Visual Snow is a poorly understood condition. Our group led by Dr Schankin and Professor Goadsby at The University of California, San Francisco have been investigating visual snow for the last few years1. In our experience the constant flickering dots in the entire visual field (TV static – the main symptom) is the most common symptom defining the syndrome and is almost always associated with additional visual symptoms. The additional symptoms include various combinations of the following – blue entoptic phenomenon (pronounced symptoms of seeing ‘wiggly lines’ or ‘darts’ looking at blue sky), after-images, trailing of after-images, increased sensitivity to bright light, poor vision in dim light, pronounced floaters, self-light of eye (‘whorls’ of light on closing eyes) and ringing in ears. We have found remarkable consistency in symptoms in a prospective study compared to a retrospective analysis of a different group
Many patients are anxious about their symptoms, understandably. Most patients have migraine and many have typical migraine aura (zig-zag lines or dark spots changing in size or location lasting for 5-60 minutes).
The majority of patients have normal imaging and normal ophthalmological tests.
So, what causes Visual Snow?
The cause of this condition is unknown. Our group used special scans called FDG-PET which looks at the function of the brain2. Comparing visual snow patients with controls, we found increased metabolism (function) in a part of the brain (called occipital area – at the back of the brain). This area is called the lingual gyrus which is one of the additional areas (supplementing the main visual area) that interprets vision. Therefore it is possible that these symptoms are associated with increased activity of stimulating areas or decreased activity in the inhibitory areas along the visual pathway or areas modulating the pathway.
As far as treatment is concerned there are no proven options.
1 ‘Visual snow’ – a disorder distinct from persistent migraine aura. Schankin CJ, Maniyar FH, Digre KB, Goadsby PJ. Brain. 2014 May;137(Pt 5):1419-28.
2. The relation between migraine, typical migraine aura and “visual snow”. Schankin CJ, Maniyar FH, Sprenger T, Chou DE, Eller M, Goadsby PJ. Headache. 2014 Jun;54(6):957-66
You are the first doctor I have met who has given me a logical explanation for visual snow
CR, patient with Visual snow
To make an appointment for a private consultation with Dr Maniyar, Please call at the following numbers depending on your desired hospital –
1. City of London Medical Center, Tower Hill (London Bridge Hospital branch) – +44(0)20 7234 2009
2. The London Independent Hospital (BMI), Stepney Green, London – 020 7780 2400
3. The Nuffield Brentwood Hospital, Essex – 01277 695695 ‘
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