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Fortification Spectra

Fortification spectra, also known as teichopsia, are visual hallucinations which occur as an aura, either in isolation (migraine without headache) or prior to an attack of migraine (migraine with a href="/Dictionary_of_Neurological_Signs/A/Aura.html">Aura; "classical migraine"). The appearance is a radial array likened to the design of medieval castles, not simply of battlements. Hence these are more complex visual phenomena than simple flashes of light (photopsia) or scintillations. They are thought to result from spreading depression, of possible ischemic origin, in the occipital cortex.