Scientists have learned a lot in recent years about what happens in the brain to explain the throbbing pain, nausea, heightened sensitivity to light or sound felt during a migraine headache and the mysterious ‘aura’ that both doctors and scientists use to describe the telltale period, starting up to an hour before a migraine attack, when a person sees dots, wavy lines, flashing lights, blind spots or difficulty with speech, sensation, or movement.
What triggers a migraine attack?
Although researchers don’t understand exactly what triggers migraine attacks, they do know that certain foods, lack of sleep, changes in weather, and even stress can trigger a migraine attack in 1 in 200 people.
The anatomy of a migraine attack
Neuroscientists now see migraine as firstly a disturbance in nerve function rather than a disorder of the brain’s blood vessels. It is believed that in most patients, a wave of electrical activity passing through a major nerve that collects and transmits signals to the face – the trigeminal nerve – and stimulates the release of chemicals such as CGRP and other substances that cause inflammation, makes the nerves more sensitive to pain, and causes blood vessels near the brain to expand (dilate). This nerve irritation often progresses as an electrical wave from the skin to nerves located centrally in the brain.
The key to treatment is to act quickly to stop the irritation spreading. In fact, anti-migraine drugs can offer relief only in the earlier stages of the attack, but not later, when the pain neurons in the brain have become sensitized. For this reason, patients are advised to take medication within 20 minutes of an attack and while migraine pain is still mild.
The wave that turns into a flood
A migraine attack is triggered when a wave of electrical activity that starts in the trigeminal nerve on the side of the face enters the brain and ripples across the surface of the brain. In fact, researchers have been able to demonstrate a possible link between this wave and the experience of ‘aura’ particularly as it spreads across the visual part of the brain. Several drugs used to prevent migraine attacks work by preventing this wave from spreading.
Migraine is a complex neurological condition that is classified by the World Health Organisation as the 7th most disabling disease worldwide, the 4th for women.
Migraine is the most common neurological condition in the world, affecting about 12 – 15% of people. It is three times more common in women than it is in men and is usually inherited. It is a very individual condition. Some people experience only one or two attacks per year while others suffer on a weekly basis. An attack can last from 4 to 72 hours.
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