Clinical and pathophysiological contribution of event-related potentials used to study migraine headache.

Event-related potentials are electric brain manifestations evoked by menial activities. This neurophysiological technique is able to describe temporal succession of cognitive processing and allows to measure the neurobiologic al correlates of each cognitive activity The evoked potentials of the oddba ll paradigm and the Contingent Negative Variation (CNV) are also concerned by clinical applications in neuropsychiatry, in neurology and in psychophar macology. In the case of migraine, the studies with CNV recorded between mi graine attacks are characterized by two major phenomena, cerebral hyperreac tivity and lack of habituation to repetitive stimuli. From cognitive point of view, this can be interpreted as a difficulty from migraine sufferers to adapt their information-processing to environmental constraints. From neur ological point of view, this trouble is related with dysregulation of norep inephrin and serotonin ascending pathways. Studies with the oddball paradig m potentials remain non consistent. The mismatch between different methodol ogies could explain such a lack of consistency. The neurophysiological stud ies have contributed to new physiopathological hypothesis of migraine. Thos e hypothesis reveal that a shift in the brain metabolic homeostasis could b e the common factor of migraine attacks. The clinical contribution of event -related potentials is of little use in the diagnosis of migraine. But two purposes have been suggested: the differential diagnosis between common mig raine and tension-type headaches and the monitoring of beta-blocking agents prophylaxis.