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Migraine
Aetiology
A variety of environmental and chemical stimuli may "trigger" the onset of migraine  attacks in susceptible persons. This sensitivity seems at least in part to be genetically determined since migraine with aura is four times more common and migraine without aura is twice as common in the first degree relatives (parents, siblings and children) of affected individuals as in the normal population. The trigger factors are not the cause of migraine but they initiate attacks in people who have the genetic predisposition to migraine. Not all migraines have the same provoking factors.
Migraine triggers include:
- physical and psychological stress
- alcohol
- foods containing tyramine, such as ripe cheeses and red wine
- foods containing monosodium glutamate (MSG), such as prepared frozen foods
- chocolate
- foods containing nitrates, such as preserved meats
- caffeine withdrawal
- irregular sleep patterns
- fluctuating hormone levels in women, e.g. during menstruation or at the menopause
- environmental factors, e.g. weather or temperature changes.
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What happens in the brain?
Migraine attacks seems to involve neuronal as well as vascular changes and it may therefore be considered to be a neurovascular disorder. During the migraine aura, characteristic changes in cerebral blood flow have been observed. It is most likely that these transient changes are secondary to altered activity in neurons of the cerebral cortex . Migraine pain seems to involve alterations in the regulation of tone in the cranial vasculature. The nature of these alterations is not clearly defined. A sterile inflammatory process which involves the liberation of several neuropeptide may increase the diameter of blood vessels and increase the sensitivity of the pain sensing nerve endings around the cranial blood vessels. These mechanisms may be initiated by changes in the concentrations of certain neurotransmitter, particularly serotonin (5-HT), calcitonin gene-related peptide (CGRP) and nitric oxide (NO) in the brain.
 Further information on cerebral vasculature
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