Aura with headache.

Typical migraine aura is a short-lived sensory experience coming before or during migraine and experienced by about 1/4 of all migraineurs. The experience can be visual, sensory, or result in problems with speaking or word finding. Typical visual changes are seeing spots, zigzags or crescents, flashes of light, or losing sight partially or fully, with any one of these lasting between 5 minutes and one hour. The symptoms, when they first occur, can be alarming. However, usually, typical migraine aura is a recurring and completely reversible phenomenon that heralds the onset of a migraine. Those affected sometimes use the aura symptoms as a signal for effective early treatment of the headache. There are treatments that can reduce the intensity or frequency of aura, and many times, the migraine itself can be improved by treating the aura. Visual changes are the most common form of aura, occurring in more than 90% of those migraineurs with aura. There can be spots, either colored or dark, circles increasing in size, zigzags, or crescent shapes, and light or dark alterations of vision. It is not uncommon to experience tunnel-like vision such that the sides of the visual field are darkened. When people see zigzags or crescents, this is termed a “positive” visual phenomenon. When people simply lose vision and see only black or dark, this is termed a “negative” phenomenon. The zigzags often assume the shape of forts from the Middle Ages and are referred to as “zigzag fortification spectra.” The shimmering that occurs in aura when vision is obscured is referred to as a “scintillating scotoma,” where a scotoma is a blind spot in vision. Sensory changes are the second most frequent form of typical migraine aura. These may consist of tingling or numbness on one side of the face, body, or tongue. Usually, the sensation change begins in the fingers and moves up the arm and then up to the chin and tongue in what is called a “cheiro-oral” aura. A third form of typical aura results in problems with speech or language, such as being temporarily unable to speak, slurred speech, being unable to find the right word, or using the wrong word to express an idea. All 3 common types of aura, and different symptoms within each type of aura, are considered typical if any one of them lasts less than an hour. Typical aura is not accompanied by actual weakness of the affected area, although sometimes migraineurs confuse extreme numbness as weakness. True weakness, such as being unable to lift an arm, is attributed to a more rare form of migraine aura, hemiplegic migraine. Aura is caused by a firing of nerves in the brain that serves a particular function. For example, a visual aura is caused by nerves firing in the visual cortex of the brain and is associated with a big increase in blood flow to serve the activated nerves. When the firing is complete, the nerves become quiet, and the blood flow drops because the nerves are no longer firing. This period of decreased blood flow is referred to as “cortical spreading depression,” but aura is really a spreading activation, with the depression only occurring after the activation. One common misconception is that other symptoms signaling an impending migraine represent aura. These symptoms, called Headache: The Journal of Head and Face Pain © 2014 American Headache Society Published by John Wiley & Sons, Inc. doi: 10.1111/head.12379