S148 Evoked potential studies in migraine: Overview of results and hints to neuromodulation therapy

Abstract

Objectives To present an overview of previous studies on evoked potentials in migraine with a hint to neuromodulation therapy. Methods Review of results of such studies published in peer reviewed journals. Results and discussion Analysing amplitude changes during repetitive stimulation in consecutive blocks of visual evoked potentials (VEP) a lack of habituation has been demonstrated in migraine patients with or without aura in the interictal period. This contrasted with normal habituation, e.g. amplitude decrease during repetitive stimulation in healthy subjects. A comparable method using auditory stimuli is repetition of stimulation with increasing intensity. In migraine patients amplitudes increased markedly with increasing stimulation intensity whereas little amplitude change was found in healthy controls. Initial amplitudes of both sensory modalities showed a negative correlation with amplitude changes during stimulation. Both habituation of visual and intensity dependence of auditory evoked potentials normalised the day before and during migraine attacks.Studies using single pulse of transrancial magnetic stimulation (TMS) performed during the interictal period yielded contradictory results due to methodological differences, including timing of testing. Repetitive TMS (rTMS) is able to change cortical excitability depending on the rate of stimulation. High-frequency repetitive rTMS was able to normalize the habituation deficit of VEP. Conclusion and significance lack of habituation and low interictal was demonstrated in migraine patients in the interictal period using different sensory modalities. rTMS was able to normalize deficient habituation. This might give a pathophysiological background to decide on modalities used in neuromodulation therapy in migraine.