Here's intriguing evidence that certain structural changes in the brain may be related to chronic migraines.
Can we use MRI to tell us someone has migraines?
Not yet . . . but the possibility is getting closer.
Some of my colleagues consider the “lack of objectivity” in headache medicine to be frustrating. Despite significant improvement in our understanding of pathophysiology of migraines and its effective treatment, this “subjective” view of headache persists among my colleagues.
What is “objectivity”? Well, I guess it depends on whom you ask. Some consider imaging studies one of the best ways to be “objective.”
A new study by Schwedt and colleagues1 involved looking at detailed MRI images of the brain in patients with and without migraine. The magnetic strength of the MRI scanner was higher than is available to most of us (at 3 Tesla), but the findings helped confirm some of our current clinical suspicions about migraines.
The authors looked at the brain MRI images of 120 patients, 54 without migraine and the rest with. Excluded from this study were:
. Patients who were taking migraine preventative medications
. Those who met criteria for medication overuse headache (MOH)
. Those taking opioids
. Persons with neurologic conditions other than migraine
Fifteen migraineurs were considered to have “chronic” migraine based on the current International Classification of Headache Disorders. The authors compared cortical thickness, surface area, and regional volumes in different areas of the brains of those with and without chronic migraines. Several areas of abnormality were seen consistently in patients with chronic migraine relative to migraineurs without chronic migraine and in those without headache. These areas were typically located in the anterior cingulate cortex, entorhinal cortex, temporal pole, and transverse temporal gyrus.
The authors were able to subdivide the migraneurs based on frequency of days of headache and the above structural abnormalities. Those with high frequency of migraines, (ie, chronic migraineurs, defined by current ICHD criteria of having at least 15 headache days per month) were most identifiable by these structural abnormalities. Although 15 days per month was the most obvious cutoff in allowing differentiation of the migraineurs, lower frequencies of headache days (et, 5 headache days per month and also 9 headache days per month) helped separate the different migraineurs.
Does this mean we will be able to tell whether someone truly has migraines based on an “imaging study”? Maybe . . . in the future.
What does it all mean?
To me, this study suggests that certain brain abnormalities may be related to migraines. Are they caused by migraines? This question cannot be answered by this study, but the findings suggest a relationship. The true implication of these abnormalities is not known, but it appears that such changes are not normal and--to my mind--not desired.
This study excluded patients who were being treated with migraine preventative medications. It would be interesting to go back to some of those excluded patients with prior “chronic migraine” (based on historical data) and-with good or adequate control with migraine preventative medications-and compare their brain structure with that of untreated patients.
How do migraine-specific acute therapies affect these results? Although unknown, it would be interesting to find out how many of migraineurs in this study were using triptans-and how often. Even when excluding patients who met criteria for medication overuse headaches, such patients would be allowed to use these medications. Does this change the subcategories noted above? Can a preventative or protective effect be suggested by these medications? For now, only future studies hold these answers.
What about objectivity in headache medicine? For me, the structural changes found by this study point to the “objective” nature of migraine headaches.
1. Schwedt T, Chong C, Wu T, et al. Accurate classification of chronic migraine via brain magnetic resonance imaging. Headache. 2015;55:762-777.