This multimodal imaging study found VS to be associated with regional structural and functional alterations in the early and higher visual cortex, as well as with hyperconnectivity to the temporal cortex. The involved brain regions are related to visual processing, memory, spatial attention, and cognitive control. Both functional and structural changes arise in VS patients, be it as an epiphenomenon or as a direct contributor to the pathomechanism of VS. The tight link of GMV in both lingual gyri to symptom duration underlines the critical role of the lingual gyrus in disease manifestation. These in vivo neuroimaging biomarkers may hold potential as objective measures of this intriguing condition, which cannot yet be objectively quantified.
Our results show that visual snow symptoms are exacerbated by colour modulation that selectively increased levels of S-cone excitation. Because S-cone signals travel on primordial brain pathways that regulate cortical rhythms (koniocellular pathways) we hypothesis that these pathways contribute to the pathogenesis of this disorder.
In summary, modern neuroimaging has allowed to detect several functional, structural and metabolic changes affecting multiple elements of the visual network in migraineurs, both with and without aura. These abnormalities help explain some of the key features of the condition, such as abnormal sensory processing, photophobia and the aura phenomenon, and further link it to the growingly recognized neurological syndrome of visual snow. In this condition, which is likely on a similar pathophysiological spectrum as migraine, multiple elements (i.e., cortical hypermetabolism, thalamo-cortical dysrhythmia, brain network dysfunctions) could be at play in the generation of a persistent visual illusion.
This study demonstrates that magnetic suppression of perceptual accuracy, in contrast to the situation in migraine with aura, is not reduced in VSS compared to migraine-matched controls. Therefore, although hyperexcitability apparently occurs in both VSS and migraine aura, the locations seem to be different. The primary visual cortex might not be the main location in VSS.
This study aims to investigate the feasibility of the use of repetitive transcranial magnetic stimulation (rTMS) for symptoms associated with Visual Snow syndrome (VS).