Visual Snow: What is this neurological disorder all about?
Visual Snow Introduction
Visual snow is a poorly understood neurological disorder that is just recently being studied as an entity of its own. People often describe it as a like a TV set without reception... that black and white static overlying across the visual field. A static that can be thin or thick, rapid moving or slow. It makes the world a little grainy and indistinct but shifting and moving at the same time. It is not unknown for people to describe heatwave effects, pulsing in the air, flickering in the visual field or other distortions within this static. Visual Snow is a visual condition often connected with persistent migraine auras but it can be seen it people who do not have migraines and in people who have migraines but experience no other aura phenomena. In fact, it does not behave like a migraine aura at all. Rather it seems like the visual filter hyperactive and not filtering out all that visual noise as it were so the individual perceives this constant moving static in their visual field. It is commonly worse in dim and dark environments but can be perceived at all times. This continuous visual disturbance consists of white and black dots, although some do have colours, in the entire visual field. A “female-to-male ratio of 1:2.2 was reported and 92% of patients had no response to medication. It appears to be a unique disease entity presenting clinically distinct from visual aura, and is often associated with other visual symptoms including floaters, palinopsia, halos, photophobia, and phosphenes. However, its onset seems to coincide with headache onset, and has a high prevalence among patients who have migraine without and with visual aura. The etiology is unknown.” (Primary headache disorders and neuroophthalmologic manifestations” Dove Press Journal Sept 13, 2012)
Most neurologists believe the condition is a migrainous phenomena in some way which is why most people with visual snow are diagnosed with persistent migraine aura. Yet visual snow does not act like a migraine aura nor does it typically respond to regular migraine preventative treatments. In fact recently it has been stated by Dr. Christoph Schankin “Visual snow is almost always associated with additional visual symptoms. It therefore represents a unique clinical syndrome – the visual snow syndrome," he said at the annual meeting of the American Headache Society. "It is distinct from visual aura in migraine; migraine with and without aura are common comorbidities, but we don’t actually know at the moment what is the pathological link between those two conditions.”
One of the unfortunate stigmas associated with visual snow is that it is caused by illicit drug use however according to research only a small percentage of people with the syndrome have ever used drugs. At the annual meeting of the American Headache Society Dr. Christoph Schankin said to Frontline news “the intake of illicit drugs is not relevant.”
The prevalence of other visual phenomena that occurs with visual snow is “floaters (73%); persistent visual images (63%); difficulty seeing at night (58%); tiny objects moving on the blue sky (57%); sensitivity to light (54%); trails behind moving objects (48%); bright flashes (44%); and coloured swirls, clouds, or waves when their eyes were closed (41%)” Some of which clearly relate to photophobia, imparied night vision and palinopsia which is trailing and prolonged after images, all of which are phenomena one does see in persistent migraine auras as well in some patients. However some of the symptoms clearly fall into the category of entoptic phenomena related directly to the eyes such as “floaters (likely protein aggregations in the vitreous fluid that cast a shadow on photoreceptors); photopsia (bright flashes typically elicited by mechanical stimulation of the eyes); Scheerer’s phenomenon (small moving objects against the sky thought to be due to blood cells moving in the retinal vessels that cast a shadow on the photoreceptors); and self-light of the eye (the colored swirls, clouds, and waves), whose etiology is unknown.” (Visual snow may be a distinct clinical entity)
The visual snow is not perceived the same way by every individual and in fact can vary dramatically. During a telephone portion of the study conducted by Dr. Christoph Schankin involving 120 people with visual snow results showed “that the textural patterns described for the snow varied considerably. The most common pattern reported was dots alternating from black (on light backgrounds) to white (on dark backgrounds) (48%), while some patients reported flashing dots, transparent dots, or other patterns. "We don’t know what that means – whether that has some pathophysiologic relevance," Dr. Schankin commented.” In addition “Analysis restricted to the subset reporting black and white dots showed that 98% had at least one additional visual symptom, and 93% had three or more. In this part of the study, another symptom identified was halos or starbursts, seen in 65% of cases.”(Visual snow may be a distinct clinical entity)
