While the cause of migraines have not yet been determined, scientists believe that migraines result from a combination of vascular (veins and arteries) and neurologic (nerves) events. Four theories have been created to explain the cause of migraines:

• Traditional theory
• Central theory
• Neurogenic theory
• Unifying theory of the three stated above

Traditional theory

Now considered an over-simplification of the cause of migraines, scientists first introduced the traditional theory in the 1930s. The traditional theory suggests that migraines occur because the veins and arteries outside of the skull expand and the veins and arteries inside the skull contract, causing pressure and pain.

Central theory

The central theory suggests that migraines result from an imbalance of magnesium and hormone levels in the brain. Researchers believe that an attack is initiated by low magnesium levels in the body that eventually create abnormal electrical activity and a disturbance in the hormone called serotonin in the brain.

Neurogenic theory

The neurogenic theory suggests that migraines result from a reaction between the nerves and arteries that control the face, eyes, nose, mouth, and jaws (the trigeminovascular system). Researchers believe that pain increases at the base of the trigeminovascular system in the brain when the protective covering around the brain and spinal cord becomes inflamed due to expansion or contraction of arteries.

Unifying theory

A unifying theory attempts to put these three interrelated theories together. This unifying theory suggests that migraines begin as a disturbance in the electrical activity in the brain, which causes changes in the brain stem and the trigeminovascular system.² Again, these theories have yet to be proven, but much research is being conducted to discover the cause of migraine headaches.