Migraine Aura: New Ideas About Cause and Significance
Migraine Aura: New Ideas About Cause and Significance
The fact that aura is a variable feature of a migraine attack for many patients raises questions about whether it plays an essential role in triggering headache. Although it is possible that the brain phenomenon underlying aura could occur without generating clinical symptoms ('silent aura' – see next section), it seems more likely that this phenomenon is in fact not occurring at all in the majority of migraine attacks. It is also common for aura to occur without subsequent headache, particularly in older men. Thus, aura is neither necessary nor sufficient for headache.
Recent studies also suggest that the timing of aura relative to headache may not be as consistent as previously believed. Examination of the results of a clinical trial that prospectively recorded aura symptoms in conjunction with other migraine attack symptoms found that a majority of patients reported headache, as well as other defining migraine symptoms at the same time that they reported onset of aura. These results contradict the widely held idea that migraine aura consistently precedes headache.
The occurrence of premonitory symptoms prior to any other migraine symptoms also suggests that aura is not a primary trigger for a migraine attack. During premonitory symptoms, changes in brain activity can be seen on PET scans even hours before headache – thus occurring at a time clearly preceding classical aura. A recent study investigated interictal resting-state functional brain connectivity in migraine with aura patients and found no abnormalities of intrinsic brain connectivity. Taken together, these observations indicate that the aura is not a fundamental initiating event of a migraine attack. Rather, it seems more likely that the aura is a variable component of an aberrant 'brain state' that occurs during a migraine attack.
Does Migraine Aura Trigger Headache?
The fact that aura is a variable feature of a migraine attack for many patients raises questions about whether it plays an essential role in triggering headache. Although it is possible that the brain phenomenon underlying aura could occur without generating clinical symptoms ('silent aura' – see next section), it seems more likely that this phenomenon is in fact not occurring at all in the majority of migraine attacks. It is also common for aura to occur without subsequent headache, particularly in older men. Thus, aura is neither necessary nor sufficient for headache.
Recent studies also suggest that the timing of aura relative to headache may not be as consistent as previously believed. Examination of the results of a clinical trial that prospectively recorded aura symptoms in conjunction with other migraine attack symptoms found that a majority of patients reported headache, as well as other defining migraine symptoms at the same time that they reported onset of aura. These results contradict the widely held idea that migraine aura consistently precedes headache.
The occurrence of premonitory symptoms prior to any other migraine symptoms also suggests that aura is not a primary trigger for a migraine attack. During premonitory symptoms, changes in brain activity can be seen on PET scans even hours before headache – thus occurring at a time clearly preceding classical aura. A recent study investigated interictal resting-state functional brain connectivity in migraine with aura patients and found no abnormalities of intrinsic brain connectivity. Taken together, these observations indicate that the aura is not a fundamental initiating event of a migraine attack. Rather, it seems more likely that the aura is a variable component of an aberrant 'brain state' that occurs during a migraine attack.
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