Research

https://www.mdpi.com/2075-4418/13/2/252

https://pubmed.ncbi.nlm.nih.gov/34895130/

https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-021-01355-y

Age- and frequency-dependent changes in dynamic contrast perception in visual snow syndrome

https://www.frontiersin.org/articles/10.3389/fneur.2021.723677/full

https://bjo.bmj.com/content/early/2021/10/20/bjophthalmol-2020-318653

Evaluation of treatment response and symptom progression in 400 patients with visual snow syndrome

https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8521005/

Visual Snow Syndrome as a Network Disorder: A Systematic Review

Localised increase in regional cerebral perfusion in patients with visual snow syndrome
July 14, 2021
https://jnnp.bmj.com/content/early/2021/07/13/jnnp-2020-325881

https://pubmed.ncbi.nlm.nih.gov/34123447/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210614150933&v=2.14.4

TITLE:
Visual Snow-Like Symptoms and Posterior Uveitis following COVID-19 Infection

DESCRIPTION:
Visual snow (VS) is a neurologic condition consisting of a constant positive visual disturbance described as “static” with diagnosis requiring exclusion of competing neurologic and ophthalmologic disorders. The authors describe the first case of visual snow-like symptoms in a patient following coronavirus disease 2019 (COVID-19) infection. He was found to have a transient subtle mild inflammatory reaction in the vitreous and optic nerve edema which resolved, but the VS persisted. Our findings…

PMID:
pubmed:34123447

DATE FOUND:
06/14/21 03:09PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/34123447/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210614150933&v=2.14.4

https://pubmed.ncbi.nlm.nih.gov/33979006/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210512200942&v=2.14.4

TITLE:
Migraine prevalence in visual snow with prior illicit drug use (Hallucinogen Persisting Perception Disorder) versus without

DESCRIPTION:
CONCLUSIONS: While none of the HPPD participants had migraine, over half of the visual snow controls without prior use of illicit drugs had migraine. This suggests that at least partly different pathophysiological factors play a role in both disorders. Users of ecstasy and other hallucinogens should be warned of the risk of visual snow. Further studies are needed to enhance understanding of the underlying neurobiology of HPPD and VSS to come to better management of these conditions.

PMID:
pubmed:33979006

DATE FOUND:
05/12/21 08:09PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/33979006/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210512200942&v=2.14.4

https://pubmed.ncbi.nlm.nih.gov/33960084/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210507140529&v=2.14.4

TITLE:
White matter abnormalities in a patient with Visual Snow syndrome: new evidence from a Diffusion tensor imaging study

DESCRIPTION:
CONCLUSION: This VSS patient displayed multiple, bilateral white matter changes in the temporo-parieto-occipital junction in white matter pathways related to vision. We encourage the study of white matter pathology using DTI in complex neurological syndromes including VSS.

PMID:
pubmed:33960084

DATE FOUND:
05/07/21 02:05PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/33960084/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210507140529&v=2.14.4

https://www.nature.com/articles/s41598-021-88788-2

https://www.nature.com/articles/s41598-021-88788-2

Eye movement characteristics provide an objective measure of visual processing changes in patients with visual snow syndrome
Emma J. Solly, Meaghan Clough, Allison M. McKendrick, Paige Foletta, Owen B. White & Joanne Fielding

https://pubmed.ncbi.nlm.nih.gov/33950282/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210505202030&v=2.14.4

TITLE:
Visual snow syndrome – a pixelated vision

DESCRIPTION:
No abstract

PMID:
pubmed:33950282

DATE FOUND:
05/05/21 08:20PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/33950282/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210505202030&v=2.14.4

https://pubmed.ncbi.nlm.nih.gov/34017304/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210521190437&v=2.14.4

TITLE:
Magnetic Suppression of Perceptual Accuracy Is Not Reduced in Visual Snow Syndrome

DESCRIPTION:
Objective: Patients with visual snow syndrome (VSS) suffer from continuous (“TV snow-like”) visual disturbance of unknown pathoetiology. In VSS, changes in cortical excitability in the primary visual cortex and the visual association cortex are discussed, with recent imaging studies tending to point to higher-order visual areas. Migraine, especially migraine with aura, is a common comorbidity. In chronic migraine and episodic migraine with aura but not in episodic migraine without aura, a…

PMID:
pubmed:34017304

DATE FOUND:
05/21/21 07:04PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/34017304/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210521190437&v=2.14.4

https://pubmed.ncbi.nlm.nih.gov/32235228/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210223145155&v=2.14.2

TITLE:
Not All That Flickers Is Snow

DESCRIPTION:
A woman presented with bilateral visual disturbances that had been diagnosed as visual snow. Dilated ophthalmic examination and multimodal imaging were strongly suggestive of birdshot chorioretinopathy, meriting initiation of systemic immunomodulatory therapy. Visual snow requires a thorough ophthalmologic exam to exclude other ocular diseases.

PMID:
pubmed:32235228

DATE FOUND:
02/23/21 02:53PM

LINK / URL:
https://pubmed.ncbi.nlm.nih.gov/32235228/?utm_source=Other&utm_medium=rss&utm_campaign=None&utm_content=14czX-i9THTbCLiShSwLmfPkYONZQXBzqdieEHoJtKGcAAzgP4&fc=None&ff=20210223145155&v=2.14.2

https://www.ncbi.nlm.nih.gov/pubmed/33615842?dopt=Abstract

TITLE:
Two hundred and forty-eight cases of visual snow: A review of potential inciting events and contributing comorbidities.

DESCRIPTION:
Related Articles

Two hundred and forty-eight cases of visual snow: A review of potential inciting events and contributing comorbidities.

Cephalalgia. 2021 Feb 20;:333102421996355

Authors: Mehta DG, Garza I, Robertson CE

Abstract

OBJECTIVE: To review characteristics and outcomes of all cases of visual snow seen at our institution, with attention to possible triggering events or comorbidities.

METHODS: This is a retrospective case series of patients seen at our tertiary care center from January 1994 to January 2020. Charts were reviewed if they contained the term “visual snow”.

RESULTS: Of the 449 charts reviewed, 248 patients described seeing visual snow in part or all of their vision. Thirty-eight reported transient visual snow as their typical migraine aura. Of the remaining 210 patients, 89 were reported to have either an inciting event or contributing comorbidity for their visual snow symptoms, including: Post-concussion (n = 15), dramatic change in migraine or aura (n = 14), post-infection (n = 13), hallucinogen persisting perception disorder (n = 10), ocular abnormalities (n = 7), idiopathic intracranial hypertension (n = 4), neoplastic (n = 1), and posterior cortical atrophy (n = 1). Some patients had partial improvement with benzodiazepines (n = 6), lamotrigine (n = 5), topiramate (n = 3) and acetazolamide (n = 3). Presenting characteristics were similar, but patients with visual snow attributed to an inciting event or contributing comorbidity were more likely to have some improvement in their symptoms by last follow-up compared to spontaneous visual snow (p < .001). CONCLUSIONS: Though most cases of visual snow are spontaneous, potential secondary causes should be recognized by clinicians. Patients who develop visual snow after an inciting event or related to an underlying comorbidity may have a better prognosis than those in whom it develops spontaneously. In select cases, treatment of the suspected underlying cause may significantly alleviate the otherwise typical intractable visual disturbances associated with visual snow. PMID: 33615842 [PubMed - as supplied by publisher] PMID: PubMed:33615842 DATE FOUND: 02/23/21 06:00AM LINK / URL: https://www.ncbi.nlm.nih.gov/pubmed/33615842?dopt=Abstract

https://pubmed.ncbi.nlm.nih.gov/33435707/

Occipital ischaemic stroke after visual snow phenomenon – a case report

https://www.ncbi.nlm.nih.gov/pubmed/33328934?dopt=Abstract

TITLE:
Abnormal Connectivity and Brain Structure in Patients With Visual Snow.

