The photic driving response in electroencephalogram in migraine patients

It is well known that the migraine patients indicate abnormal information processing such as photic supersensitivity. And it is high incidence and an aggravation factor of migraine attack. In addition, it is included in the diagnostic criteria of ICHD-II. However, the underlining mechanism is still open for discussion. Our study aimed to investigate the photic driving responses of the electroencephalogram (EEG) with source localizing method. We recorded spontaneous eyes-closed resting EEG from 20 electrodes on the scalp during their inter-ictal phase. Stroboscope flashes consisting of 3-5-8-10-13-15-18-20 Hz were used. After recording, each photic stimulation was selected respectively. And we examined the relation between clinical backgrounds and the prophylaxis. In addition, we analyzed EEG by FFT and observed the frequency peaks and its topographies responded for photic stimulation. The photic driving response could be observed in higher flashing rate than 15 Hz in addition to lower flashing rate. And the case as having photic supersensitivity tended to show a lot of photic driving regardless of migraine subtypes. Moreover, in topographies, their activated areas were shifted anterior from fundamental driving to harmonic driving for each photic frequency. This anterior shift was more evident for longer duration of illness, although no significant differences between subgroups. And the global field power (GFP) value had a positive correlation between the duration of the illness. We conclude that high incidences of photic hypersensitivity and photic driving response in migraineurs were confirmed. The underlying mechanism of photic hypersensitivity might result in sensitization of limbic system.