Brain-behavior relationships in young traumatic brain injury patients: DTI metrics are highly correlated with postural control

Abstract

Traumatic brain injury (TBI) is a major cause of impairment and functional disability in children and adolescents, including deterioration in fine as well as gross motor skills. The aim of this study was to assess deficits in sensory organization and postural ability in a young group of TBI patients versus controls by using quantitative force-platform recordings, and to test whether balance deficits are related to variation in structural properties of the motor and sensory white matter pathways. Twelve patients with TBI and 14 controls (aged 8-20 years) performed the Sensory Organisation Test (SOT) protocol of the EquiTest (Neurocom). All participants were scanned using Diffusion Tensor Imaging (DTI) along with standard anatomical scans. Quantitative comparisons of DTI parameters (fractional anisotropy, axial and radial diffusivity) between TBI patients and controls were performed. Correlations between DTI parameters and SOT balance scores were determined. Findings revealed that the TBI group scored generally lower than the control group on the SOT, indicative of deficits in postural control. In the TBI group, reductions in fractional anisotropy were noted in the cerebellum, posterior thalamic radiation, and corticospinal tract. Degree of white matter deterioration was highly correlated with balance deficits. This study supports the view that DTI is a valuable tool for assessing the integrity of white matter structures and for selectively predicting functional motor deficits in TBI patients.

Figure 1

Schematic representation of the six conditions of the Sensory Organisation Test of the EquiTest System. Reproduced with permission from NeuroCom International, Clackamas, Oregon. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 2

Sensory and motor tracts used in the study. Tracts were reconstructed and displayed on a 3D T1‐image for a typical control subject: Corticospinal tract (cyan), inferior cerebellar peduncle (red), middle cerebellar peduncle (yellow), medial lemniscus (magenta), posterior thalamic radiation (orange), and superior cerebellar peduncle (green). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 3

Example sensory and motor regions of interest masks depicted on fractional anisotropy maps of the white‐matter atlas of Mori et al. (2005): Anterior limb of the internal capsule (red), posterior limb of the internal capsule (yellow), cerebellum (green), brainstem (blue), pons (violet), cerebral peduncle (orange). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 4

Graph depicting the significant interaction effect between sensory condition and group. The TBI group performed significantly worse than the controls on condition 5 (eyes closed, sway referenced surface). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

Figure 5

Scatter plot indicating the relationship between FA and equilibrium scores of the SOT within the TBI group.