Interictal alterations of the trigeminal somatosensory pathway and periaqueductal gray matter in migraine.

Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
Neuroreport (Impact Factor: 1.64). 04/2007; 18(4):301-5. DOI: 10.1097/WNR.0b013e32801776bb
Source: PubMed

ABSTRACT Migraine has been traditionally considered a nonprogressive, paroxysmal disorder with no brain abnormalities between attacks. We used diffusion tensor imaging to examine interictal diffusion properties of the brains of migraineurs with aura, migraineurs without aura and matched healthy controls. Areas of lower fractional anisotropy were present in migraineurs along the thalamocortical tract. In addition, migraineurs with aura had lower fractional anisotropy in the ventral trigeminothalamic tract, and migraineurs without aura had lower fractional anisotropy in the ventrolateral periaqueductal grey matter. Our results indicate the presence of permanent interictal changes in migraineurs, pointing to an effect of migraine on the trigeminal somatosensory and modulatory pain systems.

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    ABSTRACT: Transcranial Direct Current Stimulation (tDCS) is a method of non-invasive brain stimulation that has been frequently used in experimental and clinical pain studies. However, the molecular mechanisms underlying tDCS-mediated pain control, and most important its placebo component, are not completely established. In this pilot study, we investigated in vivo the involvement of the endogenous μ-opioid system in the global tDCS-analgesia experience. Nine healthy volunteers went through positron emission tomography (PET) scans with [11C]carfentanil, a selective μ-opioid receptor (MOR) radiotracer, to measure the central MOR activity during tDCS in vivo (non-displaceable binding potential, BPND) - one of the main analgesic mechanisms in the brain. Placebo and real anodal primary motor cortex (M1/2mA) tDCS were delivered sequentially for 20 minutes each during the PET scan. The initial placebo tDCS phase induced a decrease in MOR BPND in the periaqueductal gray matter (PAG), precuneus, and thalamus, indicating activation of endogenous μ-opioid neurotransmission, even before the active tDCS. The subsequent real tDCS also induced MOR activation in the PAG and precuneus, which were positively correlated to the changes observed with placebo tDCS. Nonetheless, real tDCS had an additional MOR activation in the left prefrontal cortex. Although significant changes in the MOR BPND occurred with both placebo and real tDCS, significant analgesic effects, measured by improvements in the heat and cold pain thresholds, were only observed after real tDCS, not the placebo tDCS. This study gives preliminary evidence that the analgesic effects reported with M1-tDCS, can be in part related to the recruitment of the same endogenous MOR mechanisms induced by placebo, and that such effects can be purposely optimized by real tDCS.
    PLoS ONE 07/2014; 9(7):e102350. DOI:10.1371/journal.pone.0102350 · 3.53 Impact Factor
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    Frontiers in Cellular Neuroscience 10/2014; 8:302. DOI:10.3389/fncel.2014.00302 · 4.18 Impact Factor
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    ABSTRACT: Background In patients with episodic migraine (EM), diffusion tensor imaging (DTI) revealed microstructural white matter alterations in various brain regions related to pain processing. Some of these changes were correlated with migraine duration and attack frequency, suggesting that migraine is a progressive disease with proceeding structural alterations of the brain. This study aimed to identify possible microstructural white matter alterations in patients with chronic migraine (CM) using DTI. We hypothesized that alterations in DTI are more pronounced in patients with CM compared with EM.Methods Individually, age- and sex-matched subjects with CM without aura, EM without aura, and healthy controls (n = 21 per group) underwent conventional head magnetic resonance imaging and DTI imaging in a 3T MRI scanner and were included in analysis. DTI data were analyzed using a tract-based spatial statistics approach. Fractional anisotropy (FA), mean diffusivity, radial diffusivity, and axial diffusivity were compared between subjects with CM and EM, CM and controls, EM and controls, as well as between all subjects with migraine (EM + CM) and controls.ResultsIn chronic migraineurs (mean age 49 ± 7.5 years), we did not find any statistically significant difference (P < .05, threshold-free cluster enhancement corrected for multiple comparison) in DTI-derived parameters in comparison with episodic migraineurs (FA: P > .245) and healthy controls (FA: P > .099). In contrast to previous DTI studies, we did not find alterations in DTI-derived indices in subjects with EM compared with healthy controls (FA: P > .486).Conclusions No microstructural white matter changes could be observed in middle-aged chronic and episodic migraineurs using DTI. CM does not seem to be a risk factor for progressive microstructural changes in DTI.
    Headache The Journal of Head and Face Pain 02/2015; 55(2). DOI:10.1111/head.12496 · 3.19 Impact Factor

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