Migraine Linked to Structural Brain Changes
Caroline Cassels


November 19, 2007 — New research suggests repetitive migraine attacks may lead to or be the result of structural changes in the somatosensory cortex (SSC), offering a potential explanation for the high comorbidity of other pain disorders observed in migraineurs.

In a comparative study of individuals with migraine vs healthy controls, investigators at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital, in Boston, found, on average, migraineurs' SSCs were 21% thicker than those of nonmigraineurs.
The study is published in the November 20 issue of Neurology.
The most significant thickness changes were noted in the caudal SSC, where the trigeminal area, including head and face, is somatotopically represented, the investigators report.

"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," study investigator Nouchine Hadjikhani, MD, said in a statement from the American Academy of Neurology.

Dr. Hadjikhani added that changes in the SSC, which plays a crucial role in noxious and nonnoxious somatosensory processing, might explain why individuals with migraine frequently have other pain disorders, including back pain, temporomandibular disorders, and fibromyalgia as well as sensory disturbances such as allodynia.
Long-Term Sufferers
For the study investigators compared 24 individuals — 12 who had migraine with aura and 12 who had migraine without aura — with 12 age- and sex-matched controls.

Study subjects were assessed with magnetic resonance imaging (MRI). Patients ranged in age from 21 to 52 years. On average, those with migraine had experienced episodic attacks for the past 20 years, with age of onset occurring in most individuals during adolescence.

According to the study, the average pain intensity of the attacks was rated 6 out of 10 on the numeric analog scale, with a frequency of approximately 4 migraine attacks per month. None of the patients had a previous history of either other trigeminal chronic pain or current acute pain or any other major health disorder.

No Correlation to Clinical Data
Investigators also examined cortical thickness and correlated these findings with clinical data including migraine duration, age at onset, frequency, and disease time span.

On average, migraineurs had thicker SSCs than the control group. However, investigators found no clear correlation between cortical thickness changes and clinical data.
According to the authors, the thickening of the SSC is in line with a recent study of the same cohort, which showed diffusional abnormalities in the subcortical trigeminal somatosensory pathway.

"Repetitive migraine attacks may lead to or be the result of neuroplastic changes in cortical and subcortical structures of the trigeminal somatosensory system," they conclude.
The study was supported by the National Institutes of Health, the Swiss Heart Foundation, and the Harvard School of Dental Medicine Dean's Award. The authors report no conflicts of interest related to the study.
Neurology. 2007;69:1990-1995.

Hmm, I knew it wasn't really all just in my head. No, wait, I guess it really is; and now it's growing. And changing. Scary, isn't it.