DESCRIPTION:
Related Articles

Abnormal Connectivity and Brain Structure in Patients With Visual Snow.

Front Hum Neurosci. 2020;14:582031

Authors: Aldusary N, Traber GL, Freund P, Fierz FC, Weber KP, Baeshen A, Alghamdi J, Saliju B, Pazahr S, Mazloum R, Alshehri F, Landau K, Kollias S, Piccirelli M, Michels L

Abstract

Objective: Visual snow (VS) is a distressing, life-impacting condition with persistent visual phenomena. VS patients show cerebral hypermetabolism within the visual cortex, resulting in altered neuronal excitability. We hypothesized to see disease-dependent alterations in functional connectivity and gray matter volume (GMV) in regions associated with visual perception.

Methods: Nineteen patients with VS and 16 sex- and age-matched controls were recruited. Functional magnetic resonance imaging (fMRI) was applied to examine resting-state functional connectivity (rsFC). Volume changes were assessed by means of voxel-based morphometry (VBM). Finally, we assessed associations between MRI indices and clinical parameters.

Results: Patients with VS showed hyperconnectivity between extrastriate visual and inferior temporal brain regions and also between prefrontal and parietal (angular cortex) brain regions (p < 0.05, corrected for age and migraine occurrence). In addition, patients showed increased GMV in the right lingual gyrus (p < 0.05 corrected). Symptom duration positively correlated with GMV in both lingual gyri (p < 0.01 corrected). Conclusion: This study found VS to be associated with both functional and structural changes in the early and higher visual cortex, as well as the temporal cortex. These brain regions are involved in visual processing, memory, spatial attention, and cognitive control. We conclude that VS is not just confined to the visual system and that both functional and structural changes arise in VS patients, be it as an epiphenomenon or a direct contributor to the pathomechanism of VS. These in vivo neuroimaging biomarkers may hold potential as objective outcome measures of this so far purely subjective condition. PMID: 33328934 [PubMed] PMID: PubMed:33328934 DATE FOUND: 12/18/20 06:03AM LINK / URL: https://www.ncbi.nlm.nih.gov/pubmed/33328934?dopt=Abstract

https://thejcn.com/DOIx.php?id=10.3988/jcn.2020.16.4.646

https://www.ncbi.nlm.nih.gov/pubmed/33029971?dopt=Abstract

TITLE:
Neuro-ophthalmologic Findings in Visual Snow Syndrome.

DESCRIPTION:
Neuro-ophthalmologic Findings in Visual Snow Syndrome.

J Clin Neurol. 2020 Oct;16(4):646-652

Authors: Yoo YJ, Yang HK, Choi JY, Kim JS, Hwang JM

Abstract

BACKGROUND AND PURPOSE: The findings of ophthalmic examinations have not been systematically investigated in visual snow syndrome. This study reviewed the abnormal neuro-ophthalmologic findings in a patient cohort with symptoms of visual snow syndrome.

METHODS: We retrospectively reviewed 28 patients who were referred for symptoms of visual snow to a tertiary referral hospital from November 2016 to October 2019. We defined the findings of best corrected visual acuity (BCVA), visual field testing, pupillary light reflex, contrast sensitivity, full-field and multifocal electroretinography, and optical coherence tomography.

RESULTS: Twenty patients (71%) were finally diagnosed as visual snow syndrome. Their additional visual symptoms included illusionary palinopsia (61%), enhanced entoptic phenomenon (65%), disturbance of night vision (44%), and photophobia (65%). A history of migraine was identified in ten patients (50%). The mean BCVA was less than 0.1 logarithm of the minimum angle of resolution, and electrophysiology showed normal retinal function in all patients. Contrast sensitivity was decreased in two of the seven patients tested. Medical treatment was applied to five patients which all turned out to be ineffective. Among the eight patients who were excluded, one was diagnosed with rod-cone dystrophy and another with idiopathic intracranial hypertension.

CONCLUSIONS: Neuro-ophthalmologic findings are mostly normal in patients with visual snow syndrome. Retinal or neurological diseases must be excluded as possible causes of visual snow.

PMID: 33029971 [PubMed]

PMID:
PubMed:33029971

DATE FOUND:
10/09/20 06:02AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/33029971?dopt=Abstract

https://www.nature.com/articles/s41598-020-69705-5

Time-dependent branching processes: a model of oscillating neuronal avalanches
Johannes Pausch, Rosalba Garcia-Millan & Gunnar Pruessner
Scientific Reports volume 10, Article number: 13678 (2020)

https://journals.sagepub.com/doi/10.1177/0333102420950454

https://www.ncbi.nlm.nih.gov/pubmed/32791921?dopt=Abstract

TITLE:
[123I]-IMP single-photon emission computed tomography imaging in visual snow syndrome: A case series.

DESCRIPTION:
Related Articles

[123I]-IMP single-photon emission computed tomography imaging in visual snow syndrome: A case series.

Cephalalgia. 2020 Aug 13;:333102420950454

Authors: Shibata M, Tsutsumi K, Iwabuchi Y, Kameyama M, Takizawa T, Nakahara T, Fujiwara H, Jinzaki M, Nakahara J, Dodick DW

Abstract

BACKGROUND: Visual snow syndrome (VSS) is a neurological condition characterized by persistent flickering dots in the visual fields, palinopsia, enhanced entoptic phenomenon, photophobia, and nyctalopia. Neuroimaging evidence supports the role of the visual association cortex in visual snow syndrome.Case series: We provided clinical care to three patients with visual snow syndrome, in whom [123I]-IMP single-photon emission computed tomography (SPECT) imaging was performed. Case 1 was a 21-year-old male with a past history of migraine with aura who exhibited visual snow and entoptic phenomenon. In this patient, [123I]-IMP SPECT imaging revealed right occipital and temporal hypoperfusion with a distribution matching the ventral visual stream. [123I]-IMP SPECT imaging detected only mild bilateral frontal hypoperfusion in Case 2 and no overt abnormalities in Case 3.

CONCLUSION: Although visual snow syndrome seems to be a heterogenous condition, our observations indicate that abnormal visual processing within the ventral visual stream may play a role in the pathogenesis of this condition.

PMID: 32791921 [PubMed – as supplied by publisher]

PMID:
PubMed:32791921

DATE FOUND:
08/15/20 06:02AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32791921?dopt=Abstract

https://n.neurology.org/content/early/2020/08/05/WNL.0000000000010530

https://www.ncbi.nlm.nih.gov/pubmed/32759201?dopt=Abstract

TITLE:
Occipital cortex and cerebellum grey matter changes in visual snow syndrome.

DESCRIPTION:
Related Articles

Occipital cortex and cerebellum grey matter changes in visual snow syndrome.

Neurology. 2020 Aug 05;:

Authors: Puledda F, Bruchhage M, O’Daly O, Ffytche D, Williams SCR, Goadsby PJ

Abstract

OBJECTIVE: To determine whether regional grey and white matter differences characterize the brain of patients with visual snow syndrome, a newly defined neurologic condition, we used a voxel-based morphometry approach.

METHODS: In order to investigate directly whole brain morphology, we performed a magnetic resonance imaging study on patients (n = 24) with visual snow syndrome and on age- and gender matched (n = 24) healthy volunteers. Voxel-based morphometry was used to determine volumetric differences in visual snow subjects. We further analysed cerebellar anatomy directly using the high-resolution spatially unbiased atlas template of the cerebellum.

RESULTS: Compared to healthy controls, patients with visual snow syndrome had increased grey matter volume in the left primary and secondary visual cortices, the left visual motion area V5 and the left cerebellar crus I/lobule VI area. These anatomical alterations could not be explained by clinical features of the condition.

