The Relation Between Injury of the Spinothalamocortical Tract and Central Pain in Chronic Patients With Mild Traumatic Brain Injury.

Objectives: Little is known about the pathogenetic etiology of central pain in patients with traumatic brain injury (TBI). We investigated the relation between injury of the spinothalamocortical tract (STT) and chronic central pain in patients with mild TBI.

Design: Retrospective survey.

Participants: We recruited 40 consecutive chronic patients with mild TBI and 21 normal control subjects: 8 patients were excluded by the inclusion criteria and the remaining 32 patients were finally recruited. The patients were classified according to 2 groups based on the presence of central pain: the pain group (22 patients) and the nonpain group (10 patients).

Methods: Diffusion tensor tractography for the STT was performed using the Functional Magnetic Resonance Imaging of the Brain Software Library. Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume of each STT were measured.

Results: Lower FA value and tract volume were observed in the pain group than in the nonpain group and the control group (P < .05). By contrast, higher MD value was observed in the pain group than in the nonpain group and the control group (P < .05). However, no significant differences in all diffusion tensor imaging parameters were observed between the nonpain group and the control group (P > .05).

Conclusions: Decreased FA and tract volume and increased MD of the STTs in the pain group appeared to indicate injury of the STT. As a result, we found that injury of the STT is related to the occurrence of central pain in patients with mild TBI. We believe that injury of the STT is a pathogenetic etiology of central pain following mild TBI.