Visual snow

Francesca Puledda MD (

Dr. Puledda of King’s College London has no relevant financial relationships to disclose.

)
Peter J Goadsby MD PhD (

Dr. Goadsby of King’s College London and the University of California, San Francisco, received fees from Alder Biopharmaceuticals, Allergan, Autonomic Technologies Inc, Biohaven Pharmaceuticals Inc, Clexio, Electrocore LLC, eNeura, Impel Neuropharma, MundiPharma, Novartis, Teva Pharmaceuticals, Trigemina Inc, and WL Gore; consulting grants and fees from Amgen and Eli-Lilly and Company; and a grant from Celgene.

)
Stephen D Silberstein MD, editor. (

Dr. Silberstein, Director of the Jefferson Headache Center at Thomas Jefferson University, received honorariums from Abbie, Curelator, Ipsen Therapeutics, Lundbeck Biopharmaceuticals, Supernus Pharmaceuticals,  and Theranica for consulting. He is also the  principal investigator for clinical trials conducted by Amgen, ElectroCore Medical, and Teva.

)
Originally released December 27, 2019; expires December 27, 2022

This article includes discussion of visual snow, visual snow syndrome, prolonged visual disturbance, visual static, primary persistent visual disturbance, palinopsia, photophobia, nyctalopia, entoptic phenomena, migraine, prolonged visual aura, and tinnitus. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Visual snow is a neurologic condition that was first systematically and clinically defined in 2014. The main clinical feature is that of an unremitting, positive visual phenomenon present in the entire visual field and characterized by uncountable tiny flickering dots. In addition to this “static” phenomenon, patients with visual snow can experience visual symptoms of either direct neurologic origin, such as palinopsia, photophobia, and impaired night vision, or that arise from the optic apparatus, such as the entoptic phenomena. Different combinations of these additional symptoms, together with the static itself, constitute the visual snow syndrome. In the past few years, recognition of visual snow syndrome has grown considerably in both clinical neurology and neuroscience. Nonetheless, the pathophysiology, causes, and treatment of visual snow remain largely unknown.

Key points

 

• Visual snow is a newly defined neurologic disorder characterized chiefly by visual static, resembling a detuned television.

 

• The visual snow syndrome is characterized by visual symptoms of the type of palinopsia, entoptic phenomena, nyctalopia, and photophobia, in addition to the static.

 

• Little is known with regards to the pathophysiology of visual snow, as well as optimal treatment strategies for affected patients.

 

• The most frequent comorbidities of visual snow are migraine and tinnitus.

 

• Visual snow should be clinically differentiated from prolonged migraine aura and hallucinogen persisting perception disorder.

Historical note and terminology

Early clinical reports of visual snow have mostly been described in the context of larger case series of migraine patients and were defined with terms such as: “persistent positive visual phenomena” (Liu et al 1995), “persistent positive visual disturbances” (Jager et al 2005), or “persistent visual aura without infarction” (Wang et al 2008; Chen et al 2011).

The first clear description of visual snow as a unique clinical phenomenon can be found in a case report of a young female patient published in the medical literature in 2013 (Simpson et al 2013). In this paper, visual snow was also termed “positive persistent visual symptoms”.

A study published the following year provided the first systematic characterization of visual snow, distinguishing it clearly from migraine with and without aura (Schankin et al 2014a). This paper also outlined criteria for visual snow syndrome that are currently in use (Clinical manifestations section).

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