ABSTRACT
Since the initial description of cortical spreading depression (CSD) by Leao, there has been growing evidence that CSD is the underlying pathomechanism of the migraine aura (Table 1). CSD is a slowly propagating wave of neuronal and glial depolarization that spreads across the cortex with a speed of 3 to 5mm/min. It is accompanied by a short-lasting dramatic increase in regional cerebral blood flow (rCBF) followed by a long-lasting rCBF hypoperfusion. Recent functional magnetic resonance imaging (fMRI) (1) and magnetoencephalography (MEG) (2) studies in men strongly support the occurrence of CSD during visual migraine aura. Assessment of the speed of progression of the visual field defect during migraine aura, using Humphrey field chart, confirms the rate of progression of 3.6mm/min (3). The fact that, among all aura symptoms, the visual aura is the most common (4) may reflect the hyperexcitability of the occipital cortex of migraineurs.
