Significance and Limitations of Visual Evoked Potentials in the Study of Pathophysiology of Migraine
Abstract
Dysfunction of the central nervous system is considered to be the primary factor in the pathophysiology of migraines. Neurophysiological techniques enable non-invasive testing of pathophysiological hypotheses of migraines.
In this respect, Visual evoked potentials (VEP) are historically and currently the leading modality, even though the traditional assessment of VEP did not prove useful. Abnormal processing of visual information in migraines is demonstrated by reduced or absent physiological, decline in VEP amplitude (habituation deficit) during prolonged visual stimulation.
This review article presents a selection of studies with VEP for migraine, including recent studies using neural excitability modulation (transcranial magnetic stimulation, hyperventilation and light deprivation). The findings from studies of habituation to VEP in migraines can support the theory of reduced preactivation thresholds of the cortex in the interictal period, based on the predominance of inhibitory mechanisms due to thalamo-cortical functional dissociation.
However, migraine is characterized by cyclic changes in cortical activity - there is no VEP habituation deficit in preictal and ictal phases.