title: The effects of transcranial direct current stimulation with visual illusion in neuropathic pain due to spinal cord injury: an evoked potentials and quantitative thermal testing study.
abstract: BACKGROUND
  Neuropathic pain (NP) is common in spinal cord injury (SCI) patients. One of its manifestations is a lowering of pain perception threshold in quantitative thermal testing (QTT) in dermatomes rostral to the injury level. Transcranial direct current stimulation (tDCS) combined with visual illusion (VI) improves pain in SCI patients. We studied whether pain relief with tDCS + VI intervention is accompanied by a change in contact heat- evoked potentials (CHEPs) or in QTT.
  
  
  METHODS
  We examined 18 patients with SCI and NP before and after 2 weeks of daily tDCS + VI intervention. Twenty SCI patients without NP and 14 healthy subjects served as controls. We assessed NP intensity using a numerical rating scale (NRS) and determined heat and pain thresholds with thermal probes. CHEPs were recorded to stimuli applied at C4 level, and subjects rated their perception of evoked pain using NRS during CHEPs.
  
  
  RESULTS
  Thirteen patients reported a mean decrease of 50% in the NRS for NP after tDCS + VI. Evoked pain perception was significantly higher than in the other two groups, and reduced significantly together with CHEPs amplitude after tDCS + VI with respect to baseline. Pain perception threshold was significantly lower than in the other two groups before tDCS + VI intervention, and increased significantly afterwards.
  
  
  CONCLUSIONS
  Two weeks of tDCS + VI induced significant changes in CHEPs, evoked pain and heat pain threshold in SCI patients with NP. These neurophysiological tests might be objective biomarkers of treatment effects for NP in patients with SCI.
authors.affiliation: Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain. hkumru@guttmann.com
authors.forename: H
authors.initials: H
authors.lastname: Kumru
authors.forename: D
authors.initials: D
authors.lastname: Soler
authors.forename: J
authors.initials: J
authors.lastname: Vidal
authors.forename: X
authors.initials: X
authors.lastname: Navarro
authors.forename: J M
authors.initials: JM
authors.lastname: Tormos
authors.forename: A
authors.initials: A
authors.lastname: Pascual-Leone
authors.forename: J
authors.initials: J
authors.lastname: Valls-Sole
mesh_terms: D000328:Adult; D000368:Aged; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D017288:Pain Threshold / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods*; D012684:Sensory Thresholds / Q000502:physiology; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*