Migraine is a very common chronic disorder suffered by an estimated 18% of women and 6% of men. It is characterised by attacks of painful headache, and in some patients involves an aura with symptoms such as visual disturbances, numbness, weakness and speech difficulty.
Disability is a defining characteristic of migraines. The World Health Organisation ranks severe migraine as disabling as quadriplegia, psychosis and dementia. In the US an estimated 64 million days of work are lost annually due to migraines, while in New Zealand the estimate is 700,000 days.
Migraine without aura (common migraine) is defined as attacks lasting 4 to 72 hours with two or more of the following symptoms:
Unilateral pain
Throbbing
Aggravation on moving
Pain of moderate or severe intensity
And with one of the following symptoms:
Nausea or vomiting
Photophobia or phonophobia
The exact mechanism by which migraine occurs is unknown. There are several theories, which are likely to be interrelated. One of the most popular theories is that a migraine is caused when a physiological trigger in the body or the environment sets off vasodilation (expansion of the blood vessels) in the cranial blood vessels which in turn activates the trigeminal nerve endings in the brain. This activation is thought to cause the release of chemical neurotransmitters, of which serotonin (5-hydroxytryptamine or 5-HT) is believed to be the most important. Inflammation at various sites is often concurrent with migraines.
Triggers that can set off a migraine vary from person to person and include alcohol, caffeine, hormonal changes, hunger, lack of sleep, medications, glare etc. Susceptibility to migraine is highly heritable, and recent work has identified some of the genes involved.
A range of treatments is available depending upon the seriousness of the condition. Mild to moderate cases are treated by over the counter analgesics such as non-steroidal anti-inflammatory drugs (NSAID) including aspirin and ibuprofens. More severe cases are treated with pharmaceutical drugs including oral triptans, ergot derivatives, opiates and barbiturates.
Prevention is usually first approached from avoidance of triggers that can set off headaches. Other strategies employed include diet modification, exercise, physical therapy, bio feedback and dietary supplements.
For moderate to severe migraine sufferers a number of drugs are often prescribed, including beta-blockers, antidepressants and anticonvulsants.
All treatments can therefore be classed as either for acute treatment (taken at onset to relieve or eliminate the migraine) or for prevention (taken to reduce or eliminate the occurrence of migraines).
Treatment can be further classed as being a drug treatment or non drug treatment.
