Editorial: Visual Snow: Old Problem, New Understanding

Abstract

Visual snow syndrome (VSS) is a well known disturbance of visual perception. It has been misdiagnosed over the years as either being an untreatable form of migraine or, conversely, a manifestation of psychological disturbance. It was eventually recognized as a separate entity in 1995 (1) and was subsequently codified as a syndrome in a series of papers from 2012 to 2014 (2-5), and expanded on as part of a more widespread disturbance of sensory processing on the basis of its association with numerous other sensory disturbances (6, 7). It is described as a very rare entity (8) and yet recent studies have suggested that it may affect as much as 2.2% of the community (9).VSS is a clinical diagnosis with the main criterion of persistent pan-field "TV-snow" or "pixilation, " extending beyond 3 months, in conjunction with two of either photophobia, enhanced entoptic phenomena (e.g., blue field phenomena, floaters), palinopsia, or nyctalopia (4, 5). Numerous other non-visual or even non-perceptual symptoms have been identified, including migraine, tinnitus, vestibular disturbance (consistent with persistent perceptual postural disorder), fibromyalgia, migratory paresthesia, and endogenous perceptual phenomena such as depersonalization and derealization (6,7,10).Recent work has demonstrated both structural (11-15) and physiological/functional signatures of the disorder (16-18) (Foletta et al.; Solly et al.), confirming this as a separate disorder from migraine and, in conjunction with the above quoted studies, introduces the concept of impaired central processing as a new group of disorders deserving of study, as well as providing a means for study.Thus, the recent interest in visual snow has enfranchised a group of patients previously mislabeled as neurotic or having untreatable migraine. It has also provided a means for evaluating potential treatment strategies, permitting trials going forward.This Research Topic of Frontiers in Neurology, Section Neuro-Ophthalmology is focused on the current advances in the field of visual snow research. It demonstrates the progress made in clinical, paraclinical, and experimental aspects with the ultimate aim to reduce symptoms and improve quality of life in these patients.Currently, it is still difficult to determine what drives patients to develop VSS later in life or early during childhood. In early studies, eye examinations were in general normal (1, 5) but it has remained unclear how much ophthalmic examination is necessary. The retrospective study from this Research Topic reviewed detailed ophthalmology exams in 52 patients and revealed that patients presenting with typical VSS may not need more than the standard neuro-ophthalmologic examination and automated perimetry (Vaphiades et al.). From the beginning, it has been suggested that VSS might be a migrainous phenomenon, essentially driven by the comorbidity and the Publisher's Note: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or ...

Simultaneous 18F-FDG PET/MR metabolic and structural changes in visual snow syndrome and diagnostic use

“…In the past few years, VSS has been characterized in more detail by clinical, neuroimaging and neurophysiologic investigations [10][11][12][13][14][15][16]. VSS seems to involve aberrant processing of visual information in the supplementary visual cortex, and there is increasing evidence that VSS involves multiple mechanisms with cortical dysfunction also outside the visual system.…”