title: Facilitation of A[delta]-fiber-mediated acute pain by repetitive transcranial magnetic stimulation.
abstract: BACKGROUND
  Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex modulates acute and chronic pain perception. The authors previously showed that rTMS over the primary motor cortex (M1) inhibited capsaicin-induced acute pain ascending through C-fibers.
  
  
  OBJECTIVE
  To investigate the effects of 1-Hz rTMS over M1 on acute experimentally induced pain mediated by Adelta-fibers (i.e., another type of acute pain).
  
  
  METHODS
  The authors examined whether rTMS over M1 affected laser evoked potentials (LEPs) in 13 normal subjects using thulium: yttrium-aluminum-garnet laser stimulation. Subjective pain-rating scores and LEPs obtained under three different conditions--rTMS, realistic sham stimulation, and a control condition with no stimulation--were compared.
  
  
  RESULTS
  The authors found that 1-Hz rTMS over M1 significantly aggravated the subjective pain and enhanced the N2-P2 amplitudes compared with the sham or control sessions. Because the pain-rating scores and the N2-P2 amplitudes correlated positively, the N2-P2 amplitudes in the present study can be regarded as the cortical correlate of subjective pain.
  
  
  CONCLUSIONS
  Together with the authors' previous study on C-fiber pain, this facilitatory effect of repetitive transcranial magnetic stimulation on Adelta-fiber-mediated further strengthens the notion of a relationship between repetitive transcranial magnetic stimulation over M1 and pain perception.
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan. ytamura@nips.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Tamura
authors.forename: M
authors.initials: M
authors.lastname: Hoshiyama
authors.forename: K
authors.initials: K
authors.lastname: Inui
authors.forename: H
authors.initials: H
authors.lastname: Nakata
authors.forename: Y
authors.initials: Y
authors.lastname: Qiu
authors.forename: Y
authors.initials: Y
authors.lastname: Ugawa
authors.forename: K
authors.initials: K
authors.lastname: Inoue
authors.forename: R
authors.initials: R
authors.lastname: Kakigi
mesh_terms: D000208:Acute Disease; D000328:Adult; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D007834:Lasers; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D009412:Nerve Fibers / Q000502:physiology*; D010146:Pain / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement; D050781:Transcranial Magnetic Stimulation