White matter changes in chronic and episodic migraine: a diffusion tensor imaging study.
BACKGROUND
White matter alterations have been observed in patients with migraine. However, no microstructural white matter alterations have been found particularly in episodic or chronic migraine patients, and there is limited research focused on the comparison between these two groups of migraine patients.


METHODS
Fifty-one healthy controls, 55 episodic migraine patients and 57 chronic migraine patients were recruited and underwent brain T1-weighted and diffusion-weighted MRI acquisition. Using Tract-Based Spatial Statistics (TBSS), fractional anisotropy, mean diffusivity, radial diffusivity and axial diffusivity were compared between the different groups. On the one hand, all migraine patients were compared against healthy controls. On the other hand, patients from each migraine group were compared between them and also against healthy controls. Correlation analysis between clinical features (duration of migraine in years, time from onset of chronic migraine in months, where applicable, and headache and migraine frequency, where applicable) and Diffusion Tensor Imaging measures was performed.


RESULTS
Fifty healthy controls, 54 episodic migraine and 56 chronic migraine patients were finally included in the analysis. Significant decreased axial diffusivity (p < .05 false discovery rate and by number of contrasts corrected) was found in chronic migraine compared to episodic migraine in 38 white matter regions from the Johns Hopkins University ICBM-DTI-81 White-Matter Atlas. Significant positive correlation was found between time from onset of chronic migraine and mean fractional anisotropy in the bilateral external capsule, and negative correlation between time from onset of chronic migraine and mean radial diffusivity in the bilateral external capsule.


CONCLUSIONS
These findings suggest global white matter structural differences between episodic migraine and chronic migraine. Patients with chronic migraine could present axonal integrity impairment in the first months of chronic migraine with respect to episodic migraine patients. White matter changes after the onset of chronic migraine might reflect a set of maladaptive plastic changes.
['Planchuelo-Gómez|Álvaro|Á|', 'García-Azorín|David|D|', 'Guerrero|Ángel L|ÁL|http://orcid.org/0000-0001-7493-6002', 'Aja-Fernández|Santiago|S|', 'Rodríguez|Margarita|M|', 'de Luis-García|Rodrigo|R|']
D000328:Adult D016880:Anisotropy D016022:Case-Control Studies D002908:Chronic Disease D038524:Diffusion Magnetic Resonance Imaging D056324:Diffusion Tensor Imaging D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D008881:Migraine Disorders D066127:White Matter
Migraine Diffusion tensor imaging Chronic migraine Tract-based spatial statistics Magnetic resonance imaging (MRI)