Unveiling the visual system in migraine: Electrophysiological evidence from electroretinogram and visual evoked potential

Background Since there is evidence that the bioelectrical activity in migraineurs' visual cortex varies significantly throughout the migraine cycle and that the retina, according to embryology, is an extension of the cortex, and has similar angiogenesis configurations and regulatory mechanisms, so the aim of this study was to investigate the cortical activity, functional and electrophysiological retinal changes in migraine patients using different modalities of electroretinogram (flash full field, multifocal and pattern) during interictal period. Methods Fifty-six migraine patients according to the international headache society, third edition and fifty-six healthy subjects age and sex matched as control group all were subjected to assessment of cortical activity, functional and electrophysiological retinal changes using visual evoked potential and electroretinogram (flash full field, multifocal and pattern). Results In terms of flash full field ERG findings, there was a statistically significant delayed latencies of both photopic and scotopic a and b wave and lower amplitudes of scotopic a and b waves among patients compared to controls (P < 0.001). Multifocal ERG showed that there were significantly lower amplitudes of N1 wave of zones 1 and 5 (P < 0.001) and P1 wave amplitudes in zones 2, 4 and 5 among patients compared to control (P = 0.039, < 0.001, < 0.001) respectively. As regards pattern ERG and visual evoked potential P50 and P100 latencies and amplitudes showed no statistically significant difference between patients compared to controls. Conclusion These findings suggest that migraine patients had functional retinal changes, even during headache-free periods that could be related to selective neuronal and/ or vascular alterations.