Visual contrast perception in visual snow syndrome reveals abnormal neural gain but not neural noise

Brooks, Cassandra J.; Chan, Yu Man; Fielding, Joanne; White, Owen; Badcock, David R.; McKendrick, Allison M

doi:10.1093/brain/awab383

Cited by 11 publications

(18 citation statements)

References 59 publications

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“…These results were confirmed by the same group when comparing visual contrast perception in patients with VSS with and without migraine, healthy controls and migraineurs, finding what can be described as increased neural responses to external stimuli in VSS [57].…”

Section: Neuro-ophthalmologysupporting

confidence: 67%

Visual snow syndrome and migraine: a review

Silva

Puledda

2023

Eye

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Visual snow syndrome is a neurological condition characterized by ongoing prominent phenomena described consistently as tiny dots moving across the entire visual field, often associated with complex visual symptoms. These can take the form of afterimages, entoptic phenomena, nyctalopia and light sensitivity. Although some of these symptoms can be benign, they can nonetheless become significantly impactful for many who experience them, particularly in cases that have a sudden and abrupt start. As visual snow syndrome becomes increasingly recognized in clinical practice we begin to learn about its typical presentation and underlying pathophysiology. Treatment of visual snow, however, still proves quite challenging, and efforts need to be focused on unravelling the biological mechanisms of the syndrome. This endeavour has characterized the most recent research on visual snow, mostly involving neuroimaging, neurophysiological and neurobehavioral studies aimed at understanding its underlying neural signature. Another important aspect of the syndrome, which will likely prove critical in deepening our understanding of visual snow, is represented by the intricate biological and historical connexion with migraine. This narrative review focused on visual snow syndrome will explore its clinical, pathophysiological and treatment aspects in detail.

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Section: Neuro-ophthalmologysupporting

confidence: 67%

Visual snow syndrome and migraine: a review

Silva

Puledda

2023

Eye

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“…The underlying mechanism for lingual hypermetabolism at rest can be a combination of hyperexcitation due to neural hypersensitivity [ 17 ] and underlying grey matter increases [ 13 , 22 ]. As grey matter increases in the lingual gyrus were only modest in this patient group (only after small volume correction in VBM), our finding indicates that functional hyperexcitability may be a more dominant driver of the observed increase in metabolic activity.…”

Section: Discussionmentioning

confidence: 99%

“…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. Cortical hyperexcitability, due to increased neural contrast gain rather than abnormal neural noise [ 17 ], changes in specific visual streams, altered thalamocortical pathways and dysfunction of higher-level salience network controls have been suggested [ 18 ]. Interestingly, tinnitus, considered the auditory analogue to visual snow, is also highly prevalent in VSS, which suggests a common pathway [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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Purpose Visual snow syndrome (VSS) is a recently recognized chronic neurologic condition characterized by the constant perceiving of tiny flickering dots throughout the entire visual field. Metabolic overactivity and grey matter volume increase in the lingual gyrus has been reported. We investigated this by 18F-FDG PET/MR in comparison to healthy controls. Aside from voxel-based characterization, the classification accuracy of volume-of-interest (VOI)-based multimodal assessment was evaluated, also in comparison with visual analysis. Methods Simultaneous 18F-FDG PET and MR imaging was performed in 7 patients with VSS (24.6 ± 5.7 years; 5 M/2F) and 15 age-matched healthy controls (CON) (28.0 ± 5.3 years; 8 M/7F). SPM12 and voxel-based morphometric analysis was performed. A VOI-based discriminant analysis was performed with relative 18F-FDG uptake, MR grey matter (GM) volumes and their combination. A visual analysis was done by two blinded experienced readers. Results Relative increased hypermetabolism was found in VSS patients in the lingual gyrus and cuneus (pFWE < 0.05, peak change + 24%), and hypometabolism in the mesiotemporal cortex (pheight,uncorr < 0.001, peak change − 14%). VSS patients also had increased GM volume in the limbic system and frontotemporal cortex bilaterally (pFWE < 0.05), and in the left secondary and associative visual cortex and in the left lingual gyrus (pheight,uncorr < 0.001). Discriminant analysis resulted in 100% correct classification accuracy for 18F-FDG with lingual gyrus, cuneus and lateral occipital lobe (BA 17 and BA 18) as main discriminators. Unimodal MR- and combined 18F-FDG + MR classification resulted in an accuracy of 91% and 95%, respectively. Visual analysis of 18F-FDG was highly observer dependent. Conclusion Patients with VSS have highly significant structural and metabolic abnormalities in the visual and limbic system. VOI-based discriminant analysis of 18F-FDG PET allows reliable individual classification versus controls, whereas visual analysis of experienced observers was highly variable. Further investigation in larger series, also in comparison to VSS mimicking disorders such as migraine, is warranted. Trail registration: Retrospectively registered at clinicaltrials.gov under NCT05569733 on Oct 5, 2022.

