A review of diffusion tensor imaging studies on motor recovery mechanisms in stroke patients.

For the past decade, diffusion tensor imaging (DTI) has been used in elucidation of the motor recovery mechanisms in stroke patients. In the current study, I reviewed the DTI studies with regard to the motor recovery mechanisms in stroke patients, according to the following classification of motor recovery mechanisms; recovery of a damaged lateral corticospinal tract (CST), subcortical peri-lesional reorganization, ipsilateral motor pathway from the unaffected motor cortex to the affected extremities, and other motor recovery mechanisms. In addition, I discussed the characteristics of DTI as an evaluation tool for motor recovery mechanisms and future direction. DTI has a unique advantage in identification and estimation of neural tracts at the subcortical level. Therefore, it could contribute much to research on the motor recovery mechanisms of stroke patients, especially, in terms of recovery of a damaged CST and subcortical peri-lesional reorganization. In spite of the advantages of DTI, fewer DTI studies on this topic have been conducted compared to studies using transcranial magnetic stimulation or functional MRI. Therefore, the total number of DTI studies on this topic should be increased. Moreover, further studies on various topics related to brain plasticity of motor function, as well as the motor recovery mechanism itself, should be encouraged; for example, DTI changes with passage of time, with rehabilitative intervention, or with motor recovery.