Validation of reaching in a virtual environment in typically developing children and children with mild unilateral cerebral palsy.

AimTo compare three reaching movements made in two planes between a low-cost, game-based virtual reality and a matched physical environment in typically developing children and children with cerebral palsy (CP). To determine if differences in kinematics are related to sensory deficits. MethodAn observational study in which 27 children (typically developing, n=17, mean age 13y, [SD] 2y 2mo, range 9y 3mo-17y 2mo; CP, n=10, mean age 13y 8mo, [SD] 1y 8mo, range 11y 1mo-17y 1mo, Manual Ability Classification System levels I-II) performed 15 trials of threegestures in each of a virtual reality and a matched physical environment. Upper-limb and trunk kinematics were recorded using an electromagnetic system (G4, Polhemus, six markers, 120Hz). ResultsCompared to the physical environment, movements in virtual reality made by typically developing children were slower (p=0.002), and involved less trunk flexion (p=0.002) and rotation (p=0.026). Children with CP had more curved trajectories (p=0.005) and used less trunk flexion (p=0.003) and rotation (p=0.005). Elbow and shoulder kinematics differed from 2.8% to 155.4% between environments in both groups. Between groups, there were small, clinically insignificant differences with only the vertical gesture being longer in typically developing children. Children with CP who had greater tactile impairment used more trunk displacement. InterpretationClinicians and researchers need to be aware of differences in movement variables when setting goals or designing protocols for improving reaching in children with CP using low-cost, game-based virtual reality systems.