Visual snow: Not so benign.

Visual snow is the perception of flickering dots throughout the entire visual field and occurs with other symptoms of dysfunctional central sensory processing. We describe a patient who presented with visual snow, illusory visual motion, photopsia, and reduced night vision. He subsequently developed progressive cognitive impairment, myoclonus and ataxia. A diagnosis of sporadic Creutzfeldt-Jakob Disease was confirmed on post-mortem examination more than 49 months after symptom onset. The visual snow syndrome is typically benign, but our patient illustrates that occasionally it is the first manifestation of a serious brain disease. Careful application of the diagnostic criteria for the visual snow syndrome is important, particularly with the use of neuroimaging to exclude pathology in the occipital cortex.