‘Migraine increases the risk of brain damage’

People suffering from migraine have an increased risk of incurring brain damage. Neuroradiologist Mark Kruit came to this conclusion after having put hundreds of Dutch citizens through an MRI scanner. There is no reason for panic yet, as we do not know what the effect will be. He defended his doctoral dissertation on 20 January.

People suffering from migraine have an increased risk of incurring brain damage. Neuroradiologist Mark Kruit came to this conclusion after having put hundreds of Dutch citizens through an MRI scanner. There is no reason for panic yet, as we do not know what the effect will be. He defended his doctoral dissertation on 20 January.' Mark Kruit: ‘It may sound harsh, but there really is nothing we can do about it, nor is it clear whether we need to do anything.’

Risk factor

At least ten per cent of the Dutch population is at times plagued by migraine. And that does not mean by an occasional minor headache. The average rate of attacks is between once and twice a month. Three times as many women suffer from migraine as men. In a small subgroup, migraine even worsens into a chronic headache. It should be clear that the scope of the problem is large. The question that interests Kruit is whether migraine can cause neurological collapse. More specifically: is migraine an independent risk factor for brain damage?

Minor infarctions

In 1999 and 2000, Kruit conducted a study which involved doing an MRI scan on 295 migraine sufferers and 140 people who had never had migraine. In no less than eight per cent of the migraine sufferers with an aura (symptoms that can vary from light flashes to insensitivity) minor infarctions were visible in the cerebellum, the area that controls equilibrium and fine-tunes motor control. In the group of migraine-free people, less than one per cent had these small infarctions. ‘This became visible because we were working with more accurate MRI scans than was previously customary,’ Kruit explains. ‘In older research, they scanned thicker slices, if I may call them that. We scanned slices of only 3 millimeter.’

Media attention

In the scan the minor infarctions looked like small holes. That was where tissue had died, presumably due to a lack of blood and oxygen. ‘The world responded to these results at once,’ Kruit says. ‘When we published the first results of our research, five years ago, we got massive media exposure. That’s flattering on the one hand, but disturbing on the other. Headlines shouting things like ‘Migraine punches holes’ caused outright panic among patients. Doctors in their surgeries were flooded with questions. The panic is understandable; unfortunately, there is still no answer that is completely reassuring. Remember that it is still not clear what the functional consequences are of brain damage.’

Image – Transversal 3mm FLAIR shot showing several focal hyperintense lesions in white matter (arrows)

Consequences

Those patients who had been diagnosed with having brain damage have not noticed any obvious negative effects. But that does not mean that all is well. Kruit: ‘Other studies, conducted among non-sufferers, have taught us that infarctions and white-matter damage often go hand in hand with a diminished functioning of the brain. Further research is needed to find out how migraine sufferers are affected. We should say first that that the amount of brain damage we discovered is relatively limited. It is not yet clear whether there is a progression of the damage as attacks increase; that, too, has yet to be researched. What’s more, at this moment there is no effective treatment. It may sound harsh, but there really is nothing we can do about it, nor is it clear whether we need to.’

Scars

The second form of brain damage Kruit noticed consisted of small white spots or scars in the white matter of the brain, the axons connecting the brain cells. The cause of these scars is not known, nor is their effect. What he was able to establish is that white-matter damage occurs twice as often in women of childbearing age who suffer from migraine than in women who don’t. Women with a high frequency of attacks who smoke, have high blood pressure, or take the contraceptive pill appear to be at an even higher risk. There is no increased risk of damage to the white matter for men with migraine.

Frequency of attacks

Even though it has been established that people suffering from migraine run a higher risk of incurring brain damage than people free from migraine, it has still not been proved that brain damage is actually caused by migraine. But it has become a lot more likely, Kruit believes: ‘The good thing about this study is that we have shown that the risk of brain damage increases if there is a higher frequency of attacks or a longer record of migraine. This could indicate a causal correlation, but is not conclusive proof. If someone were ever to prove that migraine causes lasting and increasing damage, it would mean that migraine is more than an annoying but passing condition. This might also necessitate a change in our methods of treatment. More research is needed into both the causes and the effects of that brain damage. So that is what we are engaged in now.’

Doctoral defence: Wednesday 20 January
Mark Kruit
Migraine and Brain Lesions
Faculty of Medicine
PhD supervisors: Professor M.A. van Buchem and Professor M.D. Ferrari

(19 January 2010)