March 27, 2013
Breakthrough Study Links Migraines To Abnormalities In Brain’s Cortex
Alan McStravick for redOrbit.com - Your Universe Online
The prevailing science on the subject of migraine headaches had long recognized that certain people are simply more likely to be afflicted by this potentially debilitating condition than others. In fact, the Mayo Clinic details a handful of risk factors that can make someone more or less likely to experience migraines. Among the recognized risk factors are family history, age, gender and hormonal changes.
While these and other risk factors have long been recognized and studied, the underlying cause behind migraines has been poorly understood at best. Now, however, a new study has linked the condition to brain abnormalities in the individual experiencing them. These abnormalities can exist from before birth or can be the result of later developmental issues.
The new study and its findings, published online in the journal Radiology, was conducted by an Italian team of scientists from University Ospedale San Raffaele and the University Vita-Salute's San Raffaele Scientific Institute in Milan.
The World Health Organization (WHO) estimates that some 300 million people around the world suffer from migraines. That figure is only slightly lower than the entire population of the United States. When a migraine comes on, the symptoms can include intense, throbbing headaches that are often accompanied by nausea, vomiting and an increased sensitivity to light and sound.
This new study builds on previous research detailing how migraine patients commonly display atrophy of cortical regions in the brain related to pain processing, possibly due to chronic stimulation of those areas. The term cortical refers to those areas associated with the outer layer of the brain known as the cortex.
In order to measure atrophy, previous studies were forced to rely upon voxel-based morphometry, which uses high-resolution images to compare regions of gray matter between different subjects´ brains. This method, however, is only able to provide an estimate of the brain´s overall cortical volume.
The Italian team, however, tackled the issue in a new and inventive way, utilizing a surface-based MRI method that enabled them to more accurately measure cortical thickness.
"For the first time, we assessed cortical thickness and surface area abnormalities in patients with migraine, which are two components of cortical volume that provide different and complementary pieces of information," said Massimo Filippi, MD, director of the Neuroimaging Research Unit at the University Ospedale San Raffaele and professor of neurology at the University Vita-Salute's San Raffaele Scientific Institute in Milan.
"Indeed, cortical surface area increases dramatically during late fetal development as a consequence of cortical folding, while cortical thickness changes dynamically throughout the entire life span as a consequence of development and disease."
Filippi and his team observed a total of 63 diagnosed migraine patients and 18 non-migraine sufferers for their study, in which they used MRIs to obtain a T2-weighted and 3-D T1-weighted brain images. Once that data was collected, the team used special software together with statistical analyses to estimate their study subjects´ cortical thickness and surface area. With this information in hand, the researchers then correlated it with the patients´ clinical and radiologic characteristics.
When compared to the control participants, the team noted the subjects who had been diagnosed as migraine sufferers presented a significantly reduced cortical thickness and overall surface area in regions of the cortex specifically related to the processing of pain. As the researchers pointed out, the anatomical overlap of cortical thickness and cortical surface area abnormalities was minimal. The cortical surface area abnormalities were far more pronounced than cortical thickness abnormalities alone.
The team also noticed the presence of aura and white matter hyperintensities, which themselves are areas of high intensity on an MRI. These also appeared to be more common in individuals who suffer from migraines. The team believes that this is related to the regional distribution of cortical thickness and surface area abnormalities, and may actually have no bearing on disease duration and frequency of migraine attacks.
"The most important finding of our study was that cortical abnormalities that occur in patients with migraine are a result of the balance between an intrinsic predisposition, as suggested by cortical surface area modification, and disease-related processes, as indicated by cortical thickness abnormalities," Filippi said. "Accurate measurements of cortical abnormalities could help characterize migraine patients better and improve understanding of the pathophysiological processes underlying the condition."
Filippi believes his team´s work offers a launching point to eventually gain a fuller understanding of the meaning of cortical abnormalities in the pain processing areas of migraine patients.
"Whether the abnormalities are a consequence of the repetition of migraine attacks or represent an anatomical signature that predisposes to the development of the disease is still debated," he said. "In my opinion, they might contribute to make migraine patients more susceptible to pain and to an abnormal processing of painful conditions and stimuli."
From this point forward, Filippi and his team intend to further their study longitudinally, specifically focusing on the migraine patient group. Over time, they hope to observe the cortical abnormalities noted in this study and determine whether they remain stable or slowly degenerate over time.
The team is also examining the effects of treatments on the observed modifications of cortical folding and identifying pediatric patients who suffer from migraines in the hopes that they might be able assess whether the abnormalities correspond to a specific biomarker for the disease.