Abstract: Post-traumatic movement disorder is one of the sequelae of traumatic brain injury. The dentatorubrotha- lamic tract (DRTT) is reported to be involved in the control of movement. Therefore, injury of the DRTT can be accompanied by abnormal movements, including ataxia, tremor, or dystonia. We investigated DRTT injuries in 27 patients who showed post-traumatic tremor in at least one of four extremities following mild traumatic brain injury. We classified DRTT injuries based on diffusion tensor tractography parameters and configuration: type A: the DRTT showed narrowing, type B: the DRTT showed partial tearing, and type C: the DRTT showed discontinuation. Fractional anisotropy and fiber number of the DRTT were significantly decreased in patients compared with the healthy controls. Based on our DRTT injury classification, among the 54 hemispheres of the 27 patients, type A injury occurred in 22 hemispheres (40.7%) of 17 patients, type B injury was present in 15 hemispheres (27.7%) of 10 patients, and type C injury was observed in 8 hemi- spheres (14.8%) of 6 patients. Our results suggest that diffusion tensor tractography-based evaluation of the DRTT would be useful when determining cause of post-traumatic tremor in patients with mild traumatic brain injury. The study protocol was approved by the Institutional Review Board of Yeungnam University Hospital (YUMC-2018-09-007) on September 5, 2018.

Key words: dentatorubrothalamic tract, diffusion tensor imaging, diffusion tensor tractography, fiber number, fractional anisotropy, mild traumatic brain injury, post-traumatic tremor, region of interest