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Neuro-Ophthalmology News

The Visual Snow Conference: May 5, 2018, University of California San Francisco

Pelak, Victoria S. MD

Section Editor(s): Digre, Kathleen B. MD

Author Information
Journal of Neuro-Ophthalmology: September 2018 - Volume 38 - Issue 3 - p e17-e18
doi: 10.1097/WNO.0000000000000693
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On May 5, 2018, the Visual Snow Initiative hosted a half-day conference at the University of California San Francisco, which was spearheaded by Peter Goadsby, MB BS, MD, PhD, a neurologist and leading expert in headache medicine from University of California San Francisco, and King's College in London. The Visual Snow Initiative recently was formed by Sierra Domb, a visual snow syndrome sufferer, and her father and businessman Paul Domb, to promote awareness and host the conference with the aim of stimulating research for further understanding and treatment. There were 143 registered participants in attendance and 8 speakers, including Sierra Domb, who began the conference with a moving description of her personal experience with the diagnosis of visual snow and her goals to promote awareness. Speakers were from multiple disciplines, including neurologists with expertise in headache, neuro-ophthalmology, and behavioral neurology; a research neuropsychologist; a vision-systems engineer; a data consultant and public speaker who suffers from visual snow; and an oculoplastic surgeon. After the talks, the speakers led a panel and took questions from audience members who identified themselves as patients and family and friends, as well as parents of children with visual snow syndrome.

The diagnosis of visual snow has evolved since its original description by Liu et al (1) in 1995. It was postulated to be a persistent positive visual phenomena in migraineurs. Speakers reflected on the fact that it is now recognized as a condition associated with migraine in 30%–60% of patients, with 27% reporting migraine visual aura (2), but visual snow is a separate entity with proposed criteria by Schankin et al (3), which include associated visual and nonvisual symptoms (see below). Speakers reviewed that cortical hyperexcitability with thalamocortical dysrhythmia are potential mechanisms for the ongoing and persistent symptoms (4,5). In addition to visual snow (i.e., the visual static symptom) persisting for more than 3 months, the International Headache Society diagnostic criteria specify that patients also must have 2 of the following 4 symptoms: excessive entoptic phenomenon, palinopsia, photophobia, and nyctalopia (Table 1) (6). Patients frequently experience other persistent sensory stimuli, such as tinnitus and somatosensory symptoms, and some have signs of tremor and balance issues (5). Reports vary in regards to sex predominance of the syndrome, with some indicating male and others indicating female predominance.

TABLE 1.
TABLE 1.:
Diagnosis of visual snow from The International Classification of Headache Disorders, 3rd edition (6) and Schankin et al (3)

After Sierra Domb's introduction, Jim Fulton, a vision-systems engineer, spoke about the potential roles of the pulvinar, perigeniculate nucleus, and the thalamic reticular nucleus in the generation of visual snow. He also reviewed results from an online survey of people with visual snow, including only 2 of 150 survey participants reporting color in the visual snow static experience. However, this was distinct from the research update given at the conference by Dr. Peter Goadsby, who indicated that data from an ongoing online survey of 1,000 people with visual snow reveal that, on average, sufferers experience at least 2 of 4 types of visual snow static: 1) black and white, 2) colored, 3) flashing, and 4) transparent, and nearly half experienced colored static. Dr. Goadsby briefly reviewed published data from his group regarding a [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography imaging study that showed hypermetabolic activity while at rest within the left lingual gyrus and the right cerebellum. Victoria Pelak, MD, neuro-ophthalmologist and behavioral neurologist from the University of Colorado School of Medicine, gave audience members an overview of how visual snow and associated symptoms map onto the afferent visual pathway and reviewed neuronal hyperexcitability in the visual pathways as a potential mechanism for symptom development. From Monash University Department of Neurosciences in Australia, neuro-ophthalmologist Owen White, MD, PhD, and cognitive neuroscientist Joanne Fielding, PhD, reviewed how underlying brain pathways that serve visual attention and ocular motility show measurable behavioral changes in people with visual snow syndrome. Their past collaborative work on center-surround contrast suppression and luminance increment threshold abnormalities in visual snow was supported by additional findings presented by Dr. Fielding, which included ocular saccade-attentional paradigms. These data provided evidence that outcome measures could be used to assess treatment efficacy in future clinical trials, which is critical given that visual snow symptoms are measured by subjective report at this time. Dr. Yasser Khan, an ophthalmologist and oculoplastic surgeon at McMaster University in Canada, provided a physician's prospective on becoming involved in caring for patients with visual snow, which began after he listened carefully to a patient suffering from excessive entoptic phenomenon. Matthew Renze, a data science consultant, spoke about his personal experience with visual snow and how he learned to overcome the intense and disabling sensory overload through a structured practice of meditation, mindfulness, and a healthy diet, which was not previously a part of his busy life.

Questions from the audience were taken by the panel, and many audience members asked about potential connections of visual snow to other disorders such as Lyme disease, infections, or antibiotic use, and panel members commented that they were aware of these types of patient-reported associations, but there is no evidence that verifies such connections. Curiously, one audience member asked about an association between his diagnosis of erythromelalgia and visual snow. Panel members were unaware of such, but Sierra Domb noted that she had been recently diagnosed with the same rare condition. Erythromelalgia is a rare autosomal dominant neuropathy caused by a mutation of the voltage-gated sodium channel α-subunit gene SCN9A, and mutations in this subunit are believed to result in neuronal hyperexcitability (7). Some audience members noted the difficulty they had in finding a doctor who recognized their symptoms as visual snow, and one person noted that she suspects she has visual snow but was in search of a doctor to verify her diagnosis. Parents accompanying their young children with visual snow conveyed their experiences and the impact the syndrome has had on their lives, which were particularly poignant. As noted in the literature, there were children at the conference who noted that their vision was always “filled with static” and also suffer from associated visual symptoms, as noted in the diagnostic criteria.

Overall, feedback from participants was very positive, and many agreed that future research collaborations will develop from the conference. Although no current plans are underway for a second conference, continued efforts to increase awareness are being undertaken by the Visual Snow Initiative, which also has a goal of posting video content of this conference on their website.

REFERENCES

1. Liu GT, Schatz NJ, Galetta SL, Volpe NJ, Skobieranda F, Kosmorsky GS. Persistent positive visual phenomena in migraine. Neurology. 1995;45:664–668.
2. Bou Ghannam A, Pelak VS. Visual snow: a potential cortical hyperexcitability syndrome. Curr Treat Options Neurol. 2017;19:9.
3. Schankin CJ, Maniyar FH, Digre KB, Goadsby PJ. “Visual snow”—a disorder distinct from persistent migraine aura. Brain. 2014;137:1419–1428.
4. Schankin CJ, Maniyar FH, Sprenger T, Chou DE, Eller M, Goadsby PJ. The relation between migraine, typical migraine aura and “visual snow.” Headache. 2014;54:957–966.
5. Lauschke JL, Plant GT, Fraser CL. Visual snow: a thalamocortical dysrhythmia of the visual pathway? J Clin Neurosci. 2016;28:123–127.
6. Headache Classification Committee of the International Headache Society. The International Classification of Headache Disorders. London, United Kingdom: Sage Publications Ltd, 2018. Available at: http://journals.sagepub.com/doi/pdf/10.1177/0333102417738202. Accessed June 26, 2018.
7. Tang Z, Chen Z, Tang B, Jiang H. Primary erythromelalgia: a review. Orphanet J Rare Dis. 2015;10:127.
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