Previous studies of Visual snow syndrome (VSS) have shown abnormalities in brain regions involved in visual perception and sensory integration. This study aimed to better understand how these regions communicate with each other when the brain is at rest, and whether these communication patterns are related to VSS symptoms and visual processing measured through eye movements.
Researchers scanned 40 people with VSS and 60 individuals without VSS using ultra-high-resolution 7-Tesla MRI. They measured resting-state functional connectivity, which reflects how strongly different brain regions’ activity is synchronized when no task is being performed. Brain connectivity patterns were compared between groups and related to symptom severity, perceived disruptiveness, and eye-movement reaction times.
Compared with healthy controls, individuals with VSS showed stronger connectivity between the supramarginal gyrus (a region involved in sensory integration) and visual cortical areas. They also showed weaker connectivity between this region and deeper brain structures, as well as reduced connectivity between the parahippocampal gyrus and visual cortex. Some of these weaker connections were associated with patients reporting their symptoms as more disruptive. No differences were found between VSS patients with and without migraine.
Overall, the findings indicate that VSS is associated with altered communication within visual and sensory brain networks, characterized by increased connectivity between certain cortical visual areas and reduced connections with deep grey matter and temporal regions. These network changes may help explain the persistent and disruptive nature of visual symptoms in VSS.