What is a migraine?
In general, a migraine is a type of headache. However, the term migraine also includes a number of broader symptoms that occur elsewhere in the body, either before or at the same time as the headache.
- A moderate to severe throbbing headache, lasting from several hours to a few days.
- The headache may be preceded by an aura (see below).
- The pain is typically centred over one eye or temple, or the back of the head, but it may involve both sides of the head.
- Nausea and sensitivity to light and noise often accompany the headache.
- Generally, the migraine prevents you taking part in your usual activities, whether work or pleasure.
A migraine may be preceded by a group of symptoms related to your nervous system, for example, visual changes (e.g. seeing white spots or zig-zag lines in your field of vision), dizziness, feeling pins and needles or, less often, ringing in your ears. Rarely, other symptoms such as speech problems, and even weakness may occur. This group of symptoms is called an aura, and divides migraines into 2 groups: migraine with aura and migraine without aura. Most people who get migraines do not have an aura before the headache.
Who gets migraine?
Migraines tend to run in families. They can occur during childhood, affecting boys and girls equally. After puberty and in adults, migraines are 2-3 times more common in women than in men, and female hormones are thought to play a role in triggering migraines. For example, many women get migraines around the time of their period or at ovulation, when their hormone levels are fluctuating.
Up to 15 per cent of adults get migraines.
What causes migraine?
The well-known trigger factors for migraine, such as a lack of sleep or certain foods, don’t actually cause the migraine on their own, but they do aggravate it. Some experts now believe that the cause of migraine in susceptible people is a chemical signal that triggers pain sensors along the trigeminal nerve, a nerve which supplies the tissues of the cheeks, jaw and forehead. This chemical signal causes:
- inflammation of blood vessels in the head; and
- widening of blood vessels in the head.
This process irritates local nerve fibres, and sends pain signals back to the brain. It is also thought that the brain chemical serotonin plays a role in this process.
A migraine can be aggravated or ‘triggered’ by several different factors, including:
- missing a meal;
- lack of sleep;
- certain odours;
- certain foods including cured meats, chocolate, caffeine, nuts, pickled foods, monosodium glutamate (MSG), aged cheese, yogurt, onions, brown vinegar, chicken livers, among many others;
- hormone fluctuations;
- some medicines including birth control pills;
- overuse of pain-relieving medicines.
Not everyone who gets migraines shares the same triggers. Keeping a food and pain diary can be helpful for working out which foods, if any, trigger your migraines.