It is interesting to note as well that “Of the 40 patients with onset of visual snow later in life, 54% had a history of migraine. However, when asked about events in the week before the onset of visual snow, only 33% reported headache, and just 10% reported aura symptoms. But none had classic features of visual aura, such as unilaterality, zig-zag lines, or scotoma, during visual snow. Additionally, only 8% had used illicit drugs, mainly marijuana, in the week leading up to the start of visual snow, and none had significant ophthalmologic findings.”(Visual snow may be a distinct clinical entity) Indeed, while visual snow is found commonly among people with migraines the fact it occurs without migraines at all is fascinating in itself for research. Likewise, when it occurs in migraine patients without aura that is a clear indication something else is going on neurologically. It would be interesting to have a study to compare people with just visual snow and people with visual snow with migraines without aura. Migraines have a peculiar way of firing up the brain even when the migraine is not present, as in such studies that show photophobia when a migraine is not present. It would be interesting to see if there is something about having migraines, of a certain frequency or duration of having them, that makes the brain more susceptible to developing visual snow. In this case, ignoring the visual aura phenomena that might happen to be affecting the same area of the brain in patients with migraine with aura. Or maybe comparing all three. Another interesting factor research much consider are the other symptoms. Those of halos and starbursts and things one might see with people with migraines occurring... is this a hyperactivity issue or similar to a migraine aura occurring in a similar fashion? Symptoms associated with the eyes themselves are even more puzzling but if the brain isn't filtering information properly it could have a connection to increased perception of visual phenomenon that is normal but just more frequent. Either way something is making the system go haywire and by comparing those with just the visual snow to those with migraines and visual snow it might help see what the factors are that cause this to happen. New studies on just visual snow, however show promise in revealing more insight in what is going on with this neurological disease.
It is a fascinating problem it presents trying to sort out what is causing it, what is going on and what treatments would actually be effective. For the people suffering it they often receive little care, more indifference from neurologists than anything or a lot of treatments that do a lot of nothing. It can cause a great deal of frustration, confusion, and anxiety because the condition is a constant distorting perceptual phenomenon that can affect a great deal of a person's life.
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Visual Snow image
Old migraine case studies: Descriptions and treatments
These case studies come from persistent migraine aura research which up to present has been the majority of the case studies we have seen for treatment. Now that VS is being studies on its own, with another study due to come out Spring 2014, we should know more above the syndrome as well as potential treatments for it. Old treatments as we can see from these case studies follow along with migraine treatments to treat persistent migraine auras but is vastly less successful at treating the VS.
Nevertheless you might find them interesting to read as you will recognize the patients symptoms as VS. And you will see what their neurologists went about to treat it as well as whether the treatment was successful or not.
“Three-and-a-half years prior to evaluation, the patient developed a constant “rain-like” pattern in front of both eyes, at times appearing like a carpet background, often associated with the illusion of motion. Despite atenolol, the visual patterns intensified and converted to persistent “heat waves” with flickering lights. Although extremely uncomfortable, they did not interfere with visual function. She also reported five episodes of visual “black-out” and bright “daggers and spots” lasting 40 seconds each. He complained of 8 months of “snow” and “flickering” similar to what was “between TV channels.” Initially experienced only in dark illumination, eventually the visual phenomena became constant, without headaches. SPECT scan revealed bilateral parieto-occipital hypoperfusion. An EEG was not performed. Nifedipine was unhelpful, but sertraline reduced the visual phenomena by 50%.” (The last couple of sentences there apply to migraine auras and not VS just to be clear about that. This is a good example of someone with PMA characteristics and VS symptoms).
“she saw constant white and black dots, “snow,” and “TV static” over her entire visual field that worsened when she stared at a white background. Later, persistence of visual images (palinopsia) developed.”
