Aura phase

An aura is a transient focal neurological phenomenon that occurs before or during the headache. They appear gradually over a number of minutes and generally last fewer than 60 minutes. Symptoms can be visual, sensory or motor in nature and many people experience more than one. Visual effects are the commonest; they occur in up to 99% of cases and in more than 50% of cases are not accompanied by sensory or motor effects. Vision disturbances often consist of a scintillating scotoma (an area of partial alteration in the field of vision which flickers and may interfere with a person's ability to read or drive.) These typically start near the center of vision and then spread out to the sides with zigzagging lines which have been described as looking like fortifications or walls of a castle. Usually the lines are in black and white but some people also see colored lines. Some people lose part of their field of vision known as hemianopsia while others experience blurring.

Sensory aurae are the second most common type; they occur in 30-40% of people with auras. Often a feeling of pins-and-needles begins on one side in the hand and arm and spreads to the nose-mouth area on the same side. Numbness usually occurs after the tingling has passed with a loss of position sense.Other symptoms of the aura phase can include: speech or language disturbances, world spinning, and less commonly motor problems. Motor symptoms indicate that this is a hemiplegic migraine, and weakness often lasts longer than one hour unlike other auras.

An aura rarely occurs without a subsequent headache, known as a silent migraine. However, it is difficult to assess the frequency of such cases, because patients who do not experience symptoms severe enough to drive them to seek treatment, may not realise that anything special is happening to them, and pass it off without reporting anything.