Headaches

Migraine Aura: Warning about an Impending Attack


Defined Tag: Migraine Headache.

A warning that a migraine is about to come on causes a change in the functioning of the brain and is referred to as a migraine aura. The symptom may be visible and, may take the form of a curved sparkling crisscross line, or the vision may blot out, or both. There may be other signs as well including numbness on either the left or right side of the face and hands, weakness, altered consciousness or unsteadiness. For quite some time, these symptoms were believed to be due to spasms of blood vessels supplying parts of the brain.

Changes in the Cortex of the Brain

Migraine aura appears to the result of changes taking place in the cortex or the brain’s outer layer. The brain has nerve cells that are always active. When their activity level changes (increases or decreases), they can trigger a migraine, causing the aura effect described above.

Decreased activity of the nerve cells may cause impairment in the functioning of the part of the body controlled by such cells and, may lead to loss of vision or strength. On the other hand, increased activity of brain nerve cells can cause flashing lights or tingling in the face and hand. The typical migraine aura can be induced by a slow spreading of depressed nerve cell activity.

With migraine aura, symptoms can grow gradually and may transfer from visual regions or from the left to the right side of the body. Migraine aura may cause a person to notice a black spot in their vision with corresponding flashing lights or bright crisscrossing lines. As minutes pass, the black spot becomes larger, encompassing the entire visual field.

There is no consensus on the cause of a migraine aura; leading theories include an inborn vulnerability, or changes in the body’s chemistry like menstruation, consuming some food types, or reactions to external stimuli, such as weather, atmospheric pressure, or strong scents. When internal or external events cause different nerves of the brain to be stimulated, sending nerve impulses to the cortex of the brain, causing a migraine aura.