Can We Speak of Lack of Habituation in Visual Snow?

Fantini, Jacopo; Sartori, Arianna; Manganotti, Paolo

doi:10.1111/head.12957

Cited by 6 publications

(8 citation statements)

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“…Because all SOA conditions were randomly interleaved, rather than presented in successive blocks, the observed difference is unlikely to be explained by confounding factors such as fluctuations in attention or increasing fatigue. 7,8 More significantly, our data provide a novel mechanistic link between VEP potentiation and neural oscillations in the gamma band. In line with previous research, 13 we observed an antagonistic relationship between pre-S2 gamma power and the subsequent evoked response, with reduced gamma synchronization in visual snow.…”

Section: Discussionmentioning

confidence: 72%

“…This potentiation effect was visible across a range of tested SOAs, and persisted beyond the recovery from adaptation observed in control participants. Because all SOA conditions were randomly interleaved, rather than presented in successive blocks, the observed difference is unlikely to be explained by confounding factors such as fluctuations in attention or increasing fatigue …”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this idea, a recent study reported VEP potentiation associated with visual snow . However, these results have been questioned due to the patient's prior history of migraine with aura, as well as more general concerns about the reliability of VEP habituation in migraine …”

mentioning

confidence: 96%

“…5 Consistent with this idea, a recent study reported VEP potentiation associated with visual snow. 6 However, these results have been questioned due to the patient's prior history of migraine with aura, 7 as well as more general concerns about the reliability of VEP habituation in migraine. 8 Here, we tested VEP habituation in a 22-yearold male visual snow patient without comorbid migraine, ruling out underlying migraine with aura as a confounding factor.…”

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confidence: 99%

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Antagonistic Relationship Between VEP Potentiation and Gamma Power in Visual Snow Syndrome

2017

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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 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.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

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confidence: 96%

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confidence: 99%

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Antagonistic Relationship Between VEP Potentiation and Gamma Power in Visual Snow Syndrome

2017

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“…In our previous case report, we have demonstrated that loss of habituation ability in a VS patient with migraine was improved with lamotrigine treatment . There was a comment whether loss of habituation was due to visual snow or migraine to our case report . Our preliminary study promoted us to further characterize the clinical and neurophysiological characteristics of VS patients with or without migraine.…”

Section: Introductionmentioning

confidence: 99%

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

2019

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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.

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

Eren

Rauschel

Ruscheweyh

et al. 2018

Annals of Neurology

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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

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Can We Speak of Lack of Habituation in Visual Snow?

Cited by 6 publications

References 8 publications

Antagonistic Relationship Between VEP Potentiation and Gamma Power in Visual Snow Syndrome

Antagonistic Relationship Between VEP Potentiation and Gamma Power in Visual Snow Syndrome

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

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

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