How do the brain activities in migraine change?

Brain activity in migraine aura studied

Migraine is characterized not only by headaches, but is also accompanied by a part of those affected by so-called aura symptoms. However, what mechanisms in the brain trigger these symptoms has remained largely unclear. Now scientists of the Danish Headache Center, the Department of Neurology of the University of Copenhagen and the University Eye Hospital Magdeburg have analyzed the brain activity in patients with migraine aura and discovered conspicuous patterns.

The migraine aura shows, for example, in the form of visual disturbances, which can be of different nature and ranging from the perception of flickering flashes to visual field defects, reports the University Hospital Magdeburg. However, the underlying mechanisms of aura symptoms remain largely unclear. In the current study, the scientists have now examined the brain activity of migraine patients using magnetic resonance imaging (MRI) and identified conspicuous patterns. Their results were published in the journal "Annals of Neurology".

Migraine aura affects about one third of patients

Migraine is mainly known for recurring severe headaches, however, may also include other complaints that are summarized under the term migraine aura. "About ten percent of the total population suffers from migraine attacks and a third of them experience the so-called migraine aura," according to the announcement of the University Hospital Magdeburg. This is manifested, for example, by impaired vision. The underlying mechanisms are still not well understood.

Magnetic resonance tomography for measuring brain activity

Magnetic Resonance Imaging (MRI) allows not only the assessment of brain anatomy, but also of brain activity, and thus this approach could provide access to the neural mechanisms of visual symptoms, the researchers argue their research approach. However, because of the unpredictable short-lived nature of the aura, it is very difficult to conduct systematic studies on patients during an aura. In fact, so far there has only been one study in which the aura of a patient has been analyzed in detail with the help of MRI scans. The study found signal changes in the brain consistent with the aura characteristics. "However, this has neither been repeated nor confirmed," the researchers report.

Patients examined during aura attacks

So many questions about the pathophysiology of the aura and its relationship to migraine remain unanswered. The current study by the international team of researchers began here to contribute to a better understanding of the migraine aura. "Using functional magnetic resonance imaging (fMRI), they examined five patients during aura attacks," reports the University Hospital Magdeburg. The aura was specifically triggered by inhalation of air with reduced oxygen, by atmospheric air or by sport combined with light stimulation. "Once the patients reported the onset and progression of visual disturbances, they were immediately examined in the MRI scanner," explain the scientists. The researchers measured the responses of the visual cortex of the brain to moving checkerboard patterns.

Functional changes in the brain detectable

The researchers found that different aura symptoms reflected different functional changes in the brain and, for example, patients with visual aura symptoms such as visual field defects, decreased responses of the visual cortex, while patients who experienced flashes of light and flicker showed increased responses. If both halves of the visual field were affected by the visual symptoms, "the changes in the activity of the visual cortex were also observed in both halves of the brain"; explain the researchers further. This proved that different aura symptoms are associated with different responses of the visual cortex. This represents an important step towards a better understanding of the migraine aura and hopes for new approaches to effective treatment, the scientists conclude. (Fp)