Dr. Andrew Charles and his associates at UCLA just published a fascinating report on migraine aura in the journal Brain. We still do not understand the brain mechanisms that lead to the phenomenon of migraine aura. The published report characterizes a large number of visual auras recorded by a single individual over nearly two decades. This person made detailed drawings of his visual aura in real time during more than 1000 attacks of migraine aura. His auras were never followed by a headache. The drawings showed the shape and location of the aura wavefront or blackout areas in the visual field with one minute intervals. These drawings were digitized by the researchers to make it easier to analyze them. Consistent patterns of aura initiation, propagation and termination were observed in both right and left visual fields. Most aura attacks started centrally, but some also started in the periphery, which in most people is more common. The auras that started centrally moved down and in first and then up and to the side. The speed of progression of the auras was always the same. The speed was about 2-3 millimeters per minute, which is what has been reported by most other people in the past. Some auras started and then quickly stopped without progressing. In some episodes the visual aura disappeared for several minutes before reappearing in a distant location, suggesting that the aura can be clinically ‘silent’. The authors concluded that these results indicate that there can be multiple distinct sites of aura initiation in a given individual, which has never been established before. They also stated that the visual perception of migraine aura changes depending on the region of the brain’s occipital cortex that is involved. This study is another small contribution to the unraveling of the puzzle that is migraine headache.
