A migraine headache is a form of vascular headache. Migraine headaches are caused by vasodilatation (enlargement) of blood vessels and the release of chemicals from nerve fibres that coil around the large arteries of the brain. This enlargement stretches the nerves and causes them to release other chemicals which cause inflammation, pain, and further enlargement of the artery, making things worse. There are many causes of migraine and many people are never sure what causes them. They may be associated with prodromal symptoms like stiff muscles, diarrhoea or constipation.
Migraine attacks commonly activate the sympathetic nervous system in the body which controls primitive responses to stress and pain, the so-called “fight or flight” response. This activation causes many of the symptoms associated with migraine attacks, nausea and vomiting, for example.
Migraines are a form of vascular regulation abnormality and are thought to be associated with an increased risk of glaucoma. A migraine headache is affects one half of the head and is pulsating in nature. It lasts from 4 to 72 hours; symptoms include:
- Nausea and vomiting
- Photophobia (increased sensitivity to light)
- Phonophobia (increased sensitivity to sound)
Approximately a third of people who suffer from migraines get an aura or visual prodrome which is an unusual visual, olfactory, or other sensory experiences that are a sign that the migraine will soon occur. These episodes may last for 20 minutes to a couple of hours and usually happen just before the onset of the other symptoms.
There is often also a postdrome phase after the event where migraine sufferers feel tired, depressed or hungover and may experience cognitive impairment and trouble concentrating.
It is recommended that first episode migraines are thoroughly investigated to eliminate other causes of the visual symptoms when noticed. Flashes and floaters associated with retinal detachment may appear similar. Strokes and other cerebral vascular events may also create a similar experience. A thorough vision examination is recommended which includes evaluation of neurological visual fields.
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