Visual evoked potentials and color doppler sonography of ocular arteries in migraineurs with visual aura

ABSTRACT

Disorders of the visual function in migraineurs have been recognized by neurophysiological methods for many years. However, studies of the cortical visual evoked potentials have yielded contradictory results. Changes in the retrobulbar hemodynamic in migraineurs with visual auras, have not been researched extensively. The aim of the present work is to study the visual evoked potentials as well as the blood flow velocity, pulsatility index [PI] and resistance index [RI] in the ophthalmic and central retinal arteries in migraine patients with and without aura. The present study included thirty five migraine patients and fifteen healthy control subjects. Twenty patients have exclusively migraine with visual aura [MA], and fifteen without aura [MO]. The study was carried out during the headache-free periods, and all the patients and control groups were subjected to complete general examination, thorough neurological and full ophthalmic examination, pattern-shift visual evoked potential [PS-VEP] assessment, and color doppler sonography of the ophthalmic [OA] and central retinal [CRA] arteries. PS-VEP assessment showed prolongation of the N75, P100, and N 145 latencies of the MA group, than in the MO and control groups, but significant difference was found only between the N75 and N145 latencies of the MA and control groups [P= 0.032, 0.039 respectively]. The mean P100-N145 amplitude of the MO group was significantly higher than that of the control group [P=0.021]. The mean P100-N145 amplitude of the MA group was lower than that of the MO group but still higher than the control group although none of the differences reached significant level. The mean PI of OA and CRA, mean RI of CRA, and mean end diastolic velocity of the CRA were significantly higher in MA group than in the control subjects. Migraineurs without aura [MO], when compared to the controls, they showed the same trend as the MA group, but none of the differences was statistically significant. The present study gives support to the role of cerebrovascular factors and ischemic damage in the prolongation of the VEP wave latencies and decreased P100 amplitude in migraine patients with visual aura. It also showed evidence of dysfunction in the retrobulbar circulation and hemodynamic changes that may explain some of the visual symptoms reported by most migraineurs