Vincent Maurice B
Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Headache. 2015 Apr;55(4):595-9. doi: 10.1111/head.12531. Epub 2015 Mar 11.
Migraine, a common brain disorder, disrupts vision more than any other motor or sensory function. The possible visual aura symptoms vary from occasional small flashes of light to complex visual hallucinations, the stereotyped teichopsia being the most typical pattern. It is unclear as to why aura occurs serendipitously, sometimes preceding, but also occurring after the headache, and why aura can present with multiple phenotypes.
To better understand the nature of visual disturbances in migraine, 4 aspects must be considered: What are the visual perceptions in migraine; why vision is affected in migraine; the role of cortical spreading depression (CSD); how does vision could affect migraine. Evidence supporting each of these topics is reviewed.
CSD travels at a similar pace as the march of symptoms in the visual field. Functional neuroimaging studies show spreading changes compatible with CSD regardless of aura. Computerized models reproducing the CSD march on the visual cortex predict a sensory experience compatible with naturally occurring visual auras. Rather than spreading in all directions, these models suggest that CSD moves preferentially in one direction. Migraine-preventive drugs increase the CSD threshold and reduce CSD velocity. Blind migraineurs may present atypical visual aura, with more colors, shorter duration, different shapes, and atypical symptoms, such as auditory experiences.
CSD is the underlying phenomenon in migraine with and without aura. In migraine without aura, CSD probably does not run over silent areas of the cortex, but rather does not reach symptomatology threshold. Normal vision is important in migraine, as lack of sight may change the visual experience during migraine aura, probably due to cortical reorganization and changes in local susceptibility to CSD.
偏头痛是一种常见的脑部疾病，对视觉的干扰超过任何其他运动或感觉功能。可能出现的视觉先兆症状从偶尔的小闪光到复杂的视幻觉不等，刻板的闪光暗点是最典型的模式。目前尚不清楚为什么先兆会偶然出现，有时在头痛之前出现，但也会在头痛之后出现，以及为什么先兆会呈现多种表型。
为了更好地理解偏头痛中视觉障碍的本质，必须考虑四个方面：偏头痛中的视觉感知是什么；为什么偏头痛会影响视力；皮层扩散性抑制（CSD）的作用；视力如何影响偏头痛。对支持这些主题的证据进行了综述。
CSD的传播速度与视野中症状的进展速度相似。功能神经影像学研究表明，无论是否有先兆，都存在与CSD相符的扩散变化。在视觉皮层上再现CSD进展的计算机模型预测了与自然发生的视觉先兆相符的感觉体验。这些模型表明，CSD不是向各个方向扩散，而是优先向一个方向移动，而不是向各个方向扩散。偏头痛预防性药物会提高CSD阈值并降低CSD速度。失明的偏头痛患者可能会出现非典型的视觉先兆，有更多颜色、更短持续时间、不同形状以及非典型症状，如听觉体验。
CSD是有先兆和无先兆偏头痛的潜在现象。在无先兆偏头痛中，CSD可能不会在皮层的静息区域传播，而是没有达到症状阈值。正常视力在偏头痛中很重要，因为失明可能会改变偏头痛先兆期间的视觉体验，这可能是由于皮层重组和局部对CSD易感性的变化。
