Recent Developments in Neuroimaging for the Evaluation of
Migraines
Yasushi
Shibata
Yasushi Shibata, Department of Neurosurgery, Headache
Clinic, Mito Medical Center, University of Tsukuba, Tsukuba, Mito Kyodo General
Hospital, Miyamachi 3-2-7, Mito, Ibraki, 3100015, Japan
Correspondence to: Yasushi Shibata, MD, PhD, Department of
Neurosurgery, Headache Clinic, Mito Medical Center, University of Tsukuba,
Tsukuba, Mito Kyodo General Hospital, Miyamachi 3-2-7, Mito, Ibraki, 3100015,
Japan
Email: yshibata@md.tsukuba.ac.jp
Telephone: + 81-29231-2371
Received: March 28,
2015
Revised: May 10, 2015
Accepted: May 13, 2015
Published online: June 2, 2015
ABSTRACT
Although migraines
are a common disease, the pathophysiology of migraines is not completely
understood. A clinical diagnosis of a migraine is currently made based only on
the symptoms, because a clinically useful biomarker or laboratory test for the
diagnosis of migraines has not been established. The recent advances in
neuroimaging have improved the understanding of the pathophysiology of
migraines. These neuroimaging studies may provide useful biomarkers for the
diagnosis and monitoring of migraines. Anatomical magnetic resonance imaging
(MRI) of the brain is mainly used to rule out secondary headaches. However, a
statistical analysis of the MRI findings revealed volume loss of some brain
regions. Diffusion tensor imaging (DTI) revealed faint functional changes of
white matter fibers. Recently tract-based statistical analysis (TBSS) has
provided an objective statistical analysis of the DTI findings for each
patient. TBSS revealed reduced fractional anisotropy in some brain regions,
like the corpus callosum. These brain regions are associated with pain
processing, so these anatomical and functional alterations may cause
chronification of migraines. These imaging findings may be diagnostic for
migraines and effective to predict the prognosis and select therapeutic
interventions and medications that will provide the best outcome.
© 2015 ACT. All
rights reserved.
Key words: Migraine; Cortical thickness; MRI; Diffusion tensor
imaging; Neuroimaging, Volumetory
Shibata Y. Recent
Developments in Neuroimaging for the Evaluation of Migraines. International
Journal of Radiology 2015; 2(1): 15-16 Available from: URL:
http://www.ghrnet.org/index.php/ijr/article/view/1135
EDITORIAL
Although migraines are a common disease, the
pathophysiology of migraines is not completely understood. A clinical diagnosis
of a migraine is currently made based only on the symptoms, because a
clinically useful biomarker or laboratory test for the diagnosis of migraines
has not been established. The recent advances in neuroimaging have improved the
understanding of the pathophysiology of migraines. These neuroimaging studies
may provide useful biomarkers for the diagnosis and monitoring of migraines.
Although cerebral infarctions were frequently accompanied with migraine,
the pathological relationship between the two conditions is not clearly
understood. Anatomical magnetic resonance imaging (MRI) of the brain is mainly
used to rule out secondary headaches. However, a statistical analysis of the
MRI findings revealed volume change of some brain regions. Functional and
metabolic reductions have also been observed in these regions.
Chong et al reported the presence of cortical thinning at the
bilateral postcentral gyrus in cases presenting with episodic migraine and
compared these patients with healthy controls[1]. These 27 migraine
patients were mostly female, and the mean age was 33.6 years. They did not
analyze cortical thickness in relation to either the disease duration or
headache frequency. Kim et al. reported cortical thickening to be present in
the bilateral postcentral gyrus in migraine patients without aura and compared
their findings with control subjects[2]. This thickening was related
to both the disease duration and headache frequency. They excluded male
patients because of a sex difference in regard to cortical thickness. The final
study population comprised 56 female migraine patients, with a mean age of 35.7
years. These 2 studies had almost the same patient background and both used the
3T MR device, the same software and the same analysis methods. However, the
results were completely contradictory. DaSilva et al. reported that migraineurs
had a thicker somatosensory cortex than age and sex matched controls[3].
