Visual snow: Not so benign

Chen, Benson; Lance, Sean; Lallu, Bhavesh D; Anderson, Neil E.

doi:10.1016/j.jocn.2019.03.023

Cited by 26 publications

(20 citation statements)

References 5 publications

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“…It is known that topological visual disorders caused by hyper-function in V1/V2 areas can present with hallucinations similar to visual snow (90). Further, a recent case of sporadic Creutzfeldt-Jakob disease presenting with features of visual snow has been reported in the literature (91). These cases are, however, exceptional and they would certainly not explain most cases of VS in which no gross central nervous system abnormalities are found.…”

Section: Toward a Model For Visual Snowmentioning

confidence: 99%

Imaging the Visual Network in the Migraine Spectrum

et al. 2019

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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.

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Section: Toward a Model For Visual Snowmentioning

confidence: 99%

Imaging the Visual Network in the Migraine Spectrum

et al. 2019

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“… 4 5 While visual snow syndrome is typically benign, 4 it occasionally appears as the first symptom of serious neurological diseases such as the Heidenhain variant of Creutzfeldt-Jakob disease. 6 Beside neurological diseases, retinal diseases, persistent migraine aura, and hallucinogenic drugs must be excluded as possible causes of visual snow and palinopsia—visual snow syndrome must be diagnosed by exclusion after a thorough ophthalmic examination. 7 …”

Section: Introductionmentioning

confidence: 99%

Neuro-ophthalmologic Findings in Visual Snow Syndrome

et al. 2020

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Background and Purpose The findings of ophthalmic examinations have not been systematically investigated in visual snow syndrome. This study reviewed the abnormal neuroophthalmologic 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.

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“…Visual snow syndrome, by definition, is a benign condition and should not be associated with signs of a progressive ophthalmic or neurological disease. On rare occasions, however, visual snow symptoms have also been described in patients with serious neurological diseases such as Creutzfeldt-Jakob disease [9] or glycine receptor antibody syndrome [10]. The latter again seems to underpin a probable organic basis and emphasizes that careful adherence to diagnostic criteria, particularly the exclusion of other ophthalmic or neurologic disease, is essential.…”

Section: Introductionmentioning

confidence: 99%

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

Traber

Piccirelli

Michels

2020

Current Opinion in Neurology

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PURPOSE OF REVIEW Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant bilateral whole-visual field flickering or pixelation. When associated with additional visual symptoms, it is referred to as visual snow syndrome. Its pathophysiology remains elusive. This review highlights the visual snow literature focusing on recent clinical studies that add to our understanding of its clinical picture, pathophysiology, and treatment. RECENT FINDINGS Clinical characterization of visual snow syndrome is evolving, including a suggested modification of diagnostic criteria. Regarding pathophysiology, two recent studies tested the hypothesis of dysfunctional visual processing and occipital cortex hyperexcitability using electrophysiology. Likewise, advanced functional imaging shows promise to allow further insights into disease mechanisms. A retrospective study now provides Class IV evidence for a possible benefit of lamotrigine in a minority of patients. SUMMARY Scientific understanding of visual snow syndrome is growing. Major challenges remain the subjective nature of the disease, its overlap with migraine, and the lack of quantifiable outcome measures, which are necessary for clinical trials. In that context, refined perceptual assessment, objective electrophysiological parameters, as well as advanced functional brain imaging studies, are promising tools in the pipeline.

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Visual snow: Not so benign

Cited by 26 publications

References 5 publications

Imaging the Visual Network in the Migraine Spectrum

Imaging the Visual Network in the Migraine Spectrum

Neuro-ophthalmologic Findings in Visual Snow Syndrome

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

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