Physiological parameters as biomarkers of migraine.

We review physical signs and measurements from neurophysiological research, which may be considered biomarkers of migraine. Most studies show that information processing is abnormal in migraineurs. Studies of trigeminal nociception are in line with a central sensitization during the attack. The best documented abnormality is an interictal lack of habituation in migraineurs, with a normalization during the headache state, which has been shown using evoked and event-related potentials. Together with a diminished energy reserve found in MR-spectroscopy studies, these results suggest a possible role of increased energy consumption in attack generation. Importantly, to date, no neurophysiological marker has a high enough sensitivity and specificity to point out the single migraine patient. Therefore, these biomarkers are to be understood as tools for research and are not to be used for diagnostic purposes.