Compared with healthy controls, patients with migraine attacks showed cortical thinning in specific regions of the brain involved in pain processing, according to results published in Cephalalgia. In addition, factors of disease duration and frequency of migraine attacks were predictors of these cortical abnormalities.
Previous studies on cortical abnormalities have reported inconsistent findings. The investigators of this large cohort study sought to examine the relationship between changes in cortical thickness and clinical factors (including frequency of migraine, disease duration, headache lateralization, and demographic factors like age-related thinning) in patients with episodic migraine.
The study included adults from 4 academic headache centers across Europe and the United States, including 131 patients with migraine (38 with aura, 93 without aura) and 115 healthy controls. The investigators acquired MRI data on 3 Tesla systems; all 4 centers used different MRI systems and vendors. Differences in cortical thickness were estimated by FreeSurfer and quality of tissue segmentation was assessed by an experienced user.
The association between clinical factors and cortical thickness was compared between groups using a vertex-wise linear model and was controlled for variables, such as age, gender, and MRI scanner. An exploratory analysis was also performed to compare migraine patients experiencing aura with migraine patients without aura and both subgroups with controls.
Compared with the control group, participants with migraine had areas of significantly thinner cortex bilaterally in the central sulcus, the left middle-frontal gyrus, left primary and secondary visual cortices, and in the right occipital-temporal gyrus. Adjusting for age, gender, and MRI scanner, analysis showed clinical factors — specifically frequency of migraine and disease duration — had a significant effect on the cortical thickness of the left middle frontal gyrus and the left central sulcus.
In patients without aura, the investigators observed consistent cortical thinning with the whole sample with additional clusters of thinned cortex in the left supramarginal gyrus and in the right cuneus. Patients with aura showed a different pattern of cortical thickness in which thinning was observed bilaterally in the subparietal sulcus, the left intraparietal sulcus, and in the right anterior cingulate cortex.
The investigators indicated all of these brain regions are involved in different aspects of pain processing, such as pain localization and intensity (somatosensory cortex), evaluation and modulation of pain (frontal lobe), and pain perception and anticipation (occipito-temporal gyrus).
Limitations to the study include the generalizability of the findings to a greater population of patients with migraine, particularly because previous studies mostly involved small sample sizes and published inconsistent results.
Cortical abnormalities in specific regions of the brain were associated with migraine; clinical factors including migraine frequency and disease duration predicted cortical thinning of the left middle frontal gyrus and left central sulcus. Although the underlying pathophysiological mechanisms remain unclear, the investigators suggest cortical thinning may be attributed to genetic susceptibility or the result of repetitive pain from migraine attacks.
Magon S, May A, Stankewitz A, et al. Cortical abnormalities in episodic migraine: a multi-center 3T MRI study [published online December 10, 2018]. Cephalalgia. doi: 10.1177/0333102418795163