Neurologists often refer their patients with headache for a brain MRI scan. Quite often the reason for this is to reassure their patients who are worried about a sinister cause for their headache…and the anxiety provoking culprit is usually a brain tumour. The headache is often a migraine which has recently changed in character, or which is defying conventional treatment.
The neurologist is often ambivalent when requesting such scans. On the one hand, she expects the scan to be normal. On the other hand, she can not be certain there is indeed no sinister cause for the headaches. Another thing also bothers the neurologist, beyond the chance of detecting a brain tumour. And this is the ‘risk’ that the brain scan detects ‘incidental’ findings called white matter lesions (WML). Alas, these reassurograms frequently pick up these less sinister, but nevertheless unexplained, findings.
White matter lesions are often just age-related, ‘wear and tear’ changes, and they are more common in people with vascular risk factors such as hypertension, smoking and raised cholesterol levels. Neurologists generally believe migraine is also a risk factor for white matter lesions. And there are several studies to support this belief.
An example is a paper by the headache gurus Marcelo Bigal and Richard Lipton, published in the journal Cephalalgia, titled migraine as a risk factor for deep brain lesions and cardiovascular disease. Another is a paper by Kruit and colleagues in the Journal of the American Medical Association (JAMA) titled migraine as a risk factor for subclinical brain lesions. If you are still not convinced, try this article in the Archives of Neurology by Swartz and colleagues, with the unequivocal title-migraine is associated with magnetic resonance imaging white matter abnormalities.
With this strong evidence, neurologists are able to convince themselves there is nothing to these MRI high signal changes in their patients with migraine. No ‘chicken and egg’ philosophical equivocation is entertained. The scans are sometimes discussed at neuroradiology meetings where everybody murmurs ‘migraine white matter lesions’. All doubt dispelled, the neurologist reassures the patient, and hurriedly closes the chapter.
It is therefore with a strong jolt that neurologists read a recent article in the prestigious journal, Brain, greatly upsetting this cosy neurological consensus. In the paper titled migraine with aura and risk of silent brain infarcts and white matter hyperintensities, the authors found no association between migraine and brain white matter lesions. Shocking!
The authors studied female twin pairs aged between 30–60 years. The twins were identified through the population-based Danish Twin Registry. The authors compared the MRI scans of the subjects with and without migraine, and found no difference in the frequency of white matter changes between the two groups. They proudly, and disconcertingly, declare that ‘we found no evidence of an association between silent brain infarcts, white matter hyperintensities, and migraine with aura‘.
Oh dear-what do neurologists tell their patients now? I shudder to think!