Visual aura is a common presenting symptom of migraine to both neurologists and ophthalmologists. Features such as photopsia, fortification spectra, and the slow propagation of a scintillating scotoma across the visual field are usually considered diagnostic features of the visual aura of migraine. In the vast majority of cases, the diagnosis can be made without the need for further investigations. We present 9 patients and a further 31 cases from the literature who experienced visual aura fulfilling the diagnostic criteria for migraines but caused by focal occipital pathology. Key clinical features that could help to differentiate between the visual aura of migraine and those suggestive of a structural lesion are outlined. We review current scientific theories into the pathophysiology of visual aura, drawing on clinical and basic science research, including human functional imaging studies of migraine aura and advances in the genetic characterization of familial channelopathies, in order to explain the overlap which occurs in the clinical features of visual aura associated with migraine, cortical lesions, and epilepsy. We conclude that any disease process that is able to create a state of neuronal hyperexcitability can therefore increase an individual's susceptibility to the development of cortical spreading depression, the electrophysiological correlate of the visual aura.
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