title: tDCS modulates cortical nociceptive processing but has little to no impact on pain perception.
abstract: Transcranial direct current stimulation (tDCS) effectively modulates cortical excitability. Several studies suggest clinical efficacy in chronic pain syndromes. However, little is known regarding its effects on cortical pain processing. In this double-blind, randomized, cross-over, sham controlled study, we examined the effects of anodal, cathodal, and sham stimulation of the left motor cortex in 16 healthy volunteers using functional imaging during an acute heat pain paradigm as well as pain thresholds, pain intensity ratings, and quantitative sensory testing. tDCS was applied at 1 mA for 15 minutes. Neither cathodal nor anodal tDCS significantly changed brain activation in response to nociceptive stimulation when compared with sham stimulation. However, contrasting the interaction of stimulation modes (anodal/cathodal) resulted in a significant decrease of activation in the hypothalamus, inferior parietal cortex, inferior parietal lobule, anterior insula, and precentral gyrus, contralateral to the stimulation site after anodal stimulation, which showed the opposite behavior after cathodal stimulation. Pain ratings and heat hyperalgesia showed only a subclinical pain reduction after anodal tDCS. Larger-scale clinical trials using higher tDCS intensities or longer durations are necessary to assess the neurophysiological effect and subsequently the therapeutic potential of tDCS.
authors.affiliation: Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Kristin
authors.initials: K
authors.lastname: Ihle
authors.affiliation: Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Rea
authors.initials: R
authors.lastname: Rodriguez-Raecke
authors.affiliation: Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Luedtke
authors.affiliation: Department of Systems Neuroscience, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany. Electronic address: a.may@uke.de.
authors.forename: Arne
authors.initials: A
authors.lastname: May
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D059225:Nociception / Q000502:physiology*; D058748:Pain Perception / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Antinociceptive system; Functional imaging; Neuromodulation; Nociception; Pain; QST; Quantitative sensory testing; Transcranial direct current stimulation; fMRI; tDCS