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MigraineAetiologyA 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. 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.
What happens in the brain?Migraine attacks seem 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 neuropeptides may increase the diameter of blood vessels and increase the sensitivity of the pain sensing nerve endings around the cranial blood vessels. These processes may be initiated by changes in the concentrations of certain neurotransmitters, particularly serotonin (5-HT), calcitonin, gene-related peptide (CGRP) and nitric oxide (NO) in the brain.
Last updated: 20.12.2011 |
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