Reduced electroencephalogram power and no change in peak alpha frequency in individuals with chronic migraine: a cross-sectional investigation

OBJECTIVES: Electroencephalographic (EEG) studies suggest chronic migraine (CM) is associated with increased global power, especially in somatosensory cortex. Furthermore, recent studies suggest chronic pain is associated with a reduced peak alpha frequency (PAF) and increased infra-slow oscillatory (ISO) power. Our aim was to determine the spectral power, PAF and ISO in CM. METHODS: A 64-electrode EEG was used to record resting state activity in 28 CM and 28 controls. We calculated ISO, delta, theta, low and high alpha, low and high beta power globally and at each EEG electrode and determined PAF. RESULTS: CM was associated with reduced log-transformed absolute power, delta low power and high alpha and low beta power distributed across the scalp compared to controls. Within relative power, CM showed increased low alpha and reduced high beta compared to controls. In an exploratory analysis, we found that the presence of a headache or migraine did not alter these absolute power and relative power reductions. We found no significant ISO power or PAF differences between groups, either globally or within spatial cortical subregions. CONCLUSIONS: CM is associated with altered EEG absolute and relative power characteristics in specific frequency bands, but no change in PAF. Our results suggest that the underlying mechanisms are different between chronic migraine and other forms of chronic pain.