White Matter Microstructure Abnormalities in Paediatric Migraine Patients: In-Vivo Measures of Brain Hyperexcitability? (P6.201)

OBJECTIVE: To explore abnormalities of white matter (WM) microstructure in paediatric patients with migraine using diffusion tensor (DT) magnetic resonance imaging (MRI) and two different methods of analysis. BACKGROUND: By exploiting diffusion characteristics of water molecules in the central nervous system, DT MRI provides several quantities with the potential to disclose WM microstructure abnormalities. Among these, fractional anisotropy (FA) reflects axonal integrity and fiber organization, mean diffusivity (MD) measures the overall magnitude of diffusion, axial diffusivity (AD) is associated with fiber density and axon intrinsic characteristics, whereas radial diffusivity (RD) reflects the degree of myelination. DESIGN/METHODS: Using a 3.0 Tesla scanner, dual-echo and DT MRI scans were acquired from 15 paediatric migraine patients (8 girls, mean age=14.1 years, mean disease duration=3 years, mean attack frequency=21 attacks per year, 8 with visual aura and 7 without aura) and 15 age-matched controls. Tract-based spatial statistics (TBSS) analysis was performed using FMRIB's Diffusion Toolbox. In order to confirm TBSS results, we also performed a DT probabilistic tractography analysis. RESULTS: Both TBSS and DT tractography analysis showed that compared to controls, paediatric migraine patients had significant lower MD, AD and RD in the brainstem, thalamus, fronto-temporo-occipital lobes, including the right cingulum, corpus callosum, optic radiation, fronto-occipital fasciculus and corticospinal tract, bilaterally. They also experienced increased FA of the left optic radiation. No correlation was found between WM abnormalities and disease duration and frequency of attacks. CONCLUSIONS: Paediatric migraine patients present diffuse WM microstructural abnormalities. Higher FA and lower MD, AD and RD might be explained by repeated neuronal activation, that is likely to lead to cells swelling and might stimulate the activity-dependent myelo-modulation, or by the presence of higher neuronal and synaptic densities in migraine patients compared to controls. Both these mechanisms would reflect an hyperexcitability of the brain in migraine patients. Study Supported by: