Are these changes part of the cause of Migraine attacks, or are they the result of repetitive Migraine attacks?
A study published in the November 20, 2007, issue of Neurology®, the medical journal of the American Academy of Neurology, indicates that people with Migraines have differences in part of the cortex, an area of the brain that helps process sensory information, including pain. The study found that part of the cortex area of the brain is thicker in people with Migraine than in people who do not have the neurological disease.
"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. It's also possible that people who develop Migraines are naturally more sensitive to stimulation...
This may explain why people with Migraines often also have other pain disorders such as back pain, jaw pain, and other sensory problems such as allodynia, where the skin becomes so sensitive that even a gentle breeze can be painful."
study author Nouchine Hadjikhani, MD Martinos Center for Biomedical Imaging at Massachusetts General Hospital in Boston
Background: Migraine disease, for some Migraineurs, means only occasional and easily treated Migraine attacks. For others, Migraine is a life-long chronic disease, and Migraine attacks have a quit significant impact on their lives. Questions abound about whether Migraine attacks cause serious and /or permanent changes in the brain.
This study is difficult to explain without using some medical terminology about the brain and its functions. Please see the bottom of the article for some definitions.******
The thickness of the cerebral cortex varies with the SSC being one of the thinnest regions in the brain. Recent studies have shown decreases in thickness decreases in patients with neurological diseases such as multiple sclerosis and Alzheimer's disease. Another study by the same researchers as this study reported changes in the visual cortex of Migraineurs. A question this raises is whether the changes are the result or cause of mechanisms in the central nervous system. Understanding these changes may hold a key to better understanding Migraine and other neurological diseases, and by extension, the development of better treatments.
Study objective: To examine structural changes in the somatosensory cortex (SSC) of Migraineurs.
- The study cohort (a group of individuals with some characteristics in common) was comprised of 24 patient with Migraine disease and 12 control patients with out Migraine.
- The cohort of Migraineurs was comprised of 12 patients diagnosed with Migraine without aura (MWA) and 12 diagnosed with Migraine without aura (MWOA).
- Cortical thickness of the SSC of patients with migraine was measured and compared with age- and sex-matched control subjects.
- Migraineurs had on average thicker SSCs than the control group.
- The most significant thickness changes were noticed in the caudal SSC, where the trigeminal area, including head and face, is represented.
- MWOA study participants showed clusters of thickening in more areas of the SSC than MWA participants.
"In conclusion, the current findings of gray matter thickening of the SSC in addition to the previous discovery of white matter diffusional changes in the trigeminal somatosensory pathway of the same migraine cohort indicate that somatosensory mechanisms are important components in the migraine pathophysiology. These cortical and subcortical changes may be either the result or cause of repetitive migraine attacks, which may also affect other systems. This may explain the high comorbidity of migraine with other pain disorders, including back pain, temporomandibular disorders, and fibromyalgia besides sensory disturbances such as allodynia."1
Summary -- what does all of this mean to Migraineurs?
Dr. Richard B. Lipton, of the Montefiore Headache Clinic in New York, made some interesting comments that make a great deal of sense:
"The authors suggested that it may be that repeated attacks of migraine lead to the changes in the brain, although another possibility is that these alterations in the brain structure predispose to migraine... I have a bias in favor of the hypothesis they present -- that recurrent migraines alter the brain --- because I want to believe that if patients get treated with preventive medication and acute treatments, maybe this thickening could be prevented."5
It is clear that the part of the cerebral cortex responsible processing sensory signals including pain, the somatosensory cortex, has clusters of thickened areas in Migraineurs. What is not yet clear is the implications of these thickened areas.
The findings of this may help explain the high comorbidity of migraine with other pain disorders, including back pain, temporomandibular disorders, and fibromyalgia besides sensory disturbances such as allodynia. (Comorbidity refers to conditions that occur in a patient at the same time, but do not cause each other.)
Studies such as this one may well provide the basis to better understanding how a Migraine affects the brain. Studies, including this one, are now showing permanent changes to the brains of Migraineurs. Another question is -- Are these changes part of the cause of Migraine attacks, or are they the result of repetitive Migraine attacks?
- Cerebral cortex - the surface grey matter layer of the brain. A function of the cortex is to coordinate sensory and motor (movement) information.
- Somatosensory cortex (SSC) - Areas of the cerebral cortex, namely the primary somatosensory cortex, the secondary somatosensory area, and the somatosensory association area, devoted to processing information from the somatic receptors.3
- Somatosensory - sensory activity having its origin elsewhere than in the special sense organs (as eyes and ears) and conveying information about the state of the body proper and its immediate environment.4
1 Alexandre F.M. DaSilva, DDS, DMSc; Cristina Granziera, MD, PhD; Josh Snyder; Nouchine Hadjikhani, MD. "Thickening in the somatosensory cortex of patients with Migraine." Neurology® 2007;69:1990-1995.
2 Press Release: "Brain Differences Found in People with Migraine." St. Paul. American Academy of Neurology. November 19, 2007.
5 Gardner, Amanda. "Migraine Tied to Thickening in Brain Area." HealthDay News. November 19, 2007.