A migraine is a primary headache disorder characterized by recurrent headaches that are moderate to severe.Typically, the headaches affect one half of the head, are pulsating in nature, and last from two to 72 hours. Associated symptoms may include nausea, vomiting, and sensitivity to light, sound, or smell.The pain is generally made worse by physical activity.Up to one-third of people have an aura: typically a short period of visual disturbance that signals that the headache will soon occur.Occasionally, an aura can occur with little or no headache following it.
Migraines are believed to be due to a mixture of environmental and genetic factors.About two-thirds of cases run in families.Changing hormone levels may also play a role, as migraines affect slightly more boys than girls before puberty and two to three times more women than men. The risk of migraines usually decreases during pregnancy.The underlying mechanisms are not fully known.They are, however, believed to involve the nerves and blood vessels of the brain
Signs and symptoms
Migraines typically present with self-limited, recurrent severe headache associated with autonomic symptoms. About 15–30% of people with migraines experience migraines with an aura and those who have migraines with aura also frequently have migraines without aura. The severity of the pain, duration of the headache, and frequency of attacks are variable. A migraine lasting longer than 72 hours is termed status migrainosus.There are four possible phases to a migraine, although not all the phases are necessarily experienced:
The prodrome, which occurs hours or days before the headache
The aura, which immediately precedes the headache
The pain phase, also known as headache phase
The postdrome, the effects experienced following the end of a migraine attack