CONCLUSION: We conclude that patients with visual snow syndrome have subtle, yet significant neuroanatomical differences in key visual and lateral cerebellar areas, which may in part explain the pathophysiologic basis of the disorder.

PMID: 32759201 [PubMed – as supplied by publisher]

PMID:
PubMed:32759201

DATE FOUND:
08/08/20 06:00AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32759201?dopt=Abstract

https://n.neurology.org/content/early/2020/07/16/WNL.0000000000010372

https://www.ncbi.nlm.nih.gov/pubmed/32675081?dopt=Abstract

TITLE:
Ocular motor measures of visual processing changes in visual snow syndrome.

DESCRIPTION:
Related Articles

Ocular motor measures of visual processing changes in visual snow syndrome.

Neurology. 2020 Jul 16;:

Authors: Solly EJ, Clough M, McKendrick AM, Foletta P, White OB, Fielding J

Abstract

OBJECTIVE: To determine whether changes to cortical processing of visual information can be objectively evaluated using three simple ocular motor tasks to measure performance in patients with visual snow syndrome (VSS).

METHODS: Sixty four patients with VSS (32 with migraine and 32 with no migraine), and 23 controls participated. Three ocular motor tasks were included: prosaccade (PS), antisaccade (AS), and interleaved antisaccade-prosaccade (AS-PS) tasks. All these tasks have been used extensively in both neurologically healthy and diseased states.

RESULTS: We demonstrated that, compared to controls, the VSS group generated significantly shortened PS latencies (p = .029) and an increased rate of AS errors (p = .001), irrespective of the demands placed on visual processing (i.e., task context). Switch costs, a feature of the AS-PS task, were comparable across groups, and a significant correlation was found between shortened PS latencies and increased AS error rates for VSS patients (r = .404).

CONCLUSION: We identified objective and quantifiable measures of visual processing changes in patients with VSS. The absence of any additional switch cost on the AS-PS task in VSS suggests that the PS latency and AS error differences are attributable to a speeded PS response rather than to impaired executive processes more commonly implicated in poorer AS performance. We propose that this combination of latency and error deficits, in conjunction with intact switching performance will provide a VS behavioural signature that contributes to our understanding of VSS and may assist in determining the efficacy of therapeutic interventions.

PMID: 32675081 [PubMed – as supplied by publisher]

PMID:
PubMed:32675081

DATE FOUND:
07/18/20 06:03AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32675081?dopt=Abstract

https://onlinelibrary.wiley.com/doi/abs/10.1111/ene.14436

https://www.ncbi.nlm.nih.gov/pubmed/32652792?dopt=Abstract

TITLE:
Visual snow syndrome: is it normal or a disorder – and what to do with patients?

DESCRIPTION:
Visual snow syndrome: is it normal or a disorder – and what to do with patients?

Eur J Neurol. 2020 Jul 11;:

Authors: Schankin CJ, Puledda F, Goadsby PJ

Abstract

Recently in the journal, epidemiological data are presented on visual snow syndrome (VSS) using a crowdsourcing online platform [1]. The authors applied criteria for VSS to a sample of people matched for age, sex, and ethnicity to United Kingdom census data. Further, they assessed frequent headache lasting longer than 4 hours, which was interpreted as migraine, and neurological symptoms during headache, interpreted as aura.

PMID: 32652792 [PubMed – as supplied by publisher]

PMID:
PubMed:32652792

DATE FOUND:
07/12/20 06:03AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32652792?dopt=Abstract

https://www.sciencedirect.com/science/article/pii/S0079612320300625?via%3Dihub

Insights into pathophysiology and treatment of visual snow syndrome: A systematic review
Author links open overlay panelOzanErenaChristoph J.Schankinb
a
Department of Neurology, LMU Munich, University Hospital—Großhadern, Munich, Germany
b
Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
Received 4 March 2020, Revised 25 April 2020, Accepted 1 May 2020, Available online 15 June 2020.

https://3002a505d4f8666b1f13-6d0524d9c8a5052ce15209ae3ecb39a3.ssl.cf1.rackcdn.com//1331558-1590516001.pdf

https://headachejournal.onlinelibrary.wiley.com/doi/abs/10.1111/head.13893

Visual Snow Case Series: Review of 248 Cases with Attention to Underlying Causes or Inciting Events

Ghislaine L Traber; Njoud Aldusary; Patrick Freund; Fabienne C. Fierz; Konrad P Weber; Marco Piccirelli; Arvwa Baeshen; Jamaan Alghamdi; Bujar Saliju; Shila Pazahr; R Mazloum; Fahad Alshehri; Klara Landau; Spyros Kollias; Lars Michels

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OPEN ACCESS
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 3387.

Ghislaine L Traber, Njoud Aldusary, Patrick Freund, Fabienne C. Fierz, Konrad P Weber, Marco Piccirelli, Arvwa Baeshen, Jamaan Alghamdi, Bujar Saliju, Shila Pazahr, R Mazloum, Fahad Alshehri, Klara Landau, Spyros Kollias, Lars Michels; Visual snow patients show functional hyperconnectivity and structural abnormalities of brain regions involved in visual processing. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3387.

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

https://www.karger.com/Article/FullText/508602

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315196/

https://www.ncbi.nlm.nih.gov/pubmed/32595484?dopt=Abstract

TITLE:
Visual Snow: A Case Series from Israel.

DESCRIPTION:
Related Articles

Visual Snow: A Case Series from Israel.

Case Rep Ophthalmol. 2020 May-Aug;11(2):205-211

Authors: Berkowitz E, River Y, Digre K, Tiosano B, Kesler A

Abstract

Our aim was to examine the symptoms and clinical characteristics of visual snow in a group of 6 patients from a Department of Ophthalmology and a Department of Neurology. Visual snow is now recognized as a true physiological disorder. Previously, physicians unaware of this syndrome may have misinterpreted its symptoms as a persistent visual aura. By promoting awareness of this syndrome, greater quantitative and qualitative research may expand our understanding and treatment of this disorder.

PMID: 32595484 [PubMed]

PMID:
PubMed:32595484

DATE FOUND:
07/01/20 06:05AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32595484?dopt=Abstract

M. Graber, P.J. Goadsby, A. Scutelnic, C. Schankin

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EPR1103
ePresentation Sessions | 162
2020 European Journal of Neurology, 27 (Suppl. 1 (Suppl. 1), 103–522

Source: https://www.ean.org/fileadmin/user_upload/ean/congress-2020/Present/Abstracts/02_EAN_Journal_2020_ePresentation_Sessions.pdf

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Copyright © 2020 European Journal of Neurology

https://www.nature.com/articles/s41586-020-2319-4

Feedback generates a second receptive field in neurons of the visual cortex

https://www.nature.com/articles/s41598-020-62734-0

Synaptic ribbons foster active zone stability and illumination-dependent active zone enrichment of RIM2 and Cav1.4 in photoreceptor synapses

https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awaa053/5811372

https://academic.oup.com/brain/article/143/4/1106/5811372

https://www.ncbi.nlm.nih.gov/pubmed/32211752?dopt=Abstract

TITLE:
Structural and functional footprint of visual snow syndrome.

DESCRIPTION:
Related Articles

Structural and functional footprint of visual snow syndrome.

Brain. 2020 Mar 24;:

Authors: Schankin CJ, Maniyar FH, Chou DE, Eller M, Sprenger T, Goadsby PJ

Abstract

Patients with visual snow syndrome suffer from a continuous pan-field visual disturbance, additional visual symptoms, tinnitus, and non-perceptional symptoms. The pathophysiology of visual symptoms might involve dysfunctional visual cortex. So far, the extra-visual system has not been investigated. We aimed at identifying structural and functional correlates for visual and non-visual symptoms in visual snow syndrome. Patients were compared to age- and sex-matched controls using 18F-2-fluoro-2-deoxy-d-glucose PET (n = 20 per group) and voxel-based morphometry (n = 17 per group). Guided by the PET results, region of interest analysis was done in voxel-based morphometry to identify structural-functional correspondence. Grey matter volume was assessed globally. Patients had corresponding hypermetabolism and cortical volume increase in the extrastriate visual cortex at the junction of the right lingual and fusiform gyrus. There was hypometabolism in the right superior temporal gyrus and the left inferior parietal lobule. Patients had grey matter volume increases in the temporal and limbic lobes and decrease in the superior temporal gyrus. The corresponding structural and functional alterations emphasize the relevance of the visual association cortex for visual snow syndrome. The broad structural and functional footprint, however, confirms the clinical impression that the disorder extends beyond the visual system.

