Visual Snow—Persistent Positive Visual Phenomenon Distinct from Migraine Aura
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Patients with visual snow complain of uncountable flickering tiny dots in the entire visual field similar to the view of a badly tuned analogue TV channel (TV snow). The symptoms are often continuous and can persist over years. This condition is grouped among the persistent visual phenomena in migraine, although it clinically presents a unique entity distinct from persistent migraine aura or migraine aura status. Here, we review the recent literature leading to the identification of the visual snow syndrome. The additional visual and non-visual symptoms are described in detail, and criteria are presented for future studies. Using these criteria, the relationship to migraine and typical migraine aura was recently evaluated. Further, patients with visual snow differ from controls in respect of hypermetabolism in the supplementary visual cortex (lingual gyrus). This provides evidence that visual snow, despite being purely subjective in the individual patient, has a clear biological basis. The area of hypermetabolism overlaps with the functional correlates of photophobia in migraine supporting the close relationship of migraine and visual snow.
KeywordsVisual snow Migraine Aura FDG PET Persistent visual phenomena Headache
Positron emission tomography
CJS was supported by the German Research Foundation [SCHA 1676/1-1] and the Friedrich Baur Foundation of the University of Munich [58/14].
Compliance with Ethics Guidelines
Conflict of Interest
Christoph J. Schankin: travel grant by Allergan and Boehringer Ingelheim and speaking honorarium by Boehringer Ingelheim and Novartis.
Peter J. Goadsby: Dr. Goadsby reports grants and personal fees from Allergan, grants and personal fees from eNeura, personal fees from Autonomic Technologies Inc, grants and personal fees from Amgen, personal fees from Bristol-Myers Squibb, personal fees from AlderBio, personal fees from Pfizer, personal fees from Zogenix, personal fees from Nevro Corp, personal fees from Impax, personal fees from Dr. Reddy, personal fees from Zosano, personal fees from CoLucid, personal fees from Eli Lilly, personal fees from Medtronic, personal fees from Avanir, personal fees from Gore, personal fees from Ethicon, personal fees from Heptares, personal fees from NuPathe, personal fees from Ajinomoto, personal fees from Teva, outside the submitted work.
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This article does not contain any studies with human or animal subjects performed by any of the authors.
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