Modulation of visual evoked potentials by high-frequency repetitive transcranial magnetic stimulation in migraineurs

• High-frequency repetitive transcranial magnetic stimulation (rTMS) reduced visual evoked potential (VEP) habituation in migraineurs, indicating an increased cortical responsiveness to rTMS.
• The increased responsiveness to rTMS in migraineurs may be caused by a cortical dysfunction that changes in the period before a migraine attack.
• High-frequency rTMS stimulation did not restore VEPs to normal in migraineurs.

ObjectiveHigh-frequency repetitive transcranial magnetic stimulation (rTMS) modulates cortical excitability. We investigated its effect on visual evoked potentials (VEPs) in migraine.MethodsThirty-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 25 min after 10 Hz 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.ResultsWith 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.ConclusionRTMS 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.SignificanceMigraineurs may have increased responsiveness to rTMS because of a cortical dysfunction that changes before a migraine attack.