‘Visual snow’ – a disorder distinct from persistent migraine aura

Abstract

Patients with 'visual snow' report continuous tiny dots in the entire visual field similar to the noise of an analogue television. As they frequently have migraine as a comorbidity with ophthalmological, neurological and radiological studies being normal, they are offered various diagnoses, including persistent migraine aura, post-hallucinogen flashback, or psychogenic disorder. Our aim was to study patients with 'visual snow' to characterize the phenotype. A three-step approach was followed: (i) a chart review of patients referred to us identified 22 patients with 'visual snow'. Fifteen had additional visual symptoms, and 20 patients had comorbid migraine, five with aura; (ii) to identify systematically additional visual symptoms, an internet survey (n = 275) of self-assessed 'visual snow' subjects done by Eye On Vision Foundation was analysed. In two random samples from 235 complete data sets, the same eight additional visual symptoms were present in >33% of patients: palinopsia (trailing and afterimages), entoptic phenomena (floaters, blue field entoptic phenomenon, spontaneous photopsia, self-light of the eye), photophobia, and nyctalopia (impaired night vision); and (iii) a prospective semi-structured telephone interview in a further 142 patients identified 78 (41 female) with confirmed 'visual snow' and normal ophthalmological exams. Of these, 72 had at least three of the additional visual symptoms from step (ii). One-quarter of patients had 'visual snow' as long as they could remember, whereas for the others the mean age of onset was 21 ± 9 years. Thirty-two patients had constant visual symptoms, whereas the remainder experienced either progressive or stepwise worsening. Headache was the most frequent symptom associated with the beginning or a worsening of the visual disturbance (36%), whereas migraine aura (seven patients) and consumption of illicit drugs (five, no hallucinogens) were rare. Migraine (59%), migraine with aura (27%), anxiety and depression were common comorbidities over time. Eight patients had first degree relatives with visual snow. Clinical investigations were not contributory. Only a few treatment trials have been successful in individual patients. Our data suggest that 'visual snow' is a unique visual disturbance clinically distinct from migraine aura that can be disabling for patients. Migraine is a common concomitant although standard migraine treatments are often unhelpful. 'Visual snow' should be considered a distinct disorder and systematic studies of its clinical features, biology and treatment responses need to be commenced to begin to understand what has been an almost completely ignored problem.

Visual Snow Syndrome and Its Relationship to Tinnitus

“…Visual Snow Syndrome is a cluster of symptoms found highly prevalent in patients that present with visual snow 2 . While most of these symptoms appear to be visual in nature, 62-64% of patients studied also report continuous bilateral tinnitus [1][2][3] .…”

“…Visual Snow is a symptom described as the continuous perception of tiny flickering dots in the entire field of vision, similar to static of an analog television 1 . Visual Snow Syndrome is a cluster of symptoms found highly prevalent in patients that present with visual snow 2 .…”

“…In 2014, Schankin et al 1 attempted to characterize the disorder using a chart review of 22 patients with visual snow, an internet survey of 275 self-assessed visualsnow subjects, and a phone interview with an additional 142 patients. This study demonstrated that visual snow syndrome was a unique disorder distinct from migraine and typical migraine with aura.…”

“…There is currently no known treatment for visual snow syndrome 1,3 . In addition, because visual snow syndrome is largely unknown in the medical community, patients are often misdiagnosed as having migraine with aura, hallucinogen persisting perception disorder (HPPD), psychogenic disorders or malingering 2,3 .…”

The frequency of the 'visual snow' phenomenon in patients with migraine

“…Objekat može da ostavlja i "trag" za sobom (1). Palinopsija se dovodi u vezu sa mnogim stanjima, uključujući upotrebu halucinogena kao što je LSD (13), fokalne neurološke lezije (14,15) i migrenu (15).…”