The pain in migraine beyond the pain of migraine.

Migraine is a complex and often disabling brain disorder that affects about 15 % of the population. The diagnosis of migraine is based on clinical features as proposed by the International Headache Society criteria but they are somewhat subjective and arbitrary. Functional neuroimaging of patients with migraine has been recently employed to study the underlying pathophysiology of headache. These studies have suggested that migraine involves functional and structural plasticity of both central and peripheral nervous system. Insights into the fundamental physiology of migraine have been limited by the lack of methods available to detect the pathophysiological background of critical moment of migraine attack onset that is greatly different from the onset of pain or pain phase of a migraine attack. In order to overcome methodological caveats in detecting "migraine origin" or a "migraine generator", functional brain imaging has been lately dominated by experimental acute-pain research. Along this research line functional imaging using experimental pain stimulation have greatly improved our knowledge about physiological or dysfunctional neuronal activity pattern in patients with migraine, but at the same time, it is important to emphasize that experimental pain is different from spontaneous migraine pain.