They discussed that individuals suffering from acquired pain disorder may thus
develop thinning of the cortex, while the long-term overstimulation of the
sensory cortex may cause thickening of the sensory cortex. Maleki et al
analyzed sensory cortical thickness for migraineurs[4]. In high
attack frequent migraineurs, the degree of sensory cortical thickness was
higher than in healthy control, however, in low attack frequency migraineurs,
the cortical thickness was lower than that in healthy control. They concluded
that cortical thinning is the result of initial damage and as the frequency of
migraine increases, and increased demand of sensory processing may thus be
compensated by adaptive cortical thickening. The mean age of migraine patients
was more than 40, and mostly female. They did not analyze the disease duration.
Large amounts of medication were administered to high attack frequency
migraineurs. Messina et al analyzed both cortical thickness and the
cortical surface area in patients with migraine[5]. They
demonstrated a reduced cortical thickness and surface area in the regions
subserving pain processing and an increased cortical thickness and surface area
in the regions involved in the executive functions and visual motion
processing. These cortical thickness and surface area abnormalities were not
related with the migraine disease duration and attack frequency. The cortical
surface area increases during fetal development, while cortical thickness
changes during the life span. In migraine patients, cortical surface area
abnormalities were more frequently observed than cortical thickness changes,
thus suggesting that congenital abnormalities therefore exist more frequently
that acquired changes in migraine. Cortical thickness is according to age and
sex. As a result, the cortical thickness should be analyzed among same age and
sex groups in relation with the disease duration and attack frequency. In
addition, therapeutic intervention may affect cortical thickness. Therefore,
before discussing whether or not changes in cortical thickness may be the cause
or result of migraine, we should first investigate the natural course of
cortical change in patients with migraine.
Diffusion tensor imaging (DTI) revealed faint functional changes of
white matter fibers. Recently tract-based statistical analysis (TBSS) has
provided an objective statistical analysis of the DTI findings for each
patient. TBSS revealed reduced fractional anisotropy (FA) in some brain
regions, like the corpus callosum. These brain regions are associated with pain
processing, so these anatomical and functional alterations may cause
chronification of migraines.
Schmitz et al showed a significantly reduced FA in the superior,
medial frontal lobe in patients with migraine, and a longer disease duration in
patients demonstrating a reduced frontal FA. They included only female migraine
patients and the age-FA correlation was not analyzed[6]. Szabo et
al analyzed DTI using TBSS and found a reduced FA in right frontal white
matter clusters in migraine[7]. The attack frequency or migraine
duration was not associated with FA change. They discussed that structural
changes could be the consequence of maladaptive plastic changes or some
degenerative process caused by the migraine pathology. Yuan et al. demonstrated
a reduced FA in genu and splenium of corpus callosum in migraine patients and
these changes correlated with the disease duration[8]. FA is known
to be related with age, so FA should be evaluated using age-matched controls.
If these changes are the result of repeated migraine attacks, they
likely correlate with the duration and frequency of the migraine. However, if
these changes are observed in young patients with recently started migraines,
these changes may indicate a predisposition for or cause of migraines. The
effects of therapeutic intervention on the functional changes of MRI findings
should be investigated. These imaging findings may be diagnostic for migraines
and effective to predict the prognosis and select therapeutic interventions and
medications that will provide the best outcome.
The
cortical thickness and FA are related with the duration and frequency of
migraine in some studies, but not in other studies. These unstable results
indicated the change of cortical thickness and FA are not simple results of the
pathology of migraine. Therefore, further regression analyses using homogenous
patients groups and longitudinal studies should be carried out to elucidate the
pathophysiology of migraine.
CONFLICT OF INTERESTS
There are no
conflicts of interest with regard to the present study.
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Peer reviewers: Ayşe Aralaşmak, MD,
Associate Prof of Radiology, Bezmialem Vakif University, Department of
Radiology, Division of Neuroradiology, Fatih/Istanbul, 34093, Turkey.
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