Department of Neurology, LMU Munich, University Hospital-Großhadern, Munich, Germany.
Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Prog Brain Res. 2020;255:311-326. doi: 10.1016/bs.pbr.2020.05.020. Epub 2020 Jun 15.
Visual snow syndrome is a debilitating disorder characterized by tiny flickering dots (like TV static) in the entire visual field and a set of accompanying visual (palinopsia, enhanced entoptic phenomena, photophobia, nyctalopia), nonvisual (e.g. tinnitus) and nonperceptional (e.g. concentration problems, irritability) symptoms. Its pathophysiology is enigmatic and therapy is often frustrating.
To summarize our current understanding of pathophysiology and treatment of visual snow syndrome.
A systematic search of PubMed database was performed using the key word "visual snow" and predefined in- and exclusion criteria. The results were stratified into "treatment" and "pathophysiology." Additionally, we conducted a search with the key words "persistent migraine aura" and "persistent visual aura" and screened for mis-diagnosed patients actually fulfilling the criteria for visual snow syndrome. The reference lists of most publications and any other relevant articles known to the authors were also reviewed and added if applicable.
From the 50 original papers found by searching for "visual snow," 21 were included according to the inclusion and exclusion criteria. Additional four publications came searching for "persistent migraine aura" or "persistent visual aura." Further publications derived from literature references resulting in a total of 20 articles for pathophysiology and 15 for treatment with some overlaps. Regarding pathophysiology, hyperexcitability of the visual cortex and a processing problem of higher order visual function are assumed, but the location is still in discussion. In particular, it is unclear if the primary visual cortex, the visual association cortex or the thalamocortical pathway is involved. Regarding treatment, data is available on a total of 153 VSS patients with medication mentioned for 54 resulting in a total of 136 trials. From the 44 different medications tried, only eight were effective at least once. The best data is available for lamotrigine being effective in 8/36 (22.2%, including one total response and no worsening), followed by topiramate being effective in 2/13 (15.4%, no total response and one worsening). The only other medication resulting in worsening of VSS was amitriptyline according to our literature review. The others reported to be effective at least once were valproate, propranolol, verapamil, baclofen, naproxen and sertraline. The nonpharmacological approach using color filters of the yellow-blue color spectrum might also be helpful in some patients.
Visual snow syndrome is still far from being fully understood. In respect of pathophysiology, a disorder of visual processing is likely. The best pharmacological evidence exists for lamotrigine, which can be discussed off-label. As nonpharmacological option, patients might benefit from tinted glasses for everyday use.
视觉雪综合征是一种使人衰弱的疾病，其特征是整个视野中出现微小闪烁的点（如电视静电）和一系列伴随的视觉（后像、增强的内视现象、畏光、夜盲）、非视觉（如耳鸣）和非感知症状（如注意力问题、易怒）。其病理生理学仍然是一个谜，治疗往往令人沮丧。
总结我们目前对视觉雪综合征的病理生理学和治疗的理解。
通过使用关键词“视觉雪”和预定义的纳入和排除标准，对 PubMed 数据库进行系统搜索。结果分为“治疗”和“病理生理学”。此外，我们还使用关键词“持续性偏头痛先兆”和“持续性视觉先兆”进行了搜索，并筛选出误诊为实际上符合视觉雪综合征标准的患者。还查阅了大多数出版物的参考文献列表和作者已知的任何其他相关文章，并在适用时添加。
通过搜索“视觉雪”，从 50 篇原始论文中找到了 21 篇符合纳入和排除标准的论文。另外有 4 篇论文是通过搜索“持续性偏头痛先兆”或“持续性视觉先兆”找到的。进一步的出版物来源于文献参考文献，共产生了 20 篇关于病理生理学的文章和 15 篇关于治疗的文章，其中有一些重叠。关于病理生理学，假设视觉皮层的过度兴奋和高级视觉功能的处理问题，但位置仍在讨论中。特别是，尚不清楚初级视觉皮层、视觉联合皮层还是丘脑皮质通路是否参与其中。关于治疗，共有 153 名 VSS 患者的药物治疗数据被提及，其中 54 名患者进行了治疗，共进行了 136 次试验。在尝试的 44 种不同药物中，只有 8 种至少有一次有效。关于拉莫三嗪的疗效数据最好，8/36（22.2%，包括 1 例完全缓解和 1 例无恶化），其次是托吡酯，2/13（15.4%，无完全缓解和 1 例恶化）。根据我们的文献综述，唯一导致 VSS 恶化的药物是阿米替林。至少有一次报道有效的其他药物还有丙戊酸、普萘洛尔、维拉帕米、巴氯芬、萘普生和舍曲林。使用黄色-蓝色光谱的彩色滤光片的非药物方法也可能对一些患者有帮助。
视觉雪综合征仍远未被完全理解。就病理生理学而言，很可能是一种视觉处理障碍。最有药理学证据的是拉莫三嗪，可以讨论其标签外使用。作为非药物治疗的选择，患者可能会受益于日常使用的有色眼镜。
