Migraine Aura: Warning about an Impending Attack

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 or, even 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 can be the result of changes taking place in the cortex or the brain's outer layer. The brain has nerve cells which are always active and they generate electrical activity and, it is believed that when increases or decreased nerve cell activity takes place in the brain of a person suffering from migraine, following a migraine trigger, then the migraine aura appears.

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 left to right side of the body. Migraine aura may cause a person to notice a black spot in their vision and, the black spot may have corresponding flashing lights or bright crisscrossing lines. As minutes pass, the black spot becomes larger and, the typical migraine aura will consist of loss of vision as well as flashing lights and, crisscross lines.

There is not a complete understanding as to what exactly is the cause of the sequence of events that precede the migraine aura. It is known that it could be due to inborn vulnerability or due to changes in the body's chemistry like menstruation, consuming some food types as well as changes to the environment such as weather, all of which may trigger a migraine attack. When internal or external events cause different nerves of the brain to be stimulated and, such stimuli are relayed to nerve centers in the brain it may cause the nerve impulses sent to the cortex of the brain into causing a migraine aura.