Functional MRI-BOLD of visually triggered headache in patients with migraine

Background: Spreading depression of Leao has been hypothesized as the basis for the visual aura of the migraine attack, supported by cerebral blood fl ow measurements of spreading hypoperfusion. The early depolarizing or activ ation phase of experimental spreading depression, however, is associated wi th a transient but pronounced cerebral blood flow increase that precedes sp reading hypoperfusion. Objective: To study this early phase of the migraine attack, we investigate d visually triggered attacks of headache and visual symptoms using a red-gr een checkerboard stimulus in patients with migraine. Interventions: We studied occipital cortex activation during visual stimula tion by measuring occipital cortex perfusion with functional magnetic reson ance imaging-blood oxygenation level-dependent contrast in 10 patients with migraine with aura and 2 patients with migraine without aura and 6 healthy subjects. Results: In 6 patients with migraine with aura and 2 patients with migraine without aura, their typical headache with (n = 2) or without visual change was visually triggered at 7.3 minutes (mean time) after visual stimulation began. In 5 of these patients, the onset of headache or visual change, or both, was preceded by suppression of initial activation (mean onset time, 4 .3 minutes; P<.001) The suppression slowly propagated into contiguous occip ital cortex at a rate ranging from 3 to 6 mm/ min. This neuronal suppressio n was accompanied by baseline contrast intensity increases that indicated v asodilatation and tissue hyperoxygenation. Conclusions: We conclude that visually triggered headache and visual change in patients with migraine is accompanied by spreading suppression of initi al neuronal activation and increased occipital cortex oxygenation. We postu late that this spreading suppression may be associated with initial activat ion of a migraine attack, independent of whether there are associated aura symptoms. We further postulate that there may be an association between vas odilation accompanying the initial stage of suppression and the induction o f headache.