Visual snow vs. migraine aura: Debate summary and novel insights into the syndrome

Visual snow syndrome (VSS) manifests as continuous, fine-grained visual static that is often accompanied by other visual symptoms. Its frequent association with migraine, particularly migraine with aura (MwA), has prompted debate regarding a shared pathogenic substrate. To interrogate this relationship, we performed a narrative review of clinical, neuroimaging and electrophysiological studies on VSS and MwA. The clinical picture of VSS is a persistent phenomenon that does not fluctuate with the migraine cycle and shows no response to therapeutics established to be useful in migraine. Moreover, structural and functional neuroimaging in VSS consistently demonstrates selective abnormalities within primary visual, salience and attentional networks, paralleled by distinctive evidence of glutamatergic dysregulation and impaired top-down suppression in electrophysiological recordings. Collectively, the available evidence supports VSS as a discrete disorder marked by aberrant salience assignment and impaired sensory gating, with clinical features and pathophysiology that are separate from those of MwA. While features such as shared serotonergic dysregulation, involvement of comparable cortical territories and high comorbidity suggest overlap between MwA and VSS, these similarities are likely better attributed to a shared predisposition for increased cortical excitability than to a single nosological entity. Future research aiming to characterize further network abnormalities in VSS will be pivotal for guiding the development of targeted therapies.