PMID: 32211752 [PubMed – as supplied by publisher]

PMID:
PubMed:32211752

DATE FOUND:
03/27/20 03:26PM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32211752?dopt=Abstract

https://journals.lww.com/jneuro-ophthalmology/Abstract/publishahead/Not_All_That_Flickers_Is_Snow.99020.aspx

https://www.ncbi.nlm.nih.gov/pubmed/32235228?dopt=Abstract

TITLE:
Not All That Flickers Is Snow.

DESCRIPTION:
Related Articles

Not All That Flickers Is Snow.

J Neuroophthalmol. 2020 Mar 24;:

Authors: Patel RC, Vitale AT, Creel DJ, Digre KB

Abstract

A woman presented with bilateral visual disturbances that had been diagnosed as visual snow. Dilated ophthalmic examination and multimodal imaging were strongly suggestive of birdshot chorioretinopathy, meriting initiation of systemic immunomodulatory therapy. Visual snow requires a thorough ophthalmologic exam to exclude other ocular diseases.

PMID: 32235228 [PubMed – as supplied by publisher]

PMID:
PubMed:32235228

DATE FOUND:
04/03/20 06:02AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32235228?dopt=Abstract

https://onlinelibrary.wiley.com/doi/full/10.1002/acn3.50986

https://www.ncbi.nlm.nih.gov/pubmed/32154676?dopt=Abstract

TITLE:
Insular and occipital changes in visual snow syndrome: a BOLD fMRI and MRS study.

DESCRIPTION:
Insular and occipital changes in visual snow syndrome: a BOLD fMRI and MRS study.

Ann Clin Transl Neurol. 2020 Mar 10;:

Authors: Puledda F, Ffytche D, Lythgoe DJ, O’Daly O, Schankin C, Williams SCR, Goadsby PJ

Abstract

OBJECTIVE: To investigate the pathophysiology of visual snow (VS), through a combined functional neuroimaging and magnetic resonance spectroscopy (1 H-MRS) approach.

METHODS: We applied a functional MRI block-design protocol studying the responses to a visual stimulation mimicking VS, in combination with 1 H-MRS over the right lingual gyrus, in 24 patients with VS compared to an equal number of age- and gender-matched healthy controls.

RESULTS: We found reduced BOLD responses to the visual stimulus with respect to baseline in VS patients compared to controls, in the left (k = 291; P = 0.025; peak MNI coordinate [-34 12 -6]) and right (k = 100; P = 0.003; peak MNI coordinate [44 14 -2]) anterior insula. Our spectroscopy analysis revealed a significant increase in lactate concentrations in patients with respect to controls (0.66 ± 0.9 mmol/L vs. 0.07 ± 0.2 mmol/L; P < 0.001) in the right lingual gyrus. In this area, there was a significant negative correlation between lactate concentrations and BOLD responses to visual stimulation (P = 0.004; r = -0.42), which was dependent on belonging to the patient group. INTERPRETATION: As shown by our BOLD analysis, VS is characterized by a difference in bilateral insular responses to a visual stimulus mimicking VS itself, which could be due to disruptions within the salience network. Our results also suggest that patients with VS have a localized disturbance in extrastriate anaerobic metabolism, which may in turn cause a decreased metabolic reserve for the regular processing of visual stimuli. PMID: 32154676 [PubMed - as supplied by publisher] PMID: PubMed:32154676 DATE FOUND: 03/11/20 06:01AM LINK / URL: https://www.ncbi.nlm.nih.gov/pubmed/32154676?dopt=Abstract

https://www.nature.com/articles/s41582-020-0324-8

https://www.ncbi.nlm.nih.gov/pubmed/32071423?dopt=Abstract

TITLE:
Shedding new light on visual snow syndrome.

DESCRIPTION:
Related Articles

Shedding new light on visual snow syndrome.

Nat Rev Neurol. 2020 Feb 18;:

Authors: Wood H

PMID: 32071423 [PubMed – as supplied by publisher]

PMID:
PubMed:32071423

DATE FOUND:
02/20/20 06:03AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/32071423?dopt=Abstract

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0228937

Additive effect of contrast and velocity suggests the role of strong excitatory drive in suppression of visual gamma response

https://journals.lww.com/co-neurology/Abstract/2020/02000/Visual_snow_syndrome__a_review_on_diagnosis,.13.aspx

https://europepmc.org/article/med/31714263

Visual snow syndrome: a review on diagnosis, pathophysiology, and treatment.

https://onlinelibrary.wiley.com/doi/abs/10.1111/ene.14150

https://www.ncbi.nlm.nih.gov/pubmed/31999855?dopt=Abstract

Prevalence of visual snow syndrome in the UK is around 2%

TITLE:
Prevalence of visual snow syndrome in the UK.

DESCRIPTION:
Prevalence of visual snow syndrome in the UK.

Eur J Neurol. 2020 Jan 30;:

Authors: Kondziella D, Olsen MH, Dreier JP

Abstract

BACKGROUND: Visual snow syndrome is a recently described condition of unknown prevalence. We investigated the prevalence in a representative population sample from the UK and tested the hypothesis that visual snow syndrome is associated with young age, headache, tinnitus and mood impairment.

METHODS: Using a crowdsourcing platform, we recruited a representative sample of 1015 adult laypeople from the UK, matched for age, gender and ethnicity according to national census data. Participants were unprimed, i.e. were inquired about the “frequency of certain medical conditions” but not “visual snow syndrome”.

RESULTS: Thirty-eight of 1015 participants reported symptoms compatible with visual snow (3.7%, 95% CI 2.7-5.2), and 22/1015 met criteria for visual snow syndrome (2.2%, 95% CI 1.4-3.3). Female-to-male ratio for visual snow syndrome was 1.6:1. Subjects with visual snow syndrome were older (50.6 ±14 years) than the population mean (44.8 ±15 years), albeit not statistically different (p=0.06). Of 22 participants with visual snow syndrome, 16 had mood symptoms (72.7%; p=0.01), 13 had headache (54.5%, p=0.06), including 5 with visual migraine aura (22.7%, p=0.15), and 13 had tinnitus (59.1%, p<0.001). No participant had diabetes or a cleft lip (control questions). Following a multivariable regression analysis to adjust for age and gender, only the association between visual snow syndrome and tinnitus remained significant (OR 3.93, 95% CI 1.63-9.9; p=0.003). CONCLUSIONS: The UK prevalence of visual snow syndrome is around 2%. We confirmed an association with tinnitus, but unprimed laypeople with visual snow syndrome are on average older than those seeking medical attention. PMID: 31999855 [PubMed - as supplied by publisher] PMID: PubMed:31999855 DATE FOUND: 01/31/20 06:02AM LINK / URL: https://www.ncbi.nlm.nih.gov/pubmed/31999855?dopt=Abstract

https://n.neurology.org/content/early/2020/01/16/WNL.0000000000008913

https://pubmed.ncbi.nlm.nih.gov/31949088-visual-snow-are-we-beginning-to-see-the-light/

Visual Snow: Are We Beginning to See the Light?

https://n.neurology.org/content/early/2020/01/15/WNL.0000000000008909

https://www.ncbi.nlm.nih.gov/pubmed/31941797?dopt=Abstract

TITLE:
Visual snow syndrome: A clinical and phenotypical description of 1,100 cases.

