MRI evaluation of myelopathic pain after spinal cord injury or spinal cord tumor surgery

Patients with spinal cord injury suffered from not only motor paralysis but also intolerable neuropathic pain. Regarding the mechanism, various theories such as functional changes in the brain, disorders within the spinal dorsal horn and/or spinothalamic tract have been proposed. However, the feasible animal models with solid reproducibility has been insufficiently verified. We have established the mice fMRI system, reported the results of mice-fMRI after L5 nerve injury and resting state-fMRI imaging after thoracic cord transection injury in mice. Furthermore, in a clinical setting we evaluated the brain morphometry of the cases with spinal intramedullary tumor surgery by VBM, and found the gray matter volume of some brain regions was increased related with pain intensity. Besides fMRI and VBM analysis, we developed diffusion MRI techniques which could depict neuronal axons and myelination within the spinal cord ("diffusion tensor tractgraphy" and "myelin map", respectively). In this review, I would like to outline our results of MRI analysis of neuropathic pain so far.