“They commonly described diffuse small particles, such as TV static, snow, lines of ants, dots, and rain, that lasted for months to years. Some patients reported greater awareness of the visual phenomena when looking at the sky or at a light-colored wall. Complex phenomena such as palinopsia, micropsia, and formed hallucinations were exceptional. Some characterized these unformed visual hallucinations as bothersome, uncomfortable, or emotionally disabling, but not as interfering with visual function. Other patients were unconcerned by them. For the most part, medications such as tricyclic agents, calcium channel andbeta blockers, and analgesics were unhelpful. The patients’ ages varied from 9 to 67 years;”
Persistent positive visualphenomena in migraineG.T. Liu, MD; N.J. Schatz, MD; S.L. Galetta, MD; N.J. Volpe, F. Skobieranda, MD; and G.S. Kosmorsky, DO666 NEURO1,OGY 45 April 1995
“Over the next few years, the visual phenomenon was described as “snowy vision,” which was, present all the time and would worsen episodically, unassociated with pain. The subject described the visual phenomenon as like looking at a television with bad reception. It moved and swirled, and covered his entire visual field. When he looked at the sky or a white wall, the snowy effect was dark gray. He also saw constant “sparks,”“shooting stars,” and “floaters.”
When the patient closed his eyes or looked at a dark surface, he saw the same effects, except that all of the visual phenomena were white, similar to looking at a sky full of moving and shooting stars.”495
“Since the age of 7, she rather constantly sees what she describes as television static that is getting worse and more noticeable. She sees tiny air molecules, also described as rain on a window, which are most noticeable if she is looking at the sky or a white background, present in both eyes and with the eyes closed. The symptoms can interfere with reading. “494
PMA”Medications reported as effective cyproheptadine, dihydroergotamine, divalproex sodium, (mono- and polytherapy) furosemide intravenous 20 mg once and verapamil, fusosemide intravenous 20 mg once, lamotrigine polytherapy, and nimodipine. In Dr. experience, low doses of divalproex sodium, and topiramate have been effective. In persistent visual aura was less intense on topiramate mg daily, and the palinopsia resolved. from starting treatment and complete response from several hours to 2 months and was typically weeks. Of the cases reviewed by Wang et reported headache improvement after treatment. the headache improved despite persistent symptoms, and in 2, the headache improved complete resolution of the visual symptoms. Most patients were reported as unresponsive numerous medications including aspirin, naproxen, carbamazepine, phenytoin, phenobarbital, divalproex sodium, lamotrigine, topiramate, diazepam, flunarizine, nimodipine, citicoline, verapamil, fluoxetine, sertraline, amitriptyline, nortriptyline, dothiepin, nifedipine, baclofen, propranolol, metoprolol, atenolol, sumatriptan, methylprednisolone,magnesium, acetazolamide, and pizotifen.
Migraine With Persistent Visual AuraHeadache 2012 American Headache Society (Headache 2012;52:494-501)
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Links to simulators
Visual snow in the News
- WNYT.com - Visual Snow: it's like having a sort of TV static in your field of vision all the
- Chloe Brookes: The woman who sees snowflakes even when it's sunny | Mail Online
The snow may be over for most of us, but for Chloe Brookes it’s a year-round nightmare. She suffers from a type of migraine doctors are still learning about.
- 'Visual Snow' Called Real, Not Drug Related
NEW ORLEANS -- A mysterious and troubling phenomenon called visual snow is a distinct syndrome that does not appear to stem from illicit drug use, nor is it a migraine aura, a researcher said here.
- Visual Snow
Eye On Vision Foundation - Floaters, Visual Snow, Macular Degeneration
- Visual Snow: Share your experiences. HELP RAISE AWARENESS. - Home
Site to promote visual snow awareness
- Visual Snow Group
Visual snow group for people with visual snow. Have a great resource of information and support.
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