DESCRIPTION:
Related Articles

Visual snow syndrome: A clinical and phenotypical description of 1,100 cases.

Neurology. 2020 Jan 15;:

Authors: Puledda F, Schankin C, Goadsby PJ

Abstract

OBJECTIVE: To validate the current criteria of visual snow and to describe its common phenotype using a substantial clinical database.

METHODS: We performed a web-based survey of patients with self-assessed visual snow (n = 1,104), with either the complete visual snow syndrome (n = 1,061) or visual snow without the syndrome (n = 43). We also describe a population of patients (n = 70) with possible hallucinogen persisting perception disorder who presented clinically with visual snow syndrome.

RESULTS: The visual snow population had an average age of 29 years and had no sex prevalence. The disorder usually started in early life, and ≈40% of patients had symptoms for as long as they could remember. The most commonly experienced static was black and white. Floaters, afterimages, and photophobia were the most reported additional visual symptoms. A latent class analysis showed that visual snow does not present with specific clinical endophenotypes. Severity can be classified by the amount of visual symptoms experienced. Migraine and tinnitus had a very high prevalence and were independently associated with a more severe presentation of the syndrome.

CONCLUSIONS: Clinical characteristics of visual snow did not differ from the previous cohort in the literature, supporting validity of the current criteria. Visual snow likely represents a clinical continuum, with different degrees of severity. On the severe end of the spectrum, it is more likely to present with its common comorbid conditions, migraine and tinnitus. Visual snow does not depend on the effect of psychotropic substances on the brain.

PMID: 31941797 [PubMed – as supplied by publisher]

PMID:
PubMed:31941797

DATE FOUND:
01/17/20 04:38PM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/31941797?dopt=Abstract

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923266/#s7title

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923266/

https://www.frontiersin.org/articles/10.3389/fneur.2019.01325/full

https://www.ncbi.nlm.nih.gov/pubmed/31920945?dopt=Abstract

TITLE:
Imaging the Visual Network in the Migraine Spectrum.

DESCRIPTION:
Related Articles

Imaging the Visual Network in the Migraine Spectrum.

Front Neurol. 2019;10:1325

Authors: Puledda F, Ffytche D, O’Daly O, Goadsby PJ

Abstract

The involvement of the visual network in migraine pathophysiology has been well-known for more than a century. Not only is the aura phenomenon linked to cortical alterations primarily localized in the visual cortex; but also migraine without aura has shown distinct dysfunction of visual processing in several studies in the past. Further, the study of photophobia, a hallmark migraine symptom, has allowed unraveling of distinct connections that link retinal pathways to the trigeminovascular system. Finally, visual snow, a recently recognized neurological disorder characterized by a continuous visual disturbance, is highly comorbid with migraine and possibly shares with it some common pathophysiological mechanisms. Here, we review the most relevant neuroimaging literature to date, considering studies that have either attempted to investigate the visual network or have indirectly shown visual processing dysfunctions in migraine. We do this by taking into account the broader spectrum of migrainous biology, thus analyzing migraine both with and without aura, focusing on light sensitivity as the most relevant visual symptom in migraine, and finally analyzing the visual snow syndrome. We also present possible hypotheses on the underlying pathophysiology of visual snow, for which very little is currently known.

PMID: 31920945 [PubMed]

PMID:
PubMed:31920945

DATE FOUND:
01/11/20 06:04AM

LINK / URL:
https://www.ncbi.nlm.nih.gov/pubmed/31920945?dopt=Abstract

https://jamanetwork.com/journals/jamaneurology/article-abstract/2755346

https://www.ncbi.nlm.nih.gov/pubmed/31764944?dopt=Abstract

Episodic Visual Snow Associated With Migraine Attacks.

JAMA Neurol

Related Articles

Episodic Visual Snow Associated With Migraine Attacks.

JAMA Neurol. 2019 Nov 25;:

Authors: Hodak J, Fischer U, Bassetti CLA, Schankin CJ

PMID: 31764944 [PubMed – as supplied by publisher]

PubMed:31764944

https://www.tandfonline.com/doi/abs/10.1080/10550887.2019.1673655?journalCode=wjad20

https://www.ncbi.nlm.nih.gov/pubmed/31613183

Hallucinogen persisting perception disorder: A literature review and three case reports

https://www.cell.com/current-biology/fulltext/S0960-9822(19)31020-6

Functionally Distinct Gamma Range Activity Revealed by Stimulus Tuning in Human Visual Cortex

https://f1000research.com/articles/8-1219/v1

https://www.ncbi.nlm.nih.gov/pubmed/31448081?dopt=Abstract

Symptoms related to the visual system in migraine.

F1000Res

Related Articles

Symptoms related to the visual system in migraine.

F1000Res. 2019;8:

Authors: van Dongen RM, Haan J

Abstract

Migraine is a common headache disorder characterized by often-severe headaches that may be preceded or accompanied by a variety of visual symptoms. Although a typical migraine aura is not difficult to diagnose, patients with migraine may report several other visual symptoms, such as prolonged or otherwise atypical auras, “visual blurring”, “retinal migraine”, “ophthalmoplegic migraine”, photophobia, palinopsia, and “visual snow”. Here, we provide a short overview of these symptoms and what is known about the relationship with migraine pathophysiology. For some symptoms, the association with migraine is still debated; for other symptoms, recent studies indicate that migraine mechanisms play a role.

PMID: 31448081 [PubMed – in process]

PubMed:31448081

https://www.pnas.org/content/116/32/16056

Prestimulus feedback connectivity biases the content of visual experiences

https://nn.neurology.org/content/6/5/e592

https://www.ncbi.nlm.nih.gov/pubmed/31355325?dopt=Abstract

Novel clinical features of glycine receptor antibody syndrome: A series of 17 cases.

Neurol Neuroimmunol Neuroinflamm

Novel clinical features of glycine receptor antibody syndrome: A series of 17 cases.

Neurol Neuroimmunol Neuroinflamm. 2019 Sep;6(5):e592

Authors: Piquet AL, Khan M, Warner JEA, Wicklund MP, Bennett JL, Leehey MA, Seeberger L, Schreiner TL, Paz Soldan MM, Clardy SL

Abstract

Objective: To describe novel clinical features of GlyRα1-IgG-positive patients.

Methods: Patients with a positive serum GlyRα1-IgG were identified during a 2-year period from July 2016 to December 2018 at 2 academic centers and followed prospectively. All patients in this series were evaluated in the Neuroimmunology and Autoimmune Neurology clinics at the University of Utah or the University of Colorado.

Results: Thirteen of 17 patients had phenotypes more typically associated with glutamic acid decarboxylase (GAD65) antibody syndromes, consisting of stiff-person syndrome (SPS) with parkinsonism or cerebellar signs. One patient with parkinsonism had a presentation similar to rapidly progressive multiple system atrophy with severe dysautonomia. Ten of 17 patients had various visual symptoms including visual snow, spider web-like images forming shapes and 3-dimensional images, palinopsia, photophobia, visual hallucinations, synesthesia, and intermittent diplopia. Three of 17 patients presented with primarily autoimmune epilepsy accompanied by psychiatric symptoms.

Conclusions: Clinicians should consider testing for GlyR antibodies in GAD65 antibody-negative or low-positive GAD65 antibody patients with SPS-like presentations, especially in the setting of atypical features such as visual disturbances, parkinsonism, or epilepsy.

PMID: 31355325 [PubMed – in process]

PubMed:31355325

https://n.neurology.org/content/early/2019/06/18/WNL.0000000000007825

https://www.ncbi.nlm.nih.gov/pubmed/31213497?dopt=Abstract

Treatment effects and comorbid diseases in 58 patients with visual snow.

