An aura is a short-lived focal neurological phenomenon that typically occurs before or during the migraine attack. Auras tend to appear gradually over several minutes and generally last less than one hour. Symptoms can be motor, sensory, visual, or sensory in nature, and many patients experience more than one episode at a time. Visual effects are known to occur most frequently (in up to 99% of cases), while in more than 50% of cases, auras are accompanied by motor or sensory effects.
Vision disturbances usually consist of a scintillating scotoma (a term used to describe an area of partial alteration or blurring in the field of vision which may interfere with a patient’s ability to concentrate, drive or read). In a majority of cases, visual auras typically begin near the center of vision and gradually spread out to the sides. People experiencing these symptoms tell that they can appreciate zigzagging lines in the center of vision, which they describe as looking like the walls of a castle or fortifications. Usually, the lines are black and white, but some patients also see colored lines. In severe cases, some people may even lose part of their field of vision; a condition called hemianopsia.
Sensory aura is the second most common type; it occurs in 30–40 percent of patients with auras. A feeling of pins-and-needles often begins on one side of the hand and arm and spreads to the nose-mouth area. Other symptoms of the aura phase may include world spinning, speech or language disturbances, and motor problems.