title: Modulation of visual evoked potentials by high-frequency repetitive transcranial magnetic stimulation in migraineurs.
abstract: OBJECTIVE
  High-frequency repetitive transcranial magnetic stimulation (rTMS) modulates cortical excitability. We investigated its effect on visual evoked potentials (VEPs) in migraine.
  
  
  METHODS
  Thirty-two headache-free controls (CO), 25 interictal (MINT) and 7 preictal migraineurs (MPRE) remained after exclusions. VEPs to 8' and 65' checks were averaged in six blocks of 100 single responses. VEPs were recorded before, directly after and 25min after 10Hz rTMS. The study was blinded for diagnosis during recording and for diagnosis and block number during analysis. First block amplitudes and habituation (linear amplitude change over blocks) were analysed with repeated measures ANOVA.
  
  
  RESULTS
  With 65' checks, N70-P100 habituation was reduced in MINT compared to CO after rTMS (p=0.013). With 8' checks, habituation was reduced in MPRE compared to MINT and CO after rTMS (p<0.016). No effects of rTMS on first block amplitudes were found.
  
  
  CONCLUSIONS
  RTMS reduced habituation only in migraineurs, indicating increased responsivity to rTMS. The magnocellular visual subsystem may be affected interictally, while the parvocellular system may only be affected preictally.
  
  
  CONCLUSIONS
  Migraineurs may have increased responsiveness to rTMS because of a cortical dysfunction that changes before a migraine attack.
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway. Electronic address: pmomland@gmail.com.
authors.forename: Petter M
authors.initials: PM
authors.lastname: Omland
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway.
authors.forename: Martin
authors.initials: M
authors.lastname: Uglem
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Morten
authors.initials: M
authors.lastname: Engstrøm
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Mattias
authors.initials: M
authors.lastname: Linde
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Knut
authors.initials: K
authors.lastname: Hagen
authors.affiliation: Norwegian University of Science and Technology, Department of Neuroscience, Trondheim, Norway; St. Olavs Hospital, Department of Neurology and Clinical Neurophysiology, Trondheim, Norway.
authors.forename: Trond
authors.initials: T
authors.lastname: Sand
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002540:Cerebral Cortex; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006801:Humans; D008297:Male; D008881:Migraine Disorders / Q000503:physiopathology*; D010719:Phosphenes / Q000502:physiology; D016037:Single-Blind Method; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014793:Visual Cortex / Q000503:physiopathology*; D055815:Young Adult
keywords: Habituation; Migraine; Phosphene thresholds; Repetitive transcranial magnetic stimulation; Visual evoked potentials