Neurology

Related Articles

Treatment effects and comorbid diseases in 58 patients with visual snow.

Neurology. 2019 Jun 18;:

Authors: van Dongen RM, Waaijer LC, Onderwater GLJ, Ferrari MD, Terwindt GM

Abstract

OBJECTIVE: To evaluate pharmacologic treatment options for visual snow and to report prevalence of comorbid diseases.

METHODS: Medical charts of patients with a diagnosis of visual snow at the neurology outpatient clinic were reviewed on prescribed medication, and comorbid migraine, tinnitus, and psychiatric conditions including depression and anxiety.

RESULTS: From 2007 to 2018, 58 patients were diagnosed with visual snow. Comorbid migraine was present in 51.7% of patients, lifetime depression in 41.4%, and lifetime anxiety in 44.8%. Lamotrigine was prescribed most frequently (26/58) and resulted in partial remission of symptoms in 5/26 (19.2%). No patients reported complete remission. Adverse events occurred in 13/26 (50.0%) patients. None of the other prescribed drugs (valproate [n = 7], topiramate [n = 4], acetazolamide [n = 2], flunarizine [n = 1]) led to improvement except for topiramate in one patient, who discontinued, however, because of adverse events.

CONCLUSIONS: Of medication prescribed (lamotrigine, valproate, acetazolamide, flunarizine), only lamotrigine afforded some improvement in a small minority of patients. Migraine, depression, anxiety, and tinnitus were common comorbid diseases.

CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for some patients with visual snow, lamotrigine resulted in partial remission of symptoms.

PMID: 31213497 [PubMed – as supplied by publisher]

PubMed:31213497

https://ww5.aievolution.com/hbm1901/index.cfm?do=abs.viewAbs&abs=2590

Tracking functional and structural brain plasticity in patients with visual snow

https://www.ncbi.nlm.nih.gov/pubmed/31022065?dopt=Abstract

Neuro-Ophthalmic Symptoms of Primary Headache Disorders: Why the Patient With Headache May Present to Neuro-Ophthalmology.

J Neuroophthalmol

Neuro-Ophthalmic Symptoms of Primary Headache Disorders: Why the Patient With Headache May Present to Neuro-Ophthalmology.

J Neuroophthalmol. 2019 Apr 23;:

Authors: Smith SV

Abstract

BACKGROUND: Primary headache disorders can cause many ophthalmic symptoms that lead many patients to present for neuro-ophthalmic evaluation. Neuro-ophthalmologists frequently encounter these patients in clinical practice.

EVIDENCE ACQUISITION: A literature review was completed in PubMed using the following terms paired with “migraine” and “headache:” dry eye, eye pain, monocular diplopia, binocular diplopia, photophobia, visual field defect, tunnel vision, floaters, amaurosis fugax, transient visual obscuration, autonomic symptoms, anisocoria, visual snow, Alice in Wonderland syndrome, and palinopsia.

RESULTS: Patients with migraine experience a wide range of visual disturbances including aura and more complex perceptual abnormalities such as Alice in Wonderland syndrome and visual snow. Visual disturbances may consist of positive and/or negative phenomena and may be binocular or monocular. Migraine and other primary headache disorders can be associated with photophobia, eye pain, dry eye, autonomic features, and anisocoria.

CONCLUSIONS: Patients with primary headache disorders may experience a wide range of visual and ophthalmic symptoms. An understanding of the typical features of these disorders allows providers to help patients find appropriate treatment without unnecessary testing and to recognize when atypical presentations require additional evaluation.

PMID: 31022065 [PubMed – as supplied by publisher]

PubMed:31022065

https://n.neurology.org/content/92/15_Supplement/S20.005

Visual contrast threshold at 15 Hz is able to confirm visual snow syndrome in individual patients (S20.005)
Ozan Eren, Thomas Eggert, Ruth Ruscheweyh, Andreas Straube, Christoph Schankin
First published April 16, 2019
Added on July 10, 2020

https://www.sciencedirect.com/science/article/pii/S0967586819301389

https://www.ncbi.nlm.nih.gov/pubmed/30910546?dopt=Abstract

Visual snow: Not so benign.

J Clin Neurosci

Related Articles

Visual snow: Not so benign.

J Clin Neurosci. 2019 Mar 22;:

Authors: Chen BS, Lance S, Lallu B, Anderson NE

Abstract

Visual snow is the perception of flickering dots throughout the entire visual field and occurs with other symptoms of dysfunctional central sensory processing. We describe a patient who presented with visual snow, illusory visual motion, photopsia, and reduced night vision. He subsequently developed progressive cognitive impairment, myoclonus and ataxia. A diagnosis of sporadic Creutzfeldt-Jakob Disease was confirmed on post-mortem examination more than 49 months after symptom onset. The visual snow syndrome is typically benign, but our patient illustrates that occasionally it is the first manifestation of a serious brain disease. Careful application of the diagnostic criteria for the visual snow syndrome is important, particularly with the use of neuroimaging to exclude pathology in the occipital cortex.

PMID: 30910546 [PubMed – as supplied by publisher]

PubMed:30910546

https://www.ncbi.nlm.nih.gov/pubmed/30848479?dopt=Abstract

The Clinical Characteristics and Neurophysiological Assessments of the Occipital Cortex in Visual Snow Syndrome With or Without Migraine.

Headache

The Clinical Characteristics and Neurophysiological Assessments of the Occipital Cortex in Visual Snow Syndrome With or Without Migraine.

Headache. 2019 Mar 08;:

Authors: Yildiz FG, Turkyilmaz U, Unal-Cevik I

Abstract

OBJECTIVE: Visual snow syndrome (VS) is mainly characterized by flickering, little dots in both visual fields. The recognition of the clinical entity of VS has been increasing recently. Diagnosis is based on patient reports and not better accounted for by another diagnosis.

BACKGROUND: The exact pathophysiology of this syndrome is still unknown. In this study, our aim was to investigate the role of neurophysiological assessments of the occipital cortex in VS patients with (VSm ) or without migraine (VSwom ) and the healthy control (HC).

METHODS: To assess the occipital cortex hyperexcitability, we conducted a prospective, observational study to investigate the habituation/potentiation response by repetitive pattern reversal visual evoked potentials (rVEP) and examined the phosphene thresholds (PT) by transcranial magnetic stimulation in VS patients with or without migraine who were admitted to our tertiary headache clinic and the healthy control.

RESULTS: Twenty-nine volunteers were recruited. The VSm (n = 10), the VSwom (n = 7), and the HC group (n = 12) did not differ demographically. Flickering and floaters were reported in all VS patients and flickering in the dark was the most distressing symptomatology in both VS groups. Higher VAS scores for palinopsia (trailing), photophobia, and concentration difficulty were more frequently self-reported by VSm patients. The HC demonstrated habituation; however, there was loss of habituation response and decreased PTs in both groups of VS patients. The N1P1 VEP amplitude ratios of the 10th/1st block from right and left eye stimulation disclosed higher values (lack of habituation) in VSm (1.04 ± 0.2 and 1.06 ± 0.2) and the VSwom (1.05 ± 0.2 and 0.96 ± 0.08) patients compared to the healthy control (0.75 ± 0.1 and 0.79 ± 0.1), P = .002 from right eye and P = .003 from left eye. In the post hoc analysis the VS patients did not differ according to the presence of migraine from right or left eye stimulations (both P > .999). The left occipital cortex PTs were lower in VSm (58.00 ± 6.60) and VSwom (62.14 ± 11.53) and higher in the HC (71.33 ± 5.56) P = .009. In the post hoc analysis the VS patients did not differ according to the presence of migraine (P > .999). The right occipital cortex PTs were lower in VSm (60.30 ± 8.15) and VSwom (62.00 ± 10.95), higher in the HC (69.67 ± 8.04); however, statistically, groups did not differ (P = .087).

