Patients who suffer from migraines have reduced cortical thickness and surface area in pain-processing regions of the brain, compared to individuals who never have migraines, Italian researchers revealed.
They explained in the journal Radiology that brain abnormalities in migraine sufferers may be either present at birth, or develop over time.
Migraines are severe, throbbing headaches, which are sometimes accompanied by sensitivity to light, nausea and even vomiting. In some cases, the patient experiences a change in visual function (aura) before or during the headache period. According to WHO (World Health Organization), over 300 million people globally suffer from migraines.
Previous migraine studies found atrophy of cortical regions in the brain related to pain processing. It was suggested that the deterioration was due to chronic stimulation of those areas – if people have a lot of persistent pain, there will be much stimulation in the area.
Cortical regions refers to the cerebral cortex. The cerebral cortex, often referred to as simply “the cortex”, is a thin layer of gray matter that covers the surface of each hemisphere of the brain (cerebral hemisphere). The cortex is crumpled and folded, forming several crevices (sulci) and convolutions (gyri). The cortex is responsible for the processes of memory, perception, thought, pain, and serves as the seat of social abilities, language, problem solving and advanced motor function.
For the most part, previous research relied on voxel-based morphometry, which estimated the volume of the cortex. In this latest study, the scientists used a different approach – they measured cortical thickness with a surface-based MRI mehod.
Massimo Filippi, M.D., 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, both in Italy, said:
“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.
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.”
Dr. Filippi and team used MRI (magnetic resonance imaging) to obtain T2-weighted and 3-D T1-weighted brain images from 81 volunteers – 63 of them were chronic migraine suffers while the other 18 never suffered from migraines (healthy controls). Using a special software program and statistical analysis, they estimated each participant’s brain’s cortical thickness and surface area and correlated the measurements with their clinical and radiologic characteristics.
They found that:
- Those with migraines had thinner cortexes and smaller surface areas in regions related to pain-processing compared to the healthy controls
- Cortical surface area abnormalities were more pronounced and distributed than cortical thickness abnormalities among the participants with migraines
Dr. Filippi said:
“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.
Accurate measurements of cortical abnormalities could help characterize migraine patients better and improve understanding of the pathophysiological processes underlying the condition.”
Dr. Filippi said that further studies are required to understand the meaning of cortical abnormalities in the pain processing areas of migraine patients more fully.
Dr. Filippi added:
“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.”
The team are currently carrying out a longitudinal study of the same patient group to determine whether their cortical abnormalities are stable or tend to worsen over the course of the disease. They are also trying to establish whether the abnormalities observed might represent a biomarker for migraine.
In 2007, Dr Nouchine Hadjikhani, of The Martinos Center for Biomedical Imaging at Massachusetts General Hospital in Charlestown, Massachusetts, and colleagues wrote in the journal Neurology that the cortex area of the brain is thicker in people who have migraines, compared to those who do not have migraines.
Dr Hadjikhani said that they could not determine whether the difference in cortex thickness was the cause of the migraines or whether having chronic migraine eventually led to a change in brain structure.
Dr Hadjikhani said “Repeated migraine attacks may lead to, or be the result of, these structural changes in the brain. Most of these people had been suffering from migraines since childhood, so the long-term overstimulation of the sensory fields in the cortex could explain these changes.”
Written by Christian Nordqvist