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“…The underlying mechanism for lingual hypermetabolism at rest can be a combination of hyperexcitation due to neural hypersensitivity [17] and underlying grey matter increases [13,22]. As grey matter increases in the lingual gyrus were only modest in this patient group (only after small volume correction in VBM), our nding indicate that functional hyperexcitability may be a more dominant driver of the observed increase in metabolic activity.…”

Section: Discussionmentioning

confidence: 63%

“…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. Cortical hyperexcitability, due to increased neural contrast gain rather than abnormal neural noise [17], changes in speci c visual streams, altered thalamocortical pathways and dysfunction of higher-level salience network controls have been suggested [18]. Interestingly, tinnitus, considered the auditory analogue to visual snow, is also highly prevalent in VSS, which suggests a common pathway [19].…”

Section: Introductionmentioning

confidence: 99%

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

Laere

Ceccarini

Gebruers

et al. 2022

Preprint

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Purpose Visual snow syndrome (VSS) is a recently recognized chronic neurologic condition characterized by the constant perceiving of tiny flickering dots throughout the entire visual field. Metabolic overactivity and grey matter volume increase in the lingual gyrus has been reported. We investigated this by 18F-FDG PET/MR in comparison to healthy controls. Aside from voxel-based characterization, the classification accuracy of volume-of-interest (VOI) based multimodal assessment was evaluated, also in comparison with visual analysis. Methods Simultaneous 18F-FDG PET and MR imaging was performed in 7 patients with VSS (24.6 ± 5.7 yrs; 5M/2F) and 15 age-matched healthy controls (CON) (28.0 ± 5.3 yrs; 8M/7F). SPM12 and voxel-based morphometric (VBM) analysis was performed. A VOI-based discriminant analysis was performed with relative 18F-FDG uptake, MR grey matter (GM) volumes and their combination. A visual analysis was done by two blinded experienced readers. Results Relative increased hypermetabolism was found in VSS patients in the lingual gyrus and cuneus (pFWE<0.05, peak change + 24%), and hypometabolism in the mesiotemporal cortex (pheight,uncorr<0.001, peak change − 14%). VSS patients also had increased GM volume in the limbic system and frontotemporal cortex bilaterally (pFWE<0.05), and in the left secondary and associative visual cortex and in the left lingual gyrus (pheight,uncorr <0.001). Discriminant analysis resulted in 100% correct classification accuracy for 18F-FDG with lingual gyrus, cuneus and lateral occipital lobe (BA 17 and BA 18) as main discriminators. Unimodal MR- and combined 18F-FDG + MR classification resulted in an accuracy of 91% and 95%, respectively. Visual analysis of 18F-FDG was highly observer dependent. Conclusion Patients with VSS have highly significant structural and metabolic abnormalities in the visual and limbic system. VOI-based discriminant analysis of 18F-FDG PET allows reliable individual classification versus controls, whereas visual analysis of experienced observers was highly variable. Further investigation in larger series, also in comparison to VSS mimicking disorders such as migraine, is warranted. Retrospectively registered at clinicaltrials.gov under NCT05569733 on Oct 5, 2022.

show abstract

Visual contrast perception in visual snow syndrome reveals abnormal neural gain but not neural noise

Cited by 11 publications

References 59 publications

Visual snow syndrome and migraine: a review

Visual snow syndrome and migraine: a review

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

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

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