CONCLUSIONS: The loss of habituation and lower threshold for occipital cortex excitability were demonstrated electrophysiologically in VS patients. While statistically significant loss of habituation was seen in both VS patients (with or without migraine) in the right eye, statistically significant loss of habituation in the left eye and decreased threshold of left occipital cortex excitability was seen in visual snow with migraine patients. These findings may provide new insights on “visual snow” pathophysiology and serve as an objective and quantitative assessment tool in VS patients.

PMID: 30848479 [PubMed – as supplied by publisher]

PubMed:30848479

https://journals.lww.com/neurotodayonline/Fulltext/2019/01100/Visual_Snow_Is_a_Real_Neurological_Phenomenon.3.aspx

Visual Snow Is a Real Neurological Phenomenon Distinct from Migraine

https://www.ncbi.nlm.nih.gov/pubmed/30663293

[WHEN IT SNOWS ALL YEAR ROUND – VISUAL SNOW].

https://journals.lww.com/psychopharmacology/Citation/2018/12000/Hallucinogen_Persisting_Perception_Disorder_After.23.aspx

Hallucinogen Persisting Perception Disorder After Ibogaine Treatment for Opioid Dependence

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6865508/

Neural gain control measured through cortical gamma oscillations is associated with sensory sensitivity

https://journals.lww.com/jneuro-ophthalmology/Abstract/2018/12000/Visual_Snow___Visual_Misperception.20.aspx

https://www.ncbi.nlm.nih.gov/pubmed/30095537

Visual Snow: Visual Misperception.

White, Owen B., MD, PhD, FRACP; Clough, Meaghan, PhD; McKendrick, Allison M., PhD; Fielding, Joanne, PhD

Section Editor(s): Biousse, Valérie MD; Galetta, Steven MD

Journal of Neuro-Ophthalmology: December 2018 – Volume 38 – Issue 4 – p 514–521
doi: 10.1097/WNO.0000000000000702
State-of-the-Art Review
Abstract
Author Information
Article Metrics
Background: Visual snow (VS) is a constant visual disturbance described as flickering dots occupying the entire visual field. Recently, it was characterized as the defining feature of a VS syndrome (VSS), which includes palinopsia, photophobia, photopsias, entoptic phenomena, nyctalopia, and tinnitus. Sixty percent of patients with VSS also experience migraine, with or without aura. This entity often is considered psychogenic in nature, to the detriment of the patient’s best interests, but the high frequency of similar visual symptoms argues for an organic deficit. The purpose of this review is to clarify VSS as a true entity and elaborate the nature of individual symptoms and their relationship to each other.

Evidence Acquisition: The literature was reviewed with specific regard to the clinical presentation and psychophysical, neurophysiological, and functional imaging studies in patients with defined visual disturbances that comprise VSS.

Results: Consideration of the individual symptoms suggests that multiple factors are potentially involved in the development of VSS, including subcortical network malfunction and cortical hyperexcitation. Although there is substantial overlap between VSS and migraine syndromes in terms of co-occurring symptoms, both neurophysiological and neuroimaging studies provide substantial evidence of separate abnormalities of processing, supporting these as separate syndromes.

Conclusions: VSS is likely associated with either hyperactive visual cortices or, alternatively, impaired processing of simultaneous afferent information projecting to cortex. VSS likely results from widespread disturbance of sensory processing resulting in sensory misperception. There may be a number of syndromes associated with impaired sensory processing resulting in sensory misperception, including migraine, persistent perceptual postural dizziness, and tinnitus, which overlap with VSS. Elucidation of abnormality in one defined syndrome may provide a path forward for investigating all.

https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.25372

Evidence of dysfunction in the visual association cortex in visual snow syndrome

Ann Neurol. 2018 Dec;84(6):946-949. doi: 10.1002/ana.25372. Epub 2018 Nov 30.
Evidence of dysfunction in the visual association cortex in visual snow syndrome.
Eren O1, Rauschel V1, Ruscheweyh R1, Straube A1, Schankin CJ1,2.
Author information
Abstract
Patients with visual snow syndrome (VS) suffer from a debilitating continuous visual disturbance of unknown mechanism. The present study tested the hypothesis of dysfunctional visual processing using visual evoked potentials. Eighteen patients were compared to age-matched migraineurs (M) and healthy controls (C) using 2-way analysis of variance with group (VS, M, C) and gender as factors. Visual evoked potentials from patients with VS demonstrated increased N145 latency (in milliseconds, VS: 152.7 ± 7.9 vs M: 145.3 ± 9.8 vs C: 145.5 ± 9.4; F = 3.28; p = 0.046) and reduced N75-P100 amplitudes (in microvolts, VS: 7.4 ± 3.5 vs M: 12.5 ± 4.7 vs C: 10.8 ± 3.4; F = 3.16; p = 0.051). Dunnett post hoc analysis was significant for all comparisons between VS and controls. These findings are in agreement with the idea that the primary disturbance in VS is a dysfunction of the visual association cortex. Ann Neurol 2018;84:946-949.

© 2018 American Neurological Association.

PMID: 30383334 DOI: 10.1002/ana.25372

https://journals.sagepub.com/doi/full/10.1177/0333102418801648#_i29

Alterations in Regional Cerebral Blood (RCBF) in Visual Snow Assessed Using Arterial Spin-Labelled (ASL) Functional Magnetic Resonance Imagining (FMRI)

Experimental research
MTIS2018-153
ALTERATIONS IN REGIONAL CEREBRAL BLOOD (RCBF) IN VISUAL SNOW ASSESSED USING ARTERIAL SPIN-LABELLED (ASL) FUNCTIONAL MAGNETIC RESONANCE IMAGING (FMRI)
F. Puledda1,*, F. Zelaya2, C. Schankin3 and P. J. Goadsby1

Conclusion: Patients with visual snow present significant increase in blood flow in various brain regions, namely the cerebellum, cuneus, precuneus, insula, occipital and parietal cortices, both at baseline and when subject to a visual stimulus simulating the snow itself.

This study suggests that measures of regional CBF using ASL may provide a sensitive surrogate marker of differences in resting state neuronal activity, in subjects who experience visual snow syndrome. These results are consistent with those reported in previous investigations using Positron Emission Tomography.

https://journals.lww.com/jneuro-ophthalmology/Citation/2018/09000/The_Visual_Snow_Conference___May_5,_2018,.32.aspx

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

https://link.springer.com/article/10.1007%2Fs11910-018-0854-2

https://www.ncbi.nlm.nih.gov/pubmed/29934719

Visual Snow Syndrome: Proposed Criteria, Clinical Implications, and Pathophysiology.

http://n.neurology.org/content/90/15_Supplement/P4.129

Visual Snow Syndrome Successfully Treated with Lamotrigine: Case Report. (P4.129)

Perhaps the most important unmet need for the condition is a sufficient understanding of it to generate and test hypotheses about treatment.

https://journals.lww.com/co-neurology/Abstract/2018/02000/Visual_snow_syndrome___what_we_know_so_far.9.aspx

https://www.ncbi.nlm.nih.gov/pubmed/29140814

Visual snow syndrome: what we know so far.
Visual snow syndrome: what we know so far

Current Opinion in Neurology: February 2018 – Volume 31 – Issue 1 – p 52–58
doi: 10.1097/WCO.0000000000000523
NEURO-OPHTHALMOLOGY AND NEURO-OTOLOGY: Edited by José-Alain Sahel, Michael Strupp and David Zee
Abstract
Author Information
Article Metrics
Purpose of review We provide an overview of the neurological condition known as visual snow syndrome. Patients affected by this chronic disorder suffer with a pan-field visual disturbance described as tiny flickering dots, which resemble the static noise of an untuned television.

