Functional MRI in migraine

The underlying mechanisms of migraine are complex and heterogenous. Advances in neuroimaging techniques during the past few decades have contributed to our understanding of migraine pathophysiology. Brain function in migraine patients has been widely explored using functional MRI (fMRI). This review will highlight the major fMRI findings that characterize the different phases of migraine.The migraine attack starts with hypothalamic hyperexcitability and early reorganization of the common ascending pain and central trigeminovascular pathways. Moreover, the visual cortex becomes hyperexcitable during the aura phase. During the headache phase, further disruptions of the pontine, thalamic, sensorimotor and visual networks occur, although the hypothalamic activity and connectivity normalizes. The visual cortex remains hyperexcitable during the postdromal phase. Asymptomatic migraine patients can also experience functional alternations of pain and visual processing brain areas. At present, the heterogeneity of the asymptomatic phase and fMRI findings make it difficult to find common denominator.fMRI studies have captured functional brain changes associated with migraine phases, leading to an improvement of our understanding of migraine pathophysiology. Further MRI studies are needed to disclose whether the migraine attack is triggered by intrinsic brain dysfunction or external factors.