Clinical evaluation of visual snow syndrome: a structured narrative review with proposed clinical diagnostic approach

Visual snow syndrome (VSS) is a chronic neurological condition marked by persistent, bilateral, pan-field visual static and a constellation of additional visual and non-visual symptoms. Affecting an estimate of 2% of the populations, VSS remains substantially underdiagnosed, as its symptoms overlap with migraine aura and structural ophthalmological disease, and no standardised diagnostic protocol currently exists. This structured narrative review synthesises evidence on the clinical features, pathophysiology, comorbidities, and differential diagnosis. It also proposes a stepwise diagnostic approach for routine practice, distinguished from the advanced, research-oriented evaluations used to investigate underlying mechanisms. Converging neuroimaging and electrophysiological evidence suggests cortical hyperexcitability and large-scale network dysfunction may underlie VSS, though the precise mechanisms remain incompletely understood. We recommend a multidisciplinary, patient-centred management approach and identify biomarker development, multicentre validation of the diagnostic approach, and large-scale interventional trials as research priorities.