Diffusion abnormalities in the primary sensorimotor pathways in writer's cramp.

OBJECTIVE To determine whether there are diffusion abnormalities along the fibers connecting sensorimotor regions, including the primary sensorimotor areas and the striatum, in patients with writer's cramp using voxel-based diffusion analysis and fiber tracking. Recent studies have shown structural changes in these regions in writer's cramp. DESIGN Patient and control group comparison. SETTING Referral center for movement disorders. PARTICIPANTS Twenty-six right-handed patients with writer's cramp and 26 right-handed healthy control subjects matched for sex and age. INTERVENTIONS Clinical motor evaluations. MAIN OUTCOME MEASURES Fractional anisotropy changes and results of fiber tracking in writer's cramp. RESULTS Diffusion-tensor imaging revealed increased fractional anisotropy bilaterally in the white matter of the posterior limb of the internal capsule and adjacent structures in the patients with writer's cramp. Fiber tracking demonstrated that fractional anisotropy changes involve fiber tracts connecting the primary sensorimotor areas with subcortical structures. CONCLUSIONS Diffusion abnormalities are present in fiber tracts connecting the primary sensorimotor areas with subcortical structures in writer's cramp. These abnormalities strengthen the role of the corticosubcortical pathways in the pathophysiologic mechanisms of writer's cramp.