / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D065908:Transcranial Direct Current Stimulation / Q000379:methods*; D016896:Treatment Outcome
keywords: EEG spectral analysis; Electroencephalogram; Neuropathic pain; Spinal cord injury; Transcranial direct current stimulation