Recent findings The term ‘visual snow’ has only appeared in the medical literature very recently. The clinical features of the syndrome have now been reasonably described and the pathophysiology has begun to be explored. This review focuses on what is currently known about visual snow.

Summary Recent evidence suggests visual snow is a complex neurological syndrome characterized by debilitating visual symptoms. It is becoming better understood as it is systematically studied. Perhaps the most important unmet need for the condition is a sufficient understanding of it to generate and test hypotheses about treatment.

https://onlinelibrary.wiley.com/doi/abs/10.1111/head.13231

Antagonistic Relationship Between VEP Potentiation and Gamma Power in Visual Snow Syndrome.
Luna S1, Lai D1, Harris A1,2.
Author information
Abstract
OBJECTIVE:
Using a “double-pulse” adaptation paradigm, in which two stimuli are presented in quick succession, this study examines the neural mechanisms underlying potentiation of the visual evoked potential (VEP) in visual snow syndrome.

BACKGROUND:
Visual snow is a persistent visual disturbance characterized by rapid flickering dots throughout the visual field. Like the related condition of migraine with aura, visual snow has been hypothesized to arise from abnormal neuronal responsiveness, as demonstrated by a lack of typical VEP habituation to repeated visual stimulation. Yet the exact neural mechanisms underlying this effect remain unclear. Previous “double-pulse” experiments suggest that typical VEP habituation reflects disruptive gamma-band (50-70 Hz) neural oscillations, possibly driven by inhibitory interneurons. Given that migraine has been associated with reduced cortical inhibition, we propose here that visual snow may likewise reflect diminished inhibitory activity, resulting in decreased gamma power following initial visual stimulation and concomitant potentiation of the subsequent VEP response.

METHODS:
We compared VEP responses to double-pulse adaptation in a 22-year-old man with a 2-year history of visual snow versus a group of age- and gender-matched controls (N = 5). The patient does not have a comorbid diagnosis of episodic migraine or migraine with aura, and controls had no personal or family history of migraine.

RESULTS:
In contrast to the pattern of habituation observed in controls, visual snow was associated with persistent potentiation of the VEP response. Consistent with our predictions, time-frequency analysis revealed reduced gamma-band power following the initial stimulus in visual snow relative to controls.

CONCLUSIONS:
These results support an antagonistic interplay between gamma power and rapid neural adaptation, shedding new light on the neural mechanisms of VEP potentiation in visual snow.

© 2017 American Headache Society.

KEYWORDS:
P100 response; double-pulse adaptation; event-related potentials; time-frequency analysis

PMID: 29193050 DOI: 10.1111/head.13231

http://www.tinnitusjournal.com/articles/visual-snow-syndrome-and-its-relationship-to-tinnitus.html

https://www.ncbi.nlm.nih.gov/pubmed/28723606

Int Tinnitus J. 2017 Jun 1;21(1):74-75. doi: 10.5935/0946-5448.20170014.
Visual Snow Syndrome and Its Relationship to Tinnitus.
Renze M1.
Author information
Abstract
Visual snow is a symptom described as the continuous perception of tiny flickering dots in the entire field of vision, similar to static of an analog television. Visual snow syndrome is a cluster of symptoms found highly prevalent in patients that present with visual snow. While most of these symptoms appear to be visual in nature, approximately 63% of patients studied also report continuous bilateral tinnitus. The high correlation of visual-snow-syndrome patients presenting with tinnitus suggests that they may share a common underlying pathophysiology.

KEYWORDS:
tinnitus; visual snow; visual snow syndrome

PMID: 28723606 DOI: 10.5935/0946-5448.20170014

https://link.springer.com/article/10.1007%2Fs11940-017-0448-3

By initiating drug treatments with low doses and slowly increasing over 1 to 4 weeks, tolerability and compliance improves and allows patients to realize the full benefits of treatment. The proposed mechanisms of microstructural cortical abnormalities and hyperexcitability as a cause of VS may lead to new treatment approaches in the future. Until such a time, medications reported to relieve persistent visual phenomena of migraine and visual aura of migraine are treatment options worth considering and these are reviewed for that purpose. Although clinical trials for the treatment of visual snow are lacking due to the rarity of the disorder, medications reviewed here should be considered for use in patients with VS who experience an impact on their quality of life. Theoretical mechanisms that lead to cortical hyperexcitability are being investigated and could lead to new treatment options. In the meantime, medications may provide benefits in this disabling condition.

http://n.neurology.org/content/88/13/1243#sec-21

Behavioral measures of cortical hyperexcitability assessed in people who experience visual snow.

https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1004698

Optimal Information Representation and Criticality in an Adaptive Sensory Recurrent Neuronal Network
Oren Shriki ,Dovi Yellin
Published: February 16, 2016https://doi.org/10.1371/journal.pcbi.1004698

https://www.jocn-journal.com/article/S0967-5868(15)00653-0/fulltext

https://www.ncbi.nlm.nih.gov/pubmed/26791474

Visual snow: A thalamocortical dysrhythmia of the visual pathway?

https://link.springer.com/article/10.1007%2Fs11916-015-0497-9

Visual Snow—Persistent Positive Visual Phenomenon Distinct from Migraine Aura

https://www.ncbi.nlm.nih.gov/pubmed/25440184

https://www.sciencedirect.com/science/article/pii/S0181551214002678?via%3Dihub

[The visual snow phenomenon.]

J Fr Ophtalmol. 2014 Nov;37(9):722-727. doi: 10.1016/j.jfo.2014.08.001. Epub 2014 Oct 14.
[The visual snow phenomenon.] [Article in French] Zambrowski O1, Ingster-Moati I2, Vignal-Clermont C3, Robert MP4.
Author information
Abstract
INTRODUCTION:
Visual snow is a symptom described by some patients and poorly recognized by ophthalmologists. It consists in the permanent perception of a textured or a snowy vision, sometimes associated with palinopsia, exaggerated perception of the blue field entoptic phenomenon and photophobia. We report a group of patients suffering from visual snow in order to precise its characteristics and discuss its pathophysiology.

MATERIALS AND METHODS:
Prospective study of patients diagnosed between September 2010 and December 2012 with a visual snow phenomenon. For each patient, a formal ophthalmologic examination, an Amsler grid test, an automated visual field (central 20°), a color vision test (15 Hue), a full field, a pattern and a multifocal electroretinogram as well as flash and pattern visual evoked potentials (Métrovision©) were performed. A brain imaging was not systematically performed.

RESULTS:
Twelve patients aged 9-48old were included (six men and six women, 85 % of students). Several signs were variably associated with the visual snow phenomenon: palinopsia (50 %), constant blue field entoptic phenomenon (40 %), photophobia (30 %), migraine (30 %); in 20 % of cases, an initial toxic intake was found (20 %).

DISCUSSION:
This study highlights the reproducibility of typical symptoms described by patients reporting the visual snow phenomenon. This feature strongly supports the organic origin of the phenomenon. The pathophysiology of this phenomenon, however, remains unclear; the hypothesis of a lower threshold for perception of entoptic images cannot entirely account for the reported symptoms.

Copyright © 2014 Elsevier Masson SAS. All rights reserved.

KEYWORDS:
Entoptic phenomenon; Migraine; Neige visuelle; Palinopsia; Palinopsies; Photopsia; Photopsies; Phénomène entoptique du champ bleu; Snow vision

PMID: 25440184 DOI: 10.1016/j.jfo.2014.08.001

https://onlinelibrary.wiley.com/doi/full/10.1111/head.12378

The relation between migraine, typical migraine aura and “visual snow”.

https://academic.oup.com/brain/article/137/5/1419/334357

‘Visual snow’ – a disorder distinct from persistent migraine aura

https://jnnp.bmj.com/content/85/9/1057

https://www.ncbi.nlm.nih.gov/pubmed/24610941

Should ‘visual snow’ and persistence of after-images be recognised as a new visual syndrome?