What is it?
Migraine is a disorder characterized by recurrent headaches that are moderate or severe. The headaches typically affect one half of the head, are pulsating, last from 2 to 72 hours, and can be associated with other symptoms like nausea and oversensitivity to things like light and sound.
About 60% of sufferers experience symptoms like alterations in mood or fatigue before the headache. About one third of people experience an aura before or during the headache- this can be visual, sensory or motor in nature, and include things like seeing a flickering light in one part of the visual field, or feeling tingling or numbness on the skin.
Migraine is very common. It affect about 15% of people,and is more frequent in women than in men. It is most common during young adulthood.
What causes it?
The exact cause of migraine is not known, and the answer is unlikely to be very simple. It does, however, probably involve both genetic and environmental factors. Genetics are thought to account for just under half of the risk, and many different genes are involved. Some events might trigger an episode, and things like psychological stress, eating certain foods, and hormonal changes especially in women might contribute.
What happens during it?
The mechanism of migraine is not fully understood. It is thought that the process starts from the brain’s nerve cells and then spreads to blood vessels. The following explanation is based on one of the most popular theories.
First, increased electrical activity starts at one point of the cerebral cortex (the outer layer of our brain associated higher cognitive functions and all senses). It starts slowly spreading throughout the brain like a thunderstorm. When it has passed an area, it leaves behind exhausted neurons that are not capable of normal electrical activity. The aura that many people with migraine experience before the headache, usually starts with colorful, flickering figures and then turns into dark areas. The colorful spots are thought to appear when the electrical storm reaches the parts of our cortex responsible for sight, and the dark ones are thought to appear when the storm moves on leaving an area of decreased electrical activity.
The brain doesn’t feel pain, but the meninges (they layers that cover it) and the blood vessels in these layers do. It has been found that stimulating the vessels in the meninges leads to a migraine-like pain. When these vessels are hurt, a nerve called TGN carries the information from the meninges to the parts of the brain that turn the impulse into sensation. It is now thought, that the spreading electrical storm might stimulate the TGN to react as if the blood vessels in the meninges were damaged.
How can it be treated?
Migraine management focuses on three things: avoiding triggers, managing the headaches when they arrive, and preventing episodes. During the headache, lying down in a dark room, eating painkillers, and avoiding physical stress might help. Episodes can also be prevented through some medications.
Sources: http://www.blackwelleyesight.com/migraine-mechanism-in-detail/, https://en.wikipedia.org/wiki/Migraine#Pathophysiology, http://www.nhs.uk/Conditions/Migraine/Pages/Treatment.aspx, http://emedicine.medscape.com/article/1142556-overview?pa=Mqk8UlI9LSuSysWMWoR%2BU4XtTYoXePnH847fMcxukTHbRlBGxYNSosIe4%2Fug02F343mU9jD%2B1DtnxY47OmyybA%3D%3D#a3, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3444225/