Decomposition of postural movements in individuals with mild TBI while reaching to intercept a moving virtual target

The study analyzed postural and arm movement coordinations in patients with traumatic brain injury (TBI) while standing and reaching for a target moving in a 3D virtual environment. Thirteen individuals with mild TBI and 13 height, sex, and age-matched healthy control individuals were involved. While standing in front of the screen, the participants interacted with the projected environment by reaching for virtual targets. Coordination was analyzed as the percentage of reach-to-intercept cycle time during which their movement toward the target was decomposed with 0% indicating simultaneous motion in three planes or 100% indicating motion in one or two planes only. Decomposition was calculated for the postural movements (DI_p), arm movements (DI_a), and arm-postural coordination (DI_a-p). The latter index represented the percentage of reach-to-intercept cycle time during which either the posture or arm moved alone. DI_p and DI_a-p were larger in the TBI group compared to the control group (p < 0.01). In the TBI group, DI_p and DI_a-p correlated negatively with postural stability (r = - 0.71 and r = - 0.60; p < 0.01). Results suggest that individuals with TBI decompose postural and arm-postural coordinations during a reach-to-intercept task. This may be either a result of impaired postural control or an effort to compensate for instability. These abnormalities should be taken into consideration while planning physical therapy programs for individuals after brain injury.