Self Help

Migraine headaches produce chemical chain reactions that are far more complex then those that cause tension headaches. A migraine begins when the blood vessels deep inside the brain constrict because a hormone called serotonin is excreted by blood platelets. Platelets are blood components smaller than red blood cells that are part of the body’s protective clotting system. If platelets don’t stick to each other and the blood vessel walls after an injury, bleeding is dangerously prolonged. But if they clump too quickly, clots may form too readily within the blood vessels. When these clots break loose, heart attack and stroke can result.

The presence of serotonin sets off the production of two other chemicals: thromboxane and prostacyclin. Thromboxane goes to work first, helping serotonin to narrow the brain’s blood vessels abruptly. The hormonal combination of serotonin and thromboxane dramatically decreases blood flow in the brain and causes the aura stage of migraine.

In the second stage of a migraine attack, serum serotonin levels drop drastically, and the blood vessels of the skull dilate quickly, causing the intense, pounding pain of a migraine headache. The pain is throbbing because the blood pulses through the swollen arteries in time with the pulsing of blood from the heart. Prostacyclin contributes to this process by
forcing the blood vessels to dilate still further.

Finally, in the third phase of a migraine, the post-headache phase, the throbbing headache gradually subsides and is replaced by a constant unwavering pain. The blood vessels tend to become thicker and more rigid. As the headache goes on, thromboxane and prostacyclin convert to other hormones, prostaglandins. These cause the artery walls to become inflamed and thicken, often leading to visible swelling of blood vessels on the scalp, temples, or back of the neck. Although the migraine headache is over, the pain isn’t.

The prostaglandins have also caused the nerve endings in the head and scalp area to become sensitized, often so badly that just combing the hair is painful. There’s an important distinction here between blood vessel dilation and blood vessel inflammation. If you sit in a very hot bath, for example, the blood vessels in your head will dilate, but you won’t suffer a migraine.

During a migraine attack, however, the blood vessels not only dilate but also become inflamed. It’s a sterile inflammation, which means that the blood vessels become inflamed without the presence of infection. It is the combination of inflammation and pressure on distended blood vessel walls that causes the pain of migraine.

Despite the fact that the “serotonin-release” theory of migraine has been popular among researchers for more than three decades, it’s clear that the activity of serotonin cannot be the only mechanism that causes migraines.