Long term decline of P100 amplitude in migraine with aura

Objectives-To investigate visual function in migraine using visual evoked p otentials. Methods-Electroretinograms (ERGs) and visual evoked potentials (VEPs) to si ngle flash (SF) and pattern reversal (PR) stimuli were studied in 92 migrai ne subjects and 62 controls. Results-In subjects with migraine, ERGs to single hash were normal. Mean la tencies of the P1 and P2 waves in the SFVEP were increased at the occiput b y 6% and 4% respectively, but normal at the vertex. Mean latency of the P10 0 wave in the PRVEP was increased by 5%. These increases were not related t o the presence or absence of an aura or to the duration of migraine. P100 a mplitude showed a more complex abnormality, It was increased in migraine wi thout aura by 23% compared with controls, regardless of duration of migrain e. In migraine with aura it was similarly increased, by 23%, in cases of sh ort duration, but in addition it showed a sharp decline with duration. In c ases with a duration of 30 or more years it was 36% less than in cases of s hort duration, and 21% less than in controls, Conclusions-Subjects with migraine have constitutionally prolonged VEP late ncies and increased P100 amplitude, but the latter declines to below normal in cases with a long history of migraine with aura. This decline may refle ct subtle neuronal damage within the visual system from repeated transient ischaemia experienced during the aura. Future electrophysiological and othe r studies will need to be controlled for duration of migraine history.