Visual Snow Syndrome (VSS) is a condition where people constantly see flickering dots, like static on a TV screen, along with other visual disturbances. This study aimed to better understand the pathophysiology of Visual Snow (VS) using a combination of functional MRI (fMRI) and proton magnetic resonance spectroscopy.
Methods
Researchers compared 24 people with Visual Snow to 24 people without the condition, matched by age and gender. Participants underwent two types of brain scans. The first, functional MRI (fMRI), measured brain activity while they looked at patterns designed to mimic visual snow. The second, magnetic resonance spectroscopy (MRS), measured brain chemistry in a visual processing region called the right lingual gyrus.
Results
The brain scans showed clear differences between the two groups. People with Visual Snow had weaker brain activity in a region called the insula, which plays an important role in filtering and prioritizing sensory information. The brain chemistry tests revealed another difference: patients had higher levels of lactate in the right lingual gyrus compared to people without Visual Snow. Lactate is a substance linked to energy use and tends to build up when cells are under stress. Importantly, in patients with Visual Snow, higher lactate levels were directly linked to weaker brain responses during visual stimulation.
These findings suggest that Visual Snow Syndrome involves both changes in how the brain processes visual information and signs of metabolic stress in visual areas. The disrupted activity in the insula indicates that networks normally responsible for filtering sensory input may not function properly, while the elevated lactate levels suggest that the brain may be struggling with energy supply and demand in regions responsible for vision.
Together, these differences may explain why people with VSS experience persistent “visual static”—their brains may not have the capacity to filter and process visual information as efficiently as those without the condition.