Vector analysis of visual evoked potentials in migraineurs with visual aura.
OBJECTIVE
To assess the capability of vector analysis of visual evoked potentials (VEPs) for revealing alterations in posterior visual pathways in migraineurs with visual aura.


METHODS
VEPs to pattern reversal (PR) and LED goggle stimulation were obtained in 23 patients suffering from migraine with visual aura, in an orthogonal Fpz-Oz and T3-T4 montage and displayed as a two-channel Lissajous' trajectory. VEP latency and amplitude at Fpz-Oz, bc segment amplitude (V) and bc vector orientation angle (theta) were compared with a previously collected normative database for individual assessment, and group comparisons with the previously collected normal sample were made. Electrophysiological measures were also correlated with time from onset of disease and from the last crisis, and with the side of symptoms.


RESULTS
No individual alterations in VEP latency or amplitude were observed. However, 36.4% of patients showed alterations in vector orientation to PR and 78% to LED goggles. Group differences with respect to normal subjects were found not only in vector orientation but also in midline VEP and V, only for PR stimulation. A significant relationship was found between the laterality of vector deviation and the laterality of symptoms.


CONCLUSIONS
Vector analysis of VEP revealed alterations possibly corresponding to asymmetrical visual cortex activation in migraineurs with visual aura, mainly to diffuse light stimulation.


CONCLUSIONS
An electrophysiological parameter of individual value for revealing asymmetric activation of visual cortex in migraineurs is proposed.
Hospital Universitario de Los Andes, Unidad de Neurología, 5101 Mérida, Venezuela. coutinpe@hotmail.com
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Coutin-Churchman
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Padrón de Freytez
D000293:Adolescent; D000328:Adult; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020325:Migraine with Aura / Q000503:physiopathology*; D010775:Photic Stimulation; D011930:Reaction Time; D015348:Vision, Binocular