Scintillating scotoma is the most common visual aura preceding migraine and was first described by 19th century physician Hubert Airy (1838–1903). It may occur as an isolated symptom without headache in acephalgic migraine. While many variations occur, the scintillating scotoma usually begins as a spot of flickering light in the center of the visual fields, which obscures vision to some degree. It then expands into shimmering arc(s) of white or colored lights. The arc of light gradually enlarges, becomes more obvious, and may take the form of a definite zig-zag pattern, sometimes called a fortification spectrum, because of its resemblance to the battlements of a castle or fort. It may be bilateral or unilateral. It may be difficult to read or drive while the scotoma is present, although normal central vision may return several minutes before the scotoma disappears at the periphery. Symptoms typically resolve within 15-30 minutes, leading to the headache in classic migraine, or resolving without consequence in acephalgic migraine.

• Scotoma
• Cortical spreading depression

• AgingEye Times
• Imigraine.Net – includes images of scintillating scotomata

• “Possible Roles of Vertebrate Neuroglia in Potassium Dynamics, Spreading depression, and migraine”, Gardner-Medwin, J. Exp. Biology (1981), 95, pages 111-127.
• “Mechanisms of migraine aura revealed by functional MRI in human visual cortex”, Hadjikhani et al., PNAS 98 (2001), pages 4687-4692.

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