Somatosensory evoked high-frequency oscillations in migraine patients

To explore additional evidence concerning generators of somatosensory evoked high-frequency oscillations (HFOs). Methods We recorded HFOs in migraine patients. Subjects were 19 healthy normal subjects and 19 migraineurs. Electrical stimuli were delivered alternately to the right and left median nerves at their wrists. EEGs were recorded from C3′-Fz, C4′-Fz, Erb1–Erb2, Erb2–Erb1 and Cv6-Fz using a 0.3 Hz low-frequency filter and a 3000 Hz high-frequency filter. Responses to 5000 stimuli were averaged. For separation of HFOs from underlying N20, the digitized wide-band signals were digitally bandpass filtered (400–800 Hz) and averaged. Results There were no significant differences in peak latencies and amplitudes for N9, N13, N20 and P25 components between normal controls and migraineurs. Root-mean-square amplitudes for HFOs in migraineurs were significantly diminished compared with normal controls. Conclusions A diminished inhibitory mechanism in the somatosensory system may exist in migraineurs. It remains to determine what cell populations contribute to generating HFOs. Significance This indicates that there is a dysfunction in cortical information processing in the somatosensory cortex of migraineurs.