Background: Brief 5Hz repetitive transcranial magneticstimulation (rTMS) trains at 120% of the resting- motorthreshold(RMT) intensity determine in healthy subjects apotentiation of motor evoked potentials (MEPs), likely dueto short-term presynaptic plasticity facilitation. We recentlyshowed paradoxical intensity-dependent MEP changes to5Hz rTMS in migraine with MEP facilitation at 110% andinhibition at 130% RMT. This provides evidence of bothhyper-responsivity and self-limiting hyperexcitabilitycapacity in migraine, likely due to earlier activation ofinhibitory homeostatic plasticity mechanisms. To explorethis, we applied in migraineurs cathodal transcranial DirectCurrent Stimulation (tDCS) to reduce motor-corticalexcitability and subsequently reassess motor-corticalresponse to 5Hz rTMS trains at 130% RMT- intensity.Methods: 10 migraine with aura patients received 5HzrTMS of motor cortex at 130% RMT intensity (10 pulses),recording MEP from contralateral abductor pollicis brevis(APB). This protocol was preconditioned by cathodal tDCS(10 min, 1mA intensity). Sham cathodal tDCS was used ascontrol.Results: As expected MEP amplitude decreased significantlyduring trains of 5Hz before tDCS preconditioning orwith sham tDCS. Conversely, after inhibitory preconditioningwith cathodal tDCS, 5Hz rTMS trains determined areduction in the first MEP size and a trend toward MEPfacilation during the trains.Conclusions: Inhibitory cathodal tDCS preconditioning isable to normalize the response of migraine motor-cortex torTMS trains at 130% of RMT. This supports the hypothesisthat in migraine motor cortex the mechanisms of short-termpresynaptic plasticity evaluated by 5Hz rTMS trains couldbe affected intericatally by an abnormal increased corticalexcitability level.
|Numero di pagine||1|
|Stato di pubblicazione||Published - 2011|