Abnormality of visual neuromagnetic activation in female migraineurs without aura between attacks.

OBJECTIVE: The present study aimed to preliminary explore the abnormal neuromagnetic activation in female migraine patients between attacks using magnetoencephalography (MEG) and pattern reversed visual evoked magnetic fields (PR-VEFs). METHODS: A total of 17 female migraine subjects during the headache-free phase and 17 healthy controls (HC) were studied using a 275-channel magnetoencephalography (MEG) system. In this study, visual evoked magnetic fields (VEFs) were generated by a pattern-reversal check as the visual stimulus. The average of 100 VEFs was evolved by different half patterns were averaged and used to analyze waveform, spectrum, and source location within two frequency ranges (5-100 and 100-1000 Hz), respectively. RESULTS: In migraine subjects, the latency of second peak of VEFs (VIIs) showed significant prolongations when compared with HC. On the sensor level, the cortical spectral power in migraine subjects was similar to that of HC in the 5-100 Hz range and was lower in the 1000-1000 Hz range. There was a decrement of source strength in the visual cortex in migraine patients when compared to HC in both the 5-100 and 100-1000 Hz frequency range. Moreover, there was a similar odds of activation in 5-100 and 100-1000 Hz frequency ranges in the area beyond the primary visual cortex between the two groups. In addition, no correlation was observed between clinical data (intensity of headache, headache-history duration, the frequency of headaches) and MEG results. CONCLUSIONS: The findings presented in the current study, suggested that interictal cortical activation following a visual stimulus was low in female migraine patients. The low pre-activation was detected in the visual cortex using VEF and MEG in both low and high-frequency band. Our results add to the existing evidence that cortical interictal excitability change may be relative to the pain-module mechanism in migraine brains. Thus, our data improved the apprehension of the cortical disorder of migraine in the high-frequency domain.

Abnormal cortical activation in females with acute migraine: a magnetoencephalography study.

OBJECTIVE: The objective of this study was to investigate functional abnormalities of the brain in females with migraine using magnetoencephalography (MEG) and a finger-tapping task. METHODS: Twenty-nine female patients with migraine (aged 16-40years) and age- and gender-matched healthy controls were studied with an MEG system at a sampling rate of 6000Hz. MEG recordings were performed during an attack in migraineurs with and without aura. Neuromagnetic brain activation was elicited by a finger-tapping task. The latency and amplitude of neuromagnetic responses were analyzed with averaged waveforms in the frequency range of 5-100Hz. The Morlet wavelet and beamformers were used to analyze the spectral and spatial signatures of MEG data from subjects in two frequency ranges of 5-100 and 100-1000Hz. RESULTS: The latency of motor-evoked magnetic fields evoked by finger movement was significantly prolonged in migraineurs as compared with controls. Neuromagnetic spectral power in the motor cortex in migraineurs was significantly elevated. There were significantly higher odds of activation in 5-30, 100-300 and 500-700Hz frequency ranges in the ipsilateral primary motor cortices and the supplementary motor area in migraineurs as compared with controls. CONCLUSIONS: Neuromagnetic signal abnormalities in this study suggest cortical hyperexcitability in females with migraine during migraine attack, which could be measured and analyzed with MEG signal in a frequency range of 5-1000Hz. SIGNIFICANCE: These findings may help to identify neurophysiological biomarkers for studying mechanisms of migraine, and may facilitate to develop new therapeutic strategies for migraine by alterations in cortical excitability.