Heterogenous migraine aura symptoms correlate with visual cortex functional magnetic resonance imaging responses

    loading  Checking for direct PDF access through Ovid

Excerpt

The classical presentation of migraine aura is the scintillating scotoma‐a gradually developing visual field defect bordered by a glittering serrated arc.1 However, the clinical features of migraine aura are highly variable between patients2 and between attacks within the same patient.3 Although visual symptoms are the most common aura manifestation, occurring in 99% of aura episodes,4 these are often not archetypical scotomas, but rather, for example, wavy lines, small bright dots, or white flashes of light.2 A probable underlying cause of aura is the electrophysiological phenomenon of cortical spreading depression (CSD), which is characterized by a spreading wave of intense gray matter depolarization followed by suppression of neuronal activity.6 Direct evidence of CSD during aura in patients is still lacking, but previous studies have shown changes in regional cerebral blood flow corresponding to those seen in animals during CSD using planar xenon,7 single photon emission computed tomography (SPECT),8 and positron emission tomography (PET).9 Detection of CSD waves by blood oxygenation level–dependent (BOLD) functional magnetic resonance imaging (fMRI) has been validated in vivo in the feline brain.10 One study using BOLD fMRI reported signal changes with several characteristics of CSD during a typical scintillating scotoma in a migraine patient provoked by physical activity.12 Similar fMRI studies during migraine aura has not been performed, probably because migraine aura is notoriously difficult to study due to the unpredictable and short‐lasting nature of attacks, and because no efficient and consistent method for experimental aura provocation has been developed.13 In the present study, we used state of the art high‐field BOLD fMRI during visual stimulation combined with retinotopic mapping to investigate migraine patients during various forms of aura symptoms induced by hypoxia, sham hypoxia, or physical exercise with concurrent photostimulation. We hypothesized that BOLD signal changes characteristic of CSD would occur during aura and that specific visual symptoms would correspond to different BOLD signal changes.

Related Topics

    